Post-hoc tests after Kruskal-Wallis: Dunn's test or Bonferroni corrected Mann-Whitney tests?

I have some non-Gaussian distributed variable and I need to check if there are significant differences between the values of this variable in 5 different groups.  I have performed Kruskal-Wallis one-way analysis of variance (which came up significant) and after that I had to check which groups were significantly different. Since the groups are kind of sorted (the values of the variable in the first group are supposed to be lower than the values of the variable in the second group which are supposed to be lower than the values of the variable in the third group and so on) I only performed 4 tests:  Group 1 vs Group 2 Group 2 vs Group 3 Group 3 vs Group 4 Group 4 vs Group 5   I have performed this analysis with two different methods. I started by using Dunn's Multiple Comparison Test but nothing came up significant. On the other hand if I use Mann-Whitney test and correct for the number of tests (4) using Bonferroni, 3 tests come up significant.  What does it mean? Which results should I trust?


finding equivalence classes of $D^n/S^{n-1}$ and this hoemomorphism with $S^n$

Collapsing the unit sphere of the unit ball $S^{n-1} \subset D^n \subset \mathbb{R}^n$ to a point. How can I show that it ($D^n/S^{n-1}$) is homeomorphic to the sphere of one dimension higher ($S^n$)?  I thought about $D_n$ = {($x_1$, ..., $x_n$): $x_1$+$x_n$$\leqslant 1$} and $S_{n-1} = ${($x_1$, ..., $x_n$): $x_1$+...+$x_n$ = $1$}. So $D_n / S_{n-1}$ = $\bigcup_{z \in \left[-1, 1\right]}$ {($x_1$, ..., $x_n$, z): ${x_1}^2 + ... + {x_n}^2 = 1 - z^2$} = $\bigcup_{z \in \left[-1, 1\right]}$ {($x_1$, ..., $x_n$, z): ${x_1}^2 + ... + {x_n}^2 + z^2 = 1$}. And it is clearly similar to $S_{n}$. Can we use my idea to construct this homeomorphism sending ($x_1$, ..., $x_n$) in ($x_1$, ..., $x_n$, $z$)?


Bash - Separate files into different arrays based on filename

I have a folder of audio files. Most are single sounds -- or soundSprites -- while some are several soundSprites concatenated into spriteLists. These spriteLists use a naming convention with a _SL added to the end of the file name. How can I create two arrays of soundSprites and spriteLists? I've tried using find to exclude the spriteLists like so:  soundSprites+=($(find . -maxdepth 1 ! -name "*_SL*"))   But this adds a ./ before every file name which I want to avoid. Instead of figuring out how to then iterate through the array and remove every ./ I can only assume there's an elegant solution to this that I'm simply unaware of.  Any help is greatly appreciated.


"Class type" of "type parameter" used by generic java function

I have written the following generic function in Java:  public <T extends MyClass> void loadProperties(String in_strPath) {    // ... }   The type T can be any of 3 different classes which are children of MyClass. Let's call those 3 classes MyClassV1, MyClassV2 and MyClassV3. I would like to print the name of the class that corresponds to T from whithin loadProperties. I tried doing this:  Class<T> c = T.class; T instance = c.newInstace(); System.out.println(instance.getClass().getName());   But it does not work. Thanks for any advice.


Extract one number from another number in PHP

so tonight i was trying to create a function that will check if a credit card is valid or not. However i'm stuck here. In my calcul, i get number such as 10, 56, 30... number with 2 numbers.   (I mean, 1 is a number with 1 number just like 2, 3, 4 ,5 6, 7 , 8 ,9.. number with two numbers would be 10 ans higher.)  What I need to do is :   Get the first number and add it to a new variable, and do the same thing with another variable.   Example:  I have this number -> 23  I need to :  $var1 = 2;  $var2 = 3;  I wanted to use the function subtr, but it looks like it doesn't works with numbers ..  Thanks for reading !!


How to make regedit dark in windows 10 ? regedit window is not dark in dark mode  I searched about it but only find answers for How to enable dark  mode in windows 10 using  regedit?


I could join Software Recommendations during private beta without committing

I took a look at the  proposal on Area 51. There was a big link saying "visit the site now!" and out of curiosity I clicked it. To my surprise, I got the regular sign-up screen from Stack Exchange. So, I entered my credentials, expecting to see a warning that only committed users could do this. Instead, I could just join the site, despite never having committed to it, and despite the fact that the site is still in private beta.    I'm guessing this is a bug?


Adding 2D versions of real cars in a game can be a legal issue?

I've been thinking in doing a car game, but i wanted to add "real" cars into the game. Are 2D renditions of the cars with sprites/vector 2d graphics fine?


What happens if I try to redeem an old WoW expansion code?

If I have an old WoW expansion box lying around, what happens when I redeem it on Battle.Net?  (This is not a duplicate question, the other similar question does not have an adequate answer)


How to view who is connected to my Wi-Fi hotspot

I'm using stock android 9.0. I'd like to be able to get a list of the devices (IP and/or MAC) that are connected to my phone when it's used as a Wi-Fi AP.   Here are a few ways I tried but didn't work:   In the settings, there is an indicator of how many devices are connected (Network & internet / Hotspot & tethering / under Wi-Fi hotspot), but there is no list of them.  Fing only works when my phone is a client on a Wi-Fi network, not when it is an AP. On Oreo, the  /proc/net/arp file used to contain the list, but as of Pie, it doesn't (it's empty, even when something is connected).   I'm looking for a solution that does not require root.


What can I do to show my app on google results?

I uploaded my website to the server 2 days ago. I'm already being indexed by google and bing. I have a sitemap that they can read as it's confirmed in my g-analytic report and webmaster tools. Robots are find. I set the title, description, keywords. However, the website is not showing up on google results with keywords contained in my website title, description and so on. Is that the normal behavior considering that my web has been published just for 48 hours or less?  I must say I have strong competitors because is a website about puzzles and crosswords. Yet I feel I'm not doing things well. I'm open to any suggestion. I know it's too sun to get frustrated but still...


Canadian visa rules for flight connections

I know that in the US foreigners must have a US visa if they have a connection in the US, even if they fly from a different country to a different country. That is because in the US you have to go through passport control regardless of your final destination.  What is the situation in Canada? Does a person who would need a visa to enter Canada need a visa to connect through Canada without exiting the airport?


How to detect leading numberings in titles with a regex

I am trying to detect if a sequence of text begins with a numbering, eg I), IV., a), C/, C. C -, C- etc with a regex.  I tried the following regex :   m = re.search(r'^(IX?{\s|-|-\s|,|,\s|\)|\)\s|.|.\s}|IV?{\s|-\s|-|\)|\)\s|.\s|.}|VI{0,3}?{\s|-|-\s|\)|\)\s|.|.\s})', "II - Informations supplementaires") m.group(0) >> 'I' m.group(1) >> 'I'   It only gives me 'I' as a result, I don't have "II", "II -", which are expected .... What is my error in the pattern ^^ ?


Prove $(-a+b+c)(a-b+c)(a+b-c) \leq abc$, where $a, b$ and $c$ are positive real numbers

I have tried the arithmetic-geometric inequality on $(-a+b+c)(a-b+c)(a+b-c)$ which gives   $$(-a+b+c)(a-b+c)(a+b-c) \leq \left(\frac{a+b+c}{3}\right)^3$$   and on $abc$ which gives   $$abc \leq \left(\frac{a+b+c}{3}\right)^3.$$   Since both inequalities have the same righthand side, I have tried to deduce something about the lefthand sides, but to no avail. Can somebody help me, please? I am sure it is something simple I have missed.


Where do I set the Caps Lock key behaviour?

I have notice that since a few days my cap lock stays on if I press on caps lock. I can't desactivate it. I am currently using Ubuntu 12.04LTS on my old Emachines computer. So I would like to know where is the command to get back the default settings when I press the caps lock.


I learned that which and that are interchangeable; and I also learned that *which8 can be converted to and it.   Then how about these sentences?        In this chapter we presented a new context sharing scheme within    a pervasive and ad-hoc network that can address the problem in   many-to-many communication: a large number of context exchanges.   In this chapter we presented a new context sharing scheme within a pervasive and ad-hoc network which can address the problem in   many-to-many communication: a large number of context exchanges.   In this chapter we presented a new context sharing scheme within a pervasive and ad-hoc network, which can address the problem in   many-to-many communication: a large number of context exchanges.       Do 1 and 2 convey the exactly same meaning? How about 3? I think 3 is the correct statement, as what addresses the problem is "scheme" not "network" so there should be a *which" to explicitly show that.


Proof of friends relationship for a Canadian visitor visa

I’m applying for a visitor visa to see a friend.  I have my letter of invitation.  But at the questioner ask me about proof of relationship what can I submit?    After you reply you will be visiting any friends and you said you have an invitation letter at the final ask you to upload any proof of relation with the person such as marriage certificate , or common law or birth certificate but that doesnt apply for me because i wanna visit a friend not a family member. if i apply for a toursim visa then dont ask you but cant add the invitation either .


Hi I would like to know what is the difference between these two forms of type casting:  float flt=2.33; int x; x=static_cast<int> flt;   and    x=(int)flt;


I'm interested in using my laptop trackpad as a drawing tablet, i.e. using absolute rather than relative coordinates, similar to  for OSX.  The same question was asked in  in May 2010, but the question was never answered. I'm wondering if this has been done on Linux. I'm also trying to figure out which search terms to use. I searched for 'linux laptop touchpad absolute mode', and came up with  which put the trackpad in absolute mode. but I'm really looking for a program which uses the absolute positions rather than a driver setting.


Should I include a "back" button on a responsive website?

Do you believe there should be a back button on a responsive website or should we rely on the browser's controls?  If you believe there needs to be a button in the design...   Would you have it appear all the time or only on small (smartphone) screens? Do you have any examples of websites that do this well?   FYI I'm working on a website which is more a tool than a content website. Users will need to be logged in and they'll probably visit this website several times a week.  I've found  about the topic, and although the answer is interesting, I don't see any studies/articles to support the points that are made.  Edit: there is a  about this but it's nearly 7 years old so it's probably not relevant anymore


Cast Enlarge on a vial of acid then Catapult it. 8X damage?

My wizard wants to do a spell combo, it will take two turns. Enlarge/Reduce then Catapult  Cast enlarge on a vial of acid.  It weighs 1 pound and per the spell description it will grow to 8 pounds.  So it will have 8 times the volume and therefore it will do 8 times the damage. 16d6 instead of 2d6.  How to deliver it?  Cast catapult on the large vial at level 2, because it weighs 8 pounds now, doing 4d8 damage + 16d6 acid.  A whopping 128HP max.  Average 74.5 (if it hits) The 5E Player's Handbook page 237. says  The target's size doubles in all dimensions, and its weight is multiplied by eight  The acid vial will weigh 8 times as much so I am simply assuming that there is 8 times the amount of acid Does this work?  If not, why?


Sophix tablet will not work without an SD card

My Sophix tablet was working without the SD card, but now the camera will not work. I get the following error message:     Insert a SD card before using.


I am building binary classification models to fit my data and do prediction. Some of the variables have many levels, like the workclass variable below. So I am considering combine some levels into one. For example, I can combine "Federal-gov", "Local-gov", and "State-gov" into one level called "gov". However, I have two questions here.    On what circumstance should I combine levels? How can I know it probably will improve my model?   If I think doing so will be useful, how can I know that some levels are similar enough so I can combine them? Do I do any tests? How to check the similarity?    Thanks.   > summary(census$workclass)      Federal-gov        Local-gov     Never-worked          Private     Self-emp-inc Self-emp-not-inc               960             2093                7            22696             1116             2541         State-gov      Without-pay             NA's              1298               14             1836


How to lead a moving target from a moving shooter

I saw this question: .  My situation is a little different though.   My target moves, and the shooter moves.  Also, the shooter's velocity is added to the bullets' velocities, i.e. bullets fired while sliding to the right will have a greater velocity toward the right.   What I'm trying to do is to get the enemy to be able to determine where they need to shoot in order to hit the player.  Using the linked SO solution, unless the player and enemy are stationary, the velocity difference will cause a miss.  How can I prevent that?      Here is the solution presented from the stack overflow answer.  It boils down to solving a quadratic equation of the form:  a * sqr(x) + b * x + c == 0   Note that by sqr I mean square, as opposed to square root. Use the following values:  a := sqr(target.velocityX) + sqr(target.velocityY) - sqr(projectile_speed) b := 2 * (target.velocityX * (target.startX - cannon.X)       + target.velocityY * (target.startY - cannon.Y)) c := sqr(target.startX - cannon.X) + sqr(target.startY - cannon.Y)   Now we can look at the discriminant to determine if we have a possible solution.  disc := sqr(b) - 4 * a * c   If the discriminant is less than 0, forget about hitting your target -- your projectile can never get there in time. Otherwise, look at two candidate solutions:  t1 := (-b + sqrt(disc)) / (2 * a) t2 := (-b - sqrt(disc)) / (2 * a)   Note that if disc == 0 then t1 and t2 are equal.


Skipping acquire of configured file in ubuntu 20.04 LTS

I have recently updated to Ubuntu 20.04 and I am a bit fresh user for ubuntu. after installing postgresql 12 I ran sudo apt-get update it says  N: Skipping acquire of configured file 'main/binary-i386/Packages' as repository 'http://apt.postgresql.org/pub/repos/apt focal-pgdg InRelease' doesn't support architecture 'i386'   I have no idea how to solve this!  can anybody help me solve this please? Thanks in advance!


As an alternative to the other FAQ format being fleshed out here on Meta Stack Exchange, I'd like to propose something far more terse that covers the bare essential mechanics of being a moderator.   Feel free to add more questions, but keep them short: this isn't the place to get into complex moderation issues, but for an executive summary of what it is to be a moderator.  To add a new section, create a new answer and link to it in the index below.  Index:               See also:


When/why is the sqroot of the variance not a good estimator of the standard deviation?

From the (excellent) Schaum's Outlines for Probability and Statistics an example from the Estimation Theory chapter shows us that the typical estimation of the variance does provide an unbiased and efficient estimation of the true variance.  Yet the sqroot of that value is not so for the true standard deviation.  Then .. why?


Addressing of flagged posts which need moderator intervention

Specifically, when a post is flagged as in need of moderator intervention what does it mean? A while ago, this happened:    Little backstory:  I asked a question which was related to a question supplied in the comments but did not answer me. Following that, I received a private feedback to review if that answers my questions or not. Obviously, I clicked on no and pressed submit. Also notified the user who marked it as duplicate and edited the question to make it look pointed towards the author's intent(me). After a few hours, I saw my post taken down as a [duplicate] and Comments on the post deleted?. Upon flagging the post for moderator intervention, it was declined with the above message. No custom comments were put as well. This of course looks like a custom message, but was my flag a standard one?  I have read the thread  but unfortunately it's a continuation to :  and has answers which genuinely could not address what I have asked.


I am trying to find all matching answers in a list but it isn't working

I am learning programming by myself. In my code, I am practicing nested looping, and I am doing an exercise to see if I can find all matching numbers from a list. However it is returning only the first number, and it is not going through the whole list, Can someone please help? Thanks in advance   mylist = []  def intersection(lst1, lst2):   for n in lst1:     for o in lst2:       if n == o:         mylist.append(n)         return mylist


Normal operator with real spectrum is hermitian.

Consider a normal operator on a complex Hilbert space with its spectrum contained in the real line. Show that the operator is hermitian without using the spectral theorem.  What I have tried- Since the spectrum is inside the real line, the boundary of the spectrum as a subset of the complex numbers is the spectrum itself. Hence the spectrum is equal to the approximate point spectrum. I have been unable to proceed further.


A lot of command-line utilities can take their input either from a pipe or as a filename argument. For long shell scripts, I find starting the chain off with a cat makes it more readable, especially if the first command would need multi-line arguments.  Compare  sed s/bla/blaha/ data \ | grep blah \ | grep -n babla   and  cat data \ | sed s/bla/blaha/ \ | grep blah \ | grep -n babla   Is the latter method less efficient? If so, is the difference enough to care about if the script is run, say, once a second? The difference in readability is not huge.


XeLaTeX and href to a movie file with an image placeholder

After trying unsuccessfully to integrate a video in my beamer presentation (but that’s because there is no or badly working support from open-source PDF viewer mostly), I’ve decided to switch to hyperref’s href command as follow:  \documentclass{beamer}  \usepackage{hyperref}  \begin{document}  \begin{frame}     \href{run:film.mp4}{\includegraphics[width=\linewidth]{placeholder.jpg}} \end{frame}  \end{document}   But, the resulting frame seems to have no clickable object. I’ve also tried in an article document, and it resulted in a tiny cyan square (that is hyperref boxing of links) in the bottom left of the placeholder picture.  If I use pdflatex instead or a text in place of the placeholder picture, it works. Any idea?  P.S.: I’ve seen , but it’s not the same issue and I’m using TeX Live 2017, so…


/bin/bash -c "export DISPLAY=:99", how to handle colon

How to set the display   /bin/bash -c "export DISPLAY=:99"  or   /bin/bash -c 'export DISPLAY=:99'   Both are not working. Colon seems to be creating the issue. I am not sure how to fix this. After checking the env DISPLAY variable is not seen to be set. Can anybody please help


How to add citation for a whole paragraph?

If I write a report and a whole paragraph is based on one source but not cited verbally it seems unnecessary to include the reference after every sentence:  Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua (source 1). Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat (source 1).  Now I found a Phd thesis that puts the reference after the last dot of the paragraph to indicate that it is based on this very source:  Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. (source 1)  Is this a common practice? Is it generally understood? What are other ways to add the reference for a whole paragraph?


How much hard drive space to install MYSQL, PHP7 & nginx?

I'm provisioning a server, I want a rough estimate on how much HD space I would need.  I want to install mysql, PHP7 and nginx, plus a handful of small websites.   How much server space would I need to be able to do this?


I plan to self-learn Algebraic Geometry. I have an undergraduate degree in Math. I cannot find a clear answer on what the clear textbook could be. There are also some notes online on the subject, like Gathmann and Milne.


Given that the HTML

 content 1

 content 2

 content 3

   render as   content 1 content 2 content 3   My question:   Is there a way to render it as below by using CSS only without changing the HTML part.  content 1 content 3 content 2


For the binomial distribution, why does no unbiased estimator exist for $1/p$?

Suppose that $X$ ~ $Binomial(n,p)$ for $0 < p < 1$  Why does no unbiased estimator exist for $1/p$?  My approach:  We try to find the structure of $E_p(U(x))$, where $U(x)$ is any estimator of $1/p$.  Now, we will have:  $\sum{U(x)\binom{n}{x}p^x(1-p)^{n-x}}<\sum{U(x)\binom{n}{x}}=M(n)<\infty$  so that the expectation is bounded above. So this is supposed to mean that if $p < 1/M(n)$,  then the expectation cannot attain $p$ but I am not sure why the above argument even makes sense and what being bounded means for the expectation.


Java: Object references and re-assignments

From Core Java for the Impatient:      a variable can only hold a reference to an object ...   and I try it out like this and it seems to work:   public class Person{     public String m_name;     public int m_age;      Person (final String name, final int age){         m_name = name;         m_age = age;     }      public static void main(String[] args){         Person a = new Person("John", 45);         Person b = a;          System.out.printf("Person a is %s, aged %d\n", a.m_name, a.m_age);         System.out.printf("Person b is %s, aged %d\n", b.m_name, b.m_age);          a.m_name = "Bob";          System.out.printf("Person a is now %s, aged %d\n", a.m_name, a.m_age);         System.out.printf("Person b is now %s, aged %d\n", b.m_name, b.m_age);     } } /*Output: Person a is John, aged 45 Person b is John, aged 45 Person a is now Bob, aged 45 Person b is now Bob, aged 45*/   However, it doesn't seem to work for just String objects or primitive types (though, admittedly latter are not objects in the sense of being class instances):   String aS = "John"; String bS = aS; aS = "Bob"; System.out.println(aS + '\n' + bS);  /*Output: Bob John*/  int a = 10; int b = a;  a = 5;  System.out.printf("a = %d, b = %d", a, b);  /*Output: a = 5, b = 10*/   I'm wondering why this dichotomy? Thanks   ps: Person class attributes public to avoid mutators, accessors for this simple example


How to factorize $x^4+2x^2+4$ to a product of polynomials with real coefficients?

How do you factor   $$x^4+2x^2+4 $$   so it can be written as  $$ (x^2+2x+2)(x^2-2x+2) $$


Do I need a visa to transit through South Korea? Vietnamese passport, depart from Taipei

I am Vietnamese and living in Taiwan. I would like to check if I could enter Korea without a visa as transit program. I got a physical Japan visa.        Transit tourists bound for another country Eligible countries:         Applicable to all countries (except for Cuba, Macedonia, Syria, Sudan   and Iran) that are not granted visa-free entry into Korea.      Applicable to…:   - Those with a visa* or a re-entry permit for follwing any 5 countries: U.S., Japan, Canada, Australia, or New Zealand. *except   those who hold Group travel visa to Japan          Those traveling FROM or TO any one of the five countries mentioned above, whose final destination is not Korea.         Requirements      Must have a confirmed onward flight ticket for departure within 30   days after entering Korea, in addition to having no record of criminal   offence in the five countries mentioned above.    is the reference link


Proving $\sum_{k=0}^{n}k{n\choose k}^2 = n{2n-1 \choose n-1} $

[Corrected question]  I'm struggling at proving the following combinatorical identity: $$\sum_{k=0}^{n}k{n\choose k}^2 = n{2n-1 \choose n-1} $$ I would like to see a combinatorical (logical) solution, or an algebraic solution.


Why did the hash marks in American football get moved inwards in 1935 and 1945?

According to Wikipedia,  were introduced in 1932, at which time they were placed 10 yards in from the sidelines.  They have since migrated inward to 15 yards in 1935 and 20 yards in 1945, ending up in 1972 at their current position of 23 yards 1 foot 9 inches in from the sidelines. The 1972 movement is explained in , but what were the reasons for the 1935 and 1945 movements?


Show that every subgroup of the quaternion group Q is a normal subgroup of Q

How should I start to show this. Can anyone give the specific steps?


Does a HDMI-to-DVI (dual link) adapter exist? I don't care about the price

My monitor supports full-resolution display (2560x1440) only when connected to through either the DVI-D dual link port, or the DisplayPort.  My laptop, though, has neither of these two kinds of output. Instead, all it's got is a HDMI port (which is version 1.3, and I also read that the laptop's graphics chipset supports 2560x1440 at 60Hz).  So I'm wondering whether anyone has ever seen an HDMI-to-DVI dual link adapter, which will carry my ultra-highres signal to the monitor I just bought. So far I haven't seen any, and don't even know whether such an adapter (which I understand would have to be active, USB-powered and expensive (but I don't care)) exists.


Linux system equivalent to MS-DOS .bat file

I would like to write files that when opened open a terminal window and perform a series of commands, the reason for this is I want to eventually schedule them to run hourly, daily etc, and some of which I want to eventually run as background processes (data mining) continually.  I'm really sorry in advance if I am difficult to understand here, I am very amateur as far as computer science and programming is concerned, so I am just describing my objectives as best as I can without knowing the formal terminology.


My mother is currently in the United States on B2 visa and her 1-94 expires on 10-June. Since she has been an asthmatic patient for the last 30 years, I am really worried about her traveling back to India during this covid-19 situation hence I plan to apply for I-539 extension.Some question regarding the same :  1) What are the chances of her extension getting approved given her medical and current covid-19 condition ?  2) If her cases gets denied and leaves united states before her I-94 expires, will her visa still be valid?  3) What happens to her visa status if she leaves the country while her case is still pending and her I-94 has expired ? Do I have to revoke the cases in this situation ?


What is the practical purpose of a lens hood if any?

If a hood is to block unwanted light coming from the sides of the lens in use, because such light is detrimental to the picture taking, then hoods would be used at all times,because there almost always be light hitting the lens from all angles,  however hoods are not used that much.


I'm using this code   \begin{center} \begin{tabular}{ | l | l | l | p{5cm} |} \hline Day & Min Temp & Max Temp & Summary \\ \hline Monday & 11C & 22C & A clear day with lots of sunshine.   However, the strong breeze will bring down the temperatures. \\ \hline Tuesday & 9C & 19C & Cloudy with rain, across many northern regions. Clear spells  across most of Scotland and Northern Ireland,  but rain reaching the far northwest. \\ \hline Wednesday & 10C & 21C & Rain will still linger for the morning.  Conditions will improve by early afternoon and continue  throughout the evening. \\ \hline \end{tabular} \end{center}   From directly  but its causing the flow of table to shadow text of other side of the page. How to make sure that it takes full width of page and make sure no text hide or flows it.


Why are higher-end freewheels so much louder when coasting?

I tend to ride relatively modest gear (Tiagra/Ultegra), but when I'm riding near higher-end bikes, I sometimes notice that the clicking sound that comes from their cassette/free-wheel while coasting seems to be much louder and more distinct than on my bike.  Why is this?  Intuitively, one would expect that a quieter drive-train would be an indicator of greater efficiency, but that doesn't seem to be the case here.  Is it something to do with different construction, or materials?  Can you get 'quiet' high-end cassettes, or is being noisy while coasting the price you must pay for being efficient while pedaling?


Can an Arcane Trickster use Mage Hand Legerdemain to attempt to steal an unheld weapon?

It's pretty obvious a straight-up disarm would not work, as this requires an attack roll and the mage hand can't attack, but can they grab a bow, hand crossbow, etc. while the opponent is wielding something else? This is basically retrieving an object so perhaps contested by their Perception roll to check if they notice and stop it from happening?  This has some obvious synergy with, for example, the booming blade spell and Mobile feat, where if they want to be able to attack they have to move and trigger extra damage or pull out a ranged weapon.


How can i drive a 5v 120VAC 80mA with 15A contacts with a raspberry pi?

I don't have a very good knowledge of electrical engineering yet but I'm working on it. I will like to know as simple as possible, how can i drive a latching relay that needs about 70-90mA if the raspberry pi can only deliver about 40mA. I need to find a relay that can handle home appliances but can be controlled by the raspberry pi.


Infinite Degree Algebraic Field Extensions

In I. Martin Isaacs Algebra: A Graduate Course, Isaacs uses the field of algebraic numbers $$\mathbb{A}=\{\alpha \in \mathbb{C} \; | \; \alpha \; \text{algebraic over} \; \mathbb{Q}\}$$ as an example of an infinite degree algebraic field extension. I have done a cursory google search and thought about it for a little while, but I cannot come up with a less contrived example.   My question is     What are some other examples of infinite degree algebraic field extensions?


Is it possible to get admitted to a MS program with funding if I have a poor GPA but good GRE scores?

Many university in North America or in Europe offer fundings for masters program .  But it only for those students who have a good CGPA in undergraduate examination .I  have completed my bachelor degree in computer science and engineering . I have a very poor cgpa  . Is there any possibility that I can get myself admitted in those institution for masters program with fundings . I have heard that a good GRE score will help a lot . Is it true ? Can I get funding if I have a good GRE score  once again I repeat I have a very poor cgpa .


Where can I find data stored by a Windows Service running as "Local System Account"?

I'm using a service which stores data on disk. The service is running as "local system account".  Where is the stored data for that system user?  I'm thinking about C:\Documents and Settings\Default User but I'm not sure about that.  Can someone confirm that?


Is the Riemann integral of a strictly positive function positive?

In the proof  a strictly positive function in $(0,\pi)$ is integrated over this interval and the integral is claimed as a positive number. It seems intuitively obvious as the area enclosed by a continuous function's graph lying entirely above the x-axis and the x-axis should not be zero. But how can I prove this formally?   If the function is positive over a closed interval apparently  (link goes to page 147 in Theories of Integration by Kurtz and Swarz). This has further confused me. Can someone please clarify my doubt.     Thanks


How do I start over? (newbie goof: now I need to start fresh with MySQL)

I'm just starting with MySQL (version 5.7.20 on Xubuntu 16.04), and in playing around with it I changed the root password.  Now I can't log in as root -- I either forgot the password or didn't set it to what I thought I did.  This is my home hobby system, so I'm the only user.  I may as well start over.  But it's not clear to me how to do that.  On Ubuntu there are about 9 or 10 mySQL packages involved, and I'm not sure I can uninstall all of them cleanly.  I'm happy to just trash the database if I only knew the commands to start with a new one.  I could use some advice, preferably from someone who knows how it works on Ubuntu and it's variants, as these packages are managed by Canonical and are not necessarily like even the Debian ones.


Find $$\sum_{r=2}^{\infty}\ln\left(1-\frac{1}{r^3}\right)$$  I solved the simpler versions of these: $$\sum_{r=2}^{\infty}\ln\left(1-\frac{1}{r}\right)\;\;,\;\;\sum_{r=2}^{\infty}\ln\left(1-\frac{1} {r^2}\right)$$ by factorizing which yields a telescoping sum. However the cube version certainly breaks this trend. What else can be done here? Does a closed form exist?


With ubuntu 19.10 I have been attempting to pair my Airpods with my laptop. There seems to be a problem with pairing and system is unable to add them as Bluetooth device. This happened after an upgrade from 19.04. Changing ControllerMode in /etc/bluetooth/main.conf seems to have no affect. Any help appreciated.


Windows 10 - Users already logged in at boot

Since the recent Fall Creators Update I'm facing a strange behavior while using Windows 10. My brother and I are using different accounts, both protected by password. When I turn on my PC and sign in, an automatic startup program (the ) warns me that it can't start since another user on the same computer is using that app. I thought that it was impossible, my brother's account can't be active if I just turned my PC on.  Actually, if I press the start button and the user icon, it says that my brother is signed in.    Ok, he must have turned the PC off without properly disconnecting the account, I thought, right?  So I let my brother log in his account, sign out, turn the PC off, turn it on again, log in my account. Same problem, his account is already signed in. Without even entering the password.  The same happens if he is the one to login first after booting, he sees me already signed in. If I switch account to mine, I can clearly see that my startup programs are already started and ready.  How is this possible? Windows is booting up accounts without even putting the password in?


Is the normal force smaller than gravitational force due to earth's rotation?

In physics class we learn that the normal or contact force exactly equals the force of earth's gravity pulling you to the center of the Earth and thus cancel each other out. I thought that the normal force does not exactly equal the force of gravity on an object.   The earth is rotating around its axis. That means that, for example, a book lying on a table has no constant velocity since its direction of motion is constantly changing with the circular motion around the Earth's axis. The centripetal force due to this rotation, for a book with mass of 1 kg is given by: $F=\frac{mv^2}{r}$. The speed of the rotation is 465.1 m/s and the radius 6,378,000 m. So this should give a force of around 0.034 N. This means there is a net force.   I thought this would mean that the normal force does not exactly cancel out the gravitational force. Is this true? For example does the normal force on a book, with a gravitational force (on the equator) of $9.78 m/s^2$ and thus a force of $9.78 N$ equal $9.78-0.034=9.746 N$ (or is it that if one talks about the gravitational acceleration, this effect has been taken in account? That is to say, when we talk about gravitational acceleration do we mean an experimental number, so that this effect has been taken in account, or the theoretical acceleration without the effect)? Could this effect be compared with the effect that you are being pushed to the side when a car makes a curve and that the book is like this ´tilt´ a bit upwards?  Thanks in advance


I could not find a definitive answer to this question.  When using U.S. (or US) in a sentence, would it be more appropriate to say: “The U.S. were founded” or “The U.S. was founded”  I know that the grammatical number of USA is widely accepted as singular, but could not find anything about U.S. (or, by extension, US).


Prove that $\frac{x+y}{1+xy}$ is an Abelian Group

Let $I=\left]-1,\ 1\right[$ be an interval, and $\left(I,\ \star\right)$ be a magma such that:  $$\left(\forall\  \left(x,\ y \right) \in I^2\right)\ x \star y=\frac{x+y}{1+xy}$$  I need to prove that $\left(I,\ \star\right)$ is an Abelian group.  A simple way to prove it is by checking that the magma $\left(I,\ \star\right)$ satisfies the group axioms including commutativity.  Based on the following statement I would like to approach that problem:  Let $f$ be a homomorphism from $\left(X,\ \perp \right)$ to $\left(I,\ \star\right)$, then the algebraic structure of $\left(I,\ \star\right)$ is exactly the algebraic structure of $\left(X,\ \perp \right)$  So I would like to find out a usual Abelian group - ex. $\left(\mathbb{R},\ +\right)$ - and a homomorphism $f$ from that group to $\left(I,\ \star\right)$.  Assume that $f$ is a homomorphism from $\left(X,\ \perp \right)$ to $\left(I,\ \star\right)$, then  $$\left(\forall\  \left(x,\ y \right) \in X^2\right)\ f\left(x \perp y \right)= f\left(x\right) \star f\left(y \right)$$  $$\Leftrightarrow f\left(x \perp y \right)= \frac{f\left(x\right) + f\left(y \right)}{1+f\left(x\right) \cdot f\left(y \right)}$$  I got stuck on that. Could anyone support me with some hints how to get it done.


How do I tag files with custom emblems in Nautilus?

In every previous version of Ubuntu, I'd just right click the file, hit Properties, then one of the tabs would let me add all the custom icon tags I'd like. It seems to be completely missing in Oneric, though I can still see the icons on files I've tagged previously, there's just no way to change them.


I have a shapefile with polygons and another one with points. I would like to create a new shapefile with those polygons that don't contain any point inside. I tried the function sp::over in R and it returns a vector indicating which polygons have points, but I have been unable to create the new shapefile from there.   library(sp)   polygons <-over(basins,points_proj)


I just stumbled upon this user:   His nickname is probably some emoji which my browser is unable to detect. How to mention such users?


HP Spectre x360 How do I get into the BIOS?

My HP Spectre x360 boots really fast and I can't figure out how to access the BIOS screen?


Do we have different badges in different SE sites

Do we have different set of badges in different SE sites. eg. I don't see any 'Pundit' badge in badges popup in Hinduism SE.  Also, if the above is true, then can we include the left badges in a SE site at a later stage.


What to do in Chicago during an 8-hour stopover?

We are travelling from Ireland to Kansas with an 8 hour stopover at Chicago O'Hare (arriving Thursday at 12 noon) and leaving at 8 pm.    Can we leave the airport and what would you recommend we could do with those couple of hours?


Crowdsourcing spatial data with online clickable map?

Here in northern Tanzania we are experiencing a huge  - originally those of us who saw it thought it was local but it turns out that it's very widespread. We're getting informal reports from all over, but would like to (quickly!) set up a way for people to report sightings:   A clickable map on a web page that lets people show the location of a sighting; A form that collects some other basic data; Logging of spatial points and the form data.   Ideally this could be done through a Facebook page as social media will spread this like ... well, like a butterfly migration in a high wind ;).   Any ideas?    Here's the .


Lets consider a set A. Can we prove that  there exists at least one operation * such that under it the set forms a group. May I know how to approach this question?


Reading the proof of exponential derivatives I understand this: To show that $(2^x)'=\ln 2 \cdot 2^x$ in the proof is used the limit: $$\lim_{x \to 0} \frac{2^x-1}{x}$$ My question is: ¿How do I prove that this limit exist? I don't care about its value. If I were going to prove that this limit is equal to $\ln 2$, I would need the number $e$, and again, this number is defined as the number $a$ such that: $$\lim_{x \to 0} \frac{a^x-1}{x} = 1$$ In another words if I know that for some constant value $a$ the limit: $$\lim_{x \to 0} \frac{a^x-1}{x} $$ exists, let's say it's a number $L$ then I could find all the limits like these in function of $L$, But what makes obvious that this limit exist?


Install VB6 (Visual basic 6 ) without using wine

How to install VB6 in Ubuntu 17.10 without using a wine, if Visual studio supports to VB6 codes then how to add extension in visual studio.


Decoding the Playfair cipher with a crib

I have a Playfair cipher text and I know a portion of the text (one world). How can I decode the cipher from here? Thanks.


When i am running command sudo apt-get update, i am facing following problems :  W: Failed to fetch http://in.archive.ubuntu.com/ubuntu/dists/vivid/InRelease    W: Some index files failed to download. They have been ignored, or old ones used instead.   What can be the possible solution here?


If $\alpha = \frac{2\pi}{7}$ then the find the value of $\tan\alpha .\tan2\alpha +\tan2\alpha \tan4\alpha +\tan4\alpha \tan\alpha.$

If $\alpha = \frac{2\pi}{7}$ then the find the value of $\tan\alpha .\tan2\alpha +\tan2\alpha \tan4\alpha +\tan4\alpha \tan\alpha$   My 1st  approach :   $\tan(\alpha +2\alpha +4\alpha) = \frac{\tan\alpha +\tan2\alpha +\tan4\alpha -\tan\alpha \tan2\alpha -\tan2\alpha \tan4\alpha -\tan4\alpha \tan\alpha}{1-(\tan\alpha \tan2\alpha +\tan2\alpha \tan4\alpha +\tan\alpha \tan4\alpha)} $  $\Rightarrow 0 = \frac{\tan\alpha +\tan2\alpha +\tan4\alpha -\tan\alpha \tan2\alpha -\tan2\alpha \tan4\alpha -\tan4\alpha \tan\alpha}{1-(\tan\alpha \tan2\alpha +\tan2\alpha \tan4\alpha +\tan\alpha \tan4\alpha)} $ which doesn't give me any solution.   My IInd approach :   U\sing Euler substitution :   \since $\cos\theta +i\sin\theta = e^{i\theta} $.....(i) and $\cos\theta -i\sin\theta =e^{-i\sin\theta}$....(ii)  Adding (i) and (ii) we get $\cos\theta =\frac{e^{i\theta} +e^{-i\theta}}{2}$  and subtracting (i) and (ii) we get $\sin\theta =\frac{e^{i\theta} -e^{-i\theta}}{2}$   By u\sing this we can write : $$\tan\alpha .\tan2\alpha +\tan2\alpha \tan4\alpha +\tan4\alpha \tan\alpha$$ as $$\frac{1}{4}\left[ (e^{\frac{i2\pi}{7}} -e^{\frac{-i2\pi}{7}}) (e^{\frac{i4\pi}{7}} -e^{\frac{-i4\pi}{7}}) + (e^{\frac{i4\pi}{7}} -e^{\frac{-i4\pi}{7}})(e^{\frac{i8\pi}{7}} -e^{\frac{-i8\pi}{7}}) + (e^{\frac{i8\pi}{7}} -e^{\frac{-i8\pi}{7}}) (e^{\frac{i\pi}{7}} -e^{\frac{-i\pi}{7}})\right]$$  $$\large= e^{i\frac{6\pi}{7}}-e^{\frac{i2\pi}{7}}-e^{\frac{-i2\pi}{7}} +e^{\frac{-i6\pi}{7}} +e^{\frac{i3\pi}{7}}-e^{\frac{-i5\pi}{7}}-e^{\frac{i5\pi}{7}} +e^{\frac{-3\pi}{7}} +e^0 -e^{\frac{i2\pi}{7}} -e^{\frac{-i2\pi}{7}}+e^0$$  Can anybody please suggest whether this is my correct approach or not. please guide further... Thanks.


Is it a good practice to define C++ functions inside header files?

I'm wondering if it's a good practice to store C++ regular functions, not methods(the ones in classes) inside header files.  Example:  #ifndef FUNCTIONS_H_INCLUDED #define FUNCTIONS_H_INCLUDED  int add(int a, int b) {    return a + b; }  #endif   And Use it like this:  #include <iostream> #include "Functions.h"  int main(int argc, char* args[]) {     std::cout << add(5, 8) << std::endl;     return 1; }   Is this a good a good practice? Thanks in advance!


How do I get windows version as a variable?

I'm making some batch files to personalise my windows installations faster, but I need my batch to take a road depending on which Windows version it's running on.  If i could get the windows version into a variable i could build a conditional to take the right path.  I've been looking for an answer on google and even here but... the answers i've got dont meet what i need.  could someone help me please?...


What are you supposed to use to write in Latex? There doesn't seem to be any application akin to Word or Google Docs

I am new to Latex (technically not "new" - I got my interest from the Maths Stack Exchange, where I absorbed some Latex typesetting skills for maths). Hopefully, this type of question is allowed on this SE: basically, where do I start? I initially thought Latex was primarily for scientific typesetting for maths and chemistry etc only. ie recursive fractions, square roots, chemical equations which are impossible to typeset without using the "\blahblah" command. But I really like the aesthetic and simplicity of Latex documents which I have seen in thesis and papers. I am actually very confused as to how this whole thing works - but hopefully there is a guide somewhere? I thought that there would be an app to make Latex documents like you do in Word but it seems that there are so many different downloads and extensions you have to get. Additionally, it seems very complex and overkill to write stuff like \startdocument, put an "&" sign whenever you want a new sentence, and especially tables get very complex when Word does it instantly. Is it designed for everyday use? I am a school student but it would be nice to do homework in Latex (it seems only formal documents are in Latex, however). I have a mac and am just using the online Overleaf, but why are there so many more online website to do the same thing? (sorry I am not sure what tag to use)


Convergence of exponential Brownian martingale to zero almost surely

Define the exponential Brownian martingale as $N_t = \exp\left\{a W_t - \frac12 a^2 t \right\}$ which is a martingale with respect to the natural filtration of $W$ which stands for a standard Brownian motion.  I now want to prove that $N_t \rightarrow 0$ a.s. for $t \rightarrow \infty$. As $N_t$ is a martingale it is by definition in $L^1$ hence Doob's martingale convergence theorem tells us that there exists a $N_\infty \in L^1$ such that $N_t \rightarrow N_\infty$ a.s., but how could I prove that $N_\infty \equiv 0$? Any help is greatly appreciated!


What to do about a hacked WordPress website and server?

My WordPress website has been hacked.  Google sent me an email stating that the site would be listed in browsers such as Google Chrome and display a warning when users visit or download certain files from your site.  I checked the server and found a bunch of folders with random characters and files that are not part of wordpress core files like add-admin.php.  I uploaded a clean copy of the website from my local pc, then I installed iTheme Security plugin.  I also changed the admin password in wordpress and changed the root pw to the server.  Luckily, nothing malicious has been done.  It looks like they are using the server to store files for sharing.  As of now, there is a folder named networkl in the root directory, I have deleted the folder but it always reappears in less than 5 minutes.  At this point I'm not sure what to do.


In Google chrome when I start typing in a text box I get auto completion for things I have use din the past, this however is only for the current letter. Is there a way I can see all of the auto complete data Google Chrome has for this text box?


How did Twitter choose their character limit?

Twitter posts are limited to 140 "characters", which turns out to mean  in UTF8 (). Was this determined by a (likely outdated) technical limitation, or is there a published UX rationale?


What's the best way to store class variables in PHP?

I currently have my PHP class variables set up like this:  class someThing {      private $cat;     private $dog;     private $mouse;     private $hamster;     private $zebra;     private $lion;      //getters, setters and other methods }   But I've also seen people using a single array to store all the variables:  class someThing {      private $data = array();      //getters, setters and other methods }   Which do you use, and why? What are the advantages and disadvantages of each?


Is there any lingual way to differentiate between the family that I’m a child of and the family that I am a parent of? (I.e., the first family consists of my parents, my siblings, and me; the second one consists of my spouse, my children and me.)


ModernCV Remove horizontal line in sections

I want to write my cv with moderncv-Classic style. Can you tell me, how I can remove the horizontal line in the left of each section?


In an email beginning with 'Hello', should one put a vocative comma following the first word?

Is it technically correct to write  Hello, Bob,  It looks wrong to have a comma immediately after the first word, but given that "Hello" is very syntactically different from "Dear/My Dear", it seems that a vocative comma is required.  Is this seemingly wrong practice technically necessitated when beginning an e-mail with 'hello', 'hi', etc?


In the Harry Potter books, what do wizards wear under their robes?

In the movies, they wore ties and really nice shirts, but I don't think that's how it was in the books?    What do wizards and witches wear under their robes?


Is it possible to trigger OOM-killer on forced swapping?

Is it possible to have the system preemptively swap out inactive pages (vm.swappiness), but invoke the oom-killer when the system runs out of RAM (as opposed to running out of memory) and is forced to swap?  The ultimate goal is to keep the system from grinding to a halt when it starts thrashing the disk because of major page faults, but still let inactive pages get swapped out.  Another desire would be to configure how much swap memory the system is forced to use before oom-killer triggers. This way the system can dip into swap just a little bit, as long as it doesn't go too far.  Or I could set such a threshold to trigger oom-killer before using all the RAM so there will always be room for the file system cache (and thus avoid more disk thrashing).  It doesn't seem like this would be that hard to do. It seems like you could just tell the oom-killer to trigger when the system has X ram used/free. But this is why I'm asking; I don't know.  For clarification, I am not looking to turn off swap, or adjust the vm.swappiness parameter


Momentum conservation in vertical direction. Confusion

I was solving a problem from "An Introduction to Mechanics" by Kleppner and Kolenkow. The problem says..     A circus acrobat of mass $M$ leaps straight up with initial velocity $v_0$ from a trampoline. As he rises up, he takes a monkey of mass $m$ off a perch at height $h$ above trampoline. What is the maximum height attained by the pair?   Now I tried to solve the problem in many a way, but my answer didn't match. Ultimately, I used the conservation of momentum in the vertical direction and then the answer came out right. But previously I understood that momentum conservation cannot be applied in direction where there is a net external force acting on system. And here in this sum, gravity (an external force) is surely acting on the Acrobat-Monkey pair downwards. So can anyone tell me, how is the application of momentum in vertical direction justified in this problem, but not in problems involving projectile motion?


package expl3 Version 2018/02/21 not installed after update with TeX Live Utility

Dear Ladies and Gentlemen,  After updating TeX Live with the TeX Live Utility, today, XeLaTeX does not compile any file any more, and gives in the console the warnings:  “package expl3 Version 2018/02/21 not installed”, and “Package xparse Error: Support package l3kernel too old” and says: “Please install up to date version of l3kernel using your tex package manager from CTAN“. It seems that with the new update something which has to be updated also has not been updated. Does anyone know what to do?  With best regards, Jens Bakker


Prove that a sequence is a Cauchy sequence.

The question is this.     Let $(s_n)$ be a sequence such that   $$\left|s_{n+1}-s_n\right| < 2^{-n}, \forall n \in\mathbb N$$   Prove that $(s_n)$ is a Cauchy sequence and hence convergent.   My proof is below.  Proof. Let $\epsilon > 0 $ and $N = \dfrac{\ln\left(\frac{1}{\epsilon}\right)}{\ln(2)}$. Then, $\forall n > N = \dfrac{\ln(\frac{1}{\epsilon})}{\ln(2)}$ implies  $$n\ln(2) > \ln\left(\frac{1}{\epsilon}\right)$$ $$2^n > \frac{1}{\epsilon}$$ $$\epsilon > \frac{1}{2^n} > \left|s_{n+1}-s_n\right|$$Q.E.D.  Is this ok??


Minimum number of characters in the last line of a paragraph

Last line of paragraph should end with a minimum of five characters of the word. Is it possible to obtain this with LaTeX ?


Is Randall Munroe's "what-if" xkcd correct that magnified moonlight can't get things hotter than the moon?

Note: I am NOT asking if moonlight can be used to start a fire. I am asking whether these particular arguments in support of the claim that it cannot are correct. i.e. I'm looking for an answer that addresses the physics of these arguments specifically.  On , the following claims are made:  You can't start a fire with moonlight no matter how big your magnifying glass is.  General rule of thumb: You can't use lenses and mirrors to make something hotter than the surface of the light source itself. In other words, you can't use sunlight to make something hotter than the surface of the Sun.  Lenses and mirrors work for free; they don't take any energy to operate. If you could use lenses and mirrors to make heat flow from the Sun to a spot on the ground that's hotter than the Sun, you'd be making heat flow from a colder place to a hotter place without expending energy. The second law of thermodynamics says you can't do that. If you could, you could make a perpetual motion machine.  (more claims which I'll omit here)   I neither believe the claim nor follow any of the reasoning. First, I don't get the thing about the perpetual motion machine:  If this is regarding the first law of thermodynamics (conservation of energy), then it's perfectly possible to lose energy while still heating up an object, which would avoid perpetual motion, so I don't get the argument.  If this is regarding the second law of thermodynamics (increasing of entropy), then it's also invalid because the disorder in the system is still increasing.  If this is about something else, then I don't know what that is.   Second,  is a video of a guy using a mirror he can hold in his hand to light paper on fire. Clearly the mirror itself isn't getting as hot as he's making the newspaper, and clearly the mirror is the one reflecting the sunlight. So how can one claim that the paper fundamentally can't get hotter than the reflecting surface? Why can't the moon's surface fundamentally behave similarly (albeit with poorer reflectivity)? Can someone explain? Is Randall confusing heat with temperature? Or maybe conduction with radiation? Or am I missing something subtle (or perhaps not so subtle)?


I have the string "SELECTOR('(namespace=''ar.com.osde.reintegros'' and eventname=''generacionReintegro'')')".  I need return the string that is between "SELECTOR(" and ")", the result should be: '(namespace=''ar.com.osde.reintegros'' and eventname=''generacionReintegro'')'.  My code with the regular expression is:  public static String extractSelector(String txt){     Pattern pattern = Pattern.compile("^SELECTOR\\((.*)\\)$");     Matcher m = pattern.matcher(txt);     String s = null;     while (m.find()) {         s = m.group(1);     }     return s; }   Where txt = "SELECTOR('(namespace=''ar.com.osde.reintegros'' and eventname=''generacionReintegro'')')"  But this always return null. Why is that?


What is the reason/intention behind not allowing unregistered users to sort questions by categories like 'votes', 'active' etc. ? Questions are sorted by only the 'newest' type of sort.  I visit many SE sites and it is really not useful if I create an account only to visit once and never use it again.


I can compile this table separately but when I want to compile the whole file, it gives me an error, which is fixed by removing \multirow.  \usepackage{multirow}  \begin{table}[htbp] \begin{center} \begin{tabular}{|c|c|c|c|p{1cm}p{1cm}p{1cm}p{1cm}p{1cm}p{1cm}p{1cm}|} \hline A & B & C & D & \multicolumn{7}{|c|}{F}  \\ \hline \multirow{ 2}{}{1} & 0 & 6 & 230 & 35 & 40 & 55 & 25 & 40 & 35 & \\ & 1 & 5 & 195 & 25 & 50 & 35 & 40 & 45 &  &  \\ \hline \end{tabular} \end{center} \label{table2} \end{table}


Visible `` tag in the "Thanks for voting popup"

After casting my votes in an election on the network, I had notice popup saying I cast my 3rd vote and thanking me for doing so. However, in the middle of the popup was a visible <br/> tag. See below.


do i (Nepali National) need visa to transit Miami airport to travel another country?

i (Nepali National) have been getting connecting flight at Miami Airport to travel Cayman Islands. do i need to obtain transit visa or not?


Is there an alternative to spreading flour when rolling the dough?

Today, when I was rolling the dough for my , I noticed that I actually need to use quite a lot of flour to prevent the dough from sticking to the rolling pin and the board. Is there a way around that, for example some substitute for flour that would work?


Suppose that $f\in L^1(\mathbb{R})$ and that $f(x)=0$ if $x\notin[0,1]$. For $n=1,2,\ldots,$ let $f_n(x)=f\left(x+\frac{1}{n}\right)$. Prove that $\|f_n-f\|_1\to 0$ as $n\to\infty$.


I need to iterate over two lists:  \begin{tikzpicture}[x=5mm, y=5mm]     \foreach \x in {0,2,...,8} {         \node[] at (\x, 0) {value};     } \end{tikzpicture}   The "value" has to be a value from the second list: {2, 3, 5, 7, 11} (yes, these are first five prime numbers).  I know, TeX is not really a programming language, but is there a way to do so?  Nesting foreach doesn't solve the problem:  \foreach \x in {0,2,...,8} {     \foreach \value in {2,3,5,7,11} {         \node[] at (\x, 0) {\value};     } }   The output looks as expected like this:    Solution (thank you Pier Paolo):  \foreach \x/\value in {0/2,2/3,4/5,6/7,8/11} {     \node[] at (\x, 0) {\value}; }


Replacing Win8 with Win7, how to wipe disk?

I have a staff member with a Win8 Asus Laptop.  They have decided they want to wipe it clean and install Windows7. There is no data on the computer they want to preserve.  So, I have a new copy of Win7 Home Premium to install on it. I've tried using custom install and selected the partition and everything seems to go fine. However, when it comes to reboot after installation, it hangs at 'starting windows'. Safemode hangs as disk.sys.   I'm leaning towards deleting all the partitions as I think there is some issue with the Win8 partitions.  What is the best way to replace Win8 with Win7 on a clean computer where there isn't any data or settings to worry about? Should I partition or wipe the whole drive? What is the best way to tackle this problem?


Be able to use NOT (complement) for a user search

You can use -foobar to search for posts that do not contain the text "foobar". You can use -[foobar] to search for posts that are not tagged with tag foobar.  It does not seem possible to exclude questions and answers posted by a specific user (is it?). How about making that possible?  Suppose I want to see questions or answers or both that have given tags and contain given content, but I want to exclude posts by myself (or by some other user).  Couldn't this be useful? Possible?


Solve  Maximize $f(x)=c^Tx$   subject to $x^TQx \leq 1$   where $Q$ is a positive definite matrix.  what is the solution if the objective function is to be minimized ?


how to get the string data in HTML tags using regex

<img src=\"https://s1.yimg.com/bt/api/res/1.2/1aLfwfzLVx7.osxsV87uog--/YXBwaWQ9eW5ld3NfbGVnbztmaT1maWxsO2g9ODY7cT03NTt3PTEzMA--/http://media.zenfs.com/en_us/News/Reuters/2016-06-20T125326Z_1_LYNXNPEC5J0TN_RTROPTP_2_FLORIDA-SHOOTING.JPG\" width=\"130\" height=\"86\" alt=\"***A woman mourns as she sits on the ground and takes part in a vigil for the Pulse night club victims following last week&#039;s shooting in Orlando\" align=\"left\" title=\"**A woman mourns as she sits on the ground and takes part in a vigil for the Pulse night club victims following last week&#039;s shooting in Orlando***\"** border=\"0\" />The Florida nightclub killer called himself an &quot;Islamic soldier&quot; and threatened to strap hostages into explosive vests in calls with police during the three-hour siege, according to transcripts released by the FBI on Monday. In a first call he made to a 911 emergency operator, Mateen said &quot;I pledge allegiance to Abu Bakr al-Baghdadi, may God protect him, on behalf of the Islamic State,&quot; referring to the head of Islamic State. The FBI and U.S. State Department released partial transcripts of the four calls with the emergency operator and crisis negotiators earlier on Monday, omitting the shooter&#039;s references to the leader of Islamic State, saying they did not want to provide a platform for propaganda.

   For the above HTML tag by using regex I am eliminating HTML tags and getting only description about news. In that descripton i.e., "A woman mourns as she sits on the ground and takes part in a vigil for the Pulse night club victims following last week's shooting in Orlando " this quoted part is missing. How to get that data also ?  This is the regex i am using to get description  String news_description = item_obj.getString("description");  String news_description_noHTMLString = news_description.replaceAll("\\<.*?>","");   Can anyone suggest me how to get that ?


Show x0 or x1 for tags with only 0 or 1 question

On the  page, the number of questions using the tag is shown for each tag, except those which are used on 0 or 1 questions.  This makes it impossible to tell which bad new tags have already been removed from their questions without duplicating someone else's effort of clicking on the tag and observing that it's unused.  I'd like to see the question count for either the 0s or 1s (or possibly both) to save time when looking through new tags.


QGIS working with Qchainage using degrees instead of meters

i'm using Qchainage on a Polygon to Line layer, and in the input dialogue there's degrees instead of meters .. and i've used trial and error to find a suitable distance ... but the issue is that not all the created points are at the same distance from each other  my process goes as follows Creating a buffer >> polygon to line >> QChainage   is there a way to input meters ?


Why is the aperture ring removed from new Nikon lenses?

Maybe I'm wrong, but I notice that Nikon's newer lenses don't have an aperture ring. For example, an older AF 35 mm f/2D is now replaced by AF-S DX 35 mm f/1.8G, or AF 50 mm f/1.8D is replaced by a newer AF-S 50 mm f/1.4G.  I never used a D-type lens, but I believe that it is much easier to rotate the aperture ring on the lens than pressing a specific button then rotating the wheel on the DSLR body when you need to adjust the aperture (and it always annoyed me to do it this way, since I often change aperture and I can't do it while keeping the camera at my face with a finger on a shutter button).  So why is the aperture ring removed more and more from the Nikon lenses?


What criteria are used to select the links that appear in the community bulletin sidebar block?

On , the number of meta posts shown on the Community Bulletin is, at moment I am writing this question, 2. Previously, there was just a single meta post linked from that block, and it was a  post; the total number of links was the same, as there was a link to a blog post more.    What are the criteria used to show the links in that block? Do the links to blog posts or event posts have the priority?  For instance, there were new posts on , and the second question linked from the block is actually the 41st question shown on the front page.    Now that the event expired, this is what the block shows, in different moments of the same day. (The screenshots have been taken at a distance of not more than 2 hours.)


Close voters can be seen by those without the privilege to do so

This is what I see from my account (which has the close vote privilege):  It says "Viewable by the post author and users with the close/reopen votes privilege," yet this is not true.      Here is evidence for that. This is what users without the close vote privilege see (which makes us think what the above said is true)     But if you click that button, well, they too can see what's forbidden:     Is this a possible bug?


How to ask multiple similar but different questions?

There have been discussion earlier if similar but different questions should all go into one question post or into several independent (which may link to each other). The general consensus is to ask several separate questions:      I fully agree on that. However, when I do it, often enough I get votes as exact duplicate.  One example:    closed as exact duplicate of    It is obviously not an exact duplicate because it asks about try_lock which does something different than lock. It still may be that the answers may be the same, however, I am not sure about that (and the people who closed it also don't, regarding to their comments).  I am wondering how I should handle it in the future. Because of such problems, I start to put several questions again into one question. But then I often don't really know what I should choose as the answer if they only answer one of the questions.  When I had them separated and the second and the second one gets closed, I am also not exactly sure what I should do if the first question was already answered but the answer does not answer my second question (see my example above -- the answer about lock does not mention try_lock at all).


what is no. of positive eigen value of symmetric matrix A with some given relationship

Suppose A is a 3*3  symmetric matrix s.t.  $$\begin{pmatrix} x & y & 1 \\   \end{pmatrix} A  \begin{pmatrix} x  \\  y\\ 1\end{pmatrix}  = xy -1 $$  let p be the no. of positive eigen value of A and q = rank(A)-p, then p=? q=?  what matrix A should be I can't find??


Cryptodefense ransom use RSA-2048. Any chance with known plaintext attack?

The "new" kind of ransomware invade your computer and crypt all your files using the RSA-2048.  Personally, I have been victim of cryptodefense: 40000 files encrypted... I'm not going to pay anything to this &? but this is a big loss. I have a lot of files in both form: crypted and uncrypted (backup from 2011...)  Is there any chance to apply a known plain text attack on RSA-2048. I read another topic and it seems that if you have two files you miss a variable (e) but is there any way to find it with more than a thousand of files?  Does that means that this is a question of calculation capacity (in that case I'm gonna wait a couple of years to have my pictures back ;-)


What happens if I attempt to delete Ubuntu itself while logged in?

What would happen if I delete the / directory while logged as root into Ubuntu?  Would I get some sort of error to the effect of Error: unable to self-destruct? Or would I actually be able to delete the directory?


To show: If every Prime-Divisor of m is a prime-Divisor of n ist, then φ(mn) = mφ(n). φ(n) is the totient-function introduced by euler.


Array.includes has worst performance in LWC lightning locker

Note: This question can be considered as extension of  BUT it is not duplicate - check at the end of this question why there is no proper alternate work-around. It seems like all latest Array functions have worst performance in locker service. According to :  But basic functions like Array.includes (and find, findIndex, etc) from latest Ecmascript (includes is from ecma 2016) are failing in LWC locker. Below is the example: parent.html: <template>     <div class="slds-theme_default slds-box">         Parent         <lightning-button label="test" onclick={test}></lightning-button>         <c-child arr={arr}></c-child>     </div> </template>  parent.js export default class Parent extends LightningElement {     @track arr = [];     test() {         this.arr.length = 0;         for (let i = 1; i <= 1000; i++) {             this.arr.push('a' + i);         }         console.log('Parent array ', this.arr.length);          const t1 = new Date().getTime();         const c1 = this.arr.includes('a422');         const t2 = new Date().getTime();         const c2 = this.arr.includes('a42222');          const t3 = new Date().getTime();          const c3 = this.arr.indexOf('a4222') > -1;         const t4 = new Date().getTime();         const c4 = this.arr.indexOf('a42222') > -1;         const t5 = new Date().getTime();          console.log(c1, c2, c3, c4);         console.log('includes => ', t2 - t1, t3 - t2, t3 - t1);         console.log('indexOf => ', t4 - t3, t5 - t4, t5 - t3);     } }  child.html: <template>     Child     <lightning-button label="test" onclick={test}></lightning-button> </template>  child.js export default class Child extends LightningElement {     @api arr;      test() {         console.log('child array ', this.arr.length);          const t1 = new Date().getTime();         const c1 = this.arr.includes('a422');         const t2 = new Date().getTime();         const c2 = this.arr.includes('a42222');          const t3 = new Date().getTime();          const c3 = this.arr.indexOf('a4222') > -1;         const t4 = new Date().getTime();         const c4 = this.arr.indexOf('a42222') > -1;         const t5 = new Date().getTime();          console.log(c1, c2, c3, c4);         console.log('includes => ', t2 - t1, t3 - t2, t3 - t1);         console.log('indexOf => ', t4 - t3, t5 - t4, t5 - t3);     } }  Below is the output:  Although below is potential solution (as mentioned in  question), child.js:     @api     get arr() {         return this._arr;     }     set arr(value) {         this._arr = JSON.parse(JSON.stringify(value));     }  But This will remove the reactivity from api valiable arr. And we end up creating one more duplicate tracked variable which just keeps bloating the code as nested components increase and thereby increasing technical debt. So, we would need a proper solution such that LWC by itself handles these functions properly


What is meant by submission to first decision? Is the decision either accepted or rejected?

Some journal submission systems are very transparent to the author to let the authors know the submitted manuscript at what stage. Recently I noticed that in the manuscript submission system of a journal number of days is written next to submission to first decision. I have been waiting for an editorial decision about the manuscript. But still, no editorial decision is not showing, or I have not received the decision email.


How is the Metric value decided in WIndows

After reading , I was wondering how the operating system 'chooses' the Metric value for a route.  I have 2 dynamically added routes for internet:        0.0.0.0          0.0.0.0      192.168.0.1    192.168.0.239     45       0.0.0.0          0.0.0.0         10.0.0.1       10.0.0.254     15   So naturally, my traffic is being routed to the gateway at 10.0.0.1 first because 15 < 45, if there are no routes on 10.0.0.1, it will be routed to 192.168.0.1 for delivery.  What I'm wondering is:  How does Windows (or any OS with a routing implementation) decide the metric value for these 2 interfaces?  I notice some people contradicting each other in the comments of the linked question when it comes to priority based on Ethernet/Wireless and the like. For this reason I want to note:   The interface with Metric 45 is a Wireless adapter The interface with Metric 15 is connected to a Hyper-V Virtual Switch hosted on the same machine.


Logical understanding of the canonical probability distribution (canonical ensemble)

I am having problems in understanding the logic of this distribution:  $P(\Psi_{j})=\displaystyle\frac{e^{-E_{j}/kT}}{\displaystyle\sum_{j'}e^{-E_{j'}/kT}}$  The book I am studying use the case of a sample in contact with a reservoir at thermal equilibrium to derive this distribution. I understand the derivation, but I don't understand the logic of the distribution itself. The aspect I'm having problem with is the fact that the lowest the energy of the sample, the highest the probability. What I don't understand is why this happens even thought there is an average energy given by the temperature which I thought should be more probable then any energy lower than this for a given particle. This doubt implies that I am looking at $P(\Psi)$ as the probability for a given particle, wich does not seem to be the case, but if I think of it as the probability for the hole sample, it makes even less sense for me since the energy should be totaly given by the temperature, so it wouldn't make sense to make a distribution of it if the temperature is considered constant.   Thanks in advance


Why does my Windows 10 Laptop fail to hibernate sometimes?

After I click 'Hibernate', my laptop does hibernate, but only sometimes. Other times, the screen immediately fades black. But then the power button stays illuminated, and 10 s later (after I clicked 'Hibernate') the screen reappears, with everything before still opened.In both cases, my laptop had the same 3 USB devices plugged.  and  didn't help:  Update on 28 July 2018 Performing the steps in , didn't help. See  for my most updated energy-report.html.


Getting the array index in a foreach loop

So I may just be completely overcomplicating this for myself but I am trying to get the index of an array in a multidimensional array.  Hopefully showing it makes more sense.  Array (     [1234] => Array         (             [Name]  => Test         )     [5435]  => Array         (             [Name]  => Test         ) )   I have a large array with different numbers as the index and I need to do a foreach through them, but I need that index number. (1234,5435)  Is there any easy way of doing this?


I met a guy on a sugar daddy dating site and we talked, I told him my situation and he said he would help.   He asked for my bank account information and I told him you can use cash app or PayPal to go through. He said his account manager deals with his finances. So I set up an account with a bank that I don’t use so that my primary account isn’t used.  Eventually he was in the process of sending me money and we had agreed on a amount that wasn't crazy. But then he asked for my address and I asked why and he said just wondering. Then said he wanted to send me a surprise for being his baby. Which I didn’t give.  Then later on he sent the money and said he sent me a bonus and that I was supposed to use that to pay his mothers caregiver, which he didn’t mention until after.  I kept questioning him and he was saying that he works in construction and he’s trusting me to carry out the errand. Then he said don’t let him down and I asked him if he was threatening me and he kept saying I need this done but didn’t really answer my question.  Am I being scammed? I’m about to change my password but is this a scam?


Can I change the ordering for grouped dock items to be static?

In the Ubuntu dock on Ubuntu 18.04, multiple windows of the same application are grouped and orange dots are shown to tell you how many windows of the application are opened. When you click on the icon, a small screen capture of each of the windows is shown.  However, these screen captures are shown in an order that's based on which window was last active on the desktop. This is something that clashes with the way I use the dock. I'm used to mentally mapping the windows to their dock positions. As such, I will often be trying to get to "the top one" and then I end up needing several clicks before I actually get to the terminal (or some other application) that I was looking for.  Is there some way to make sure that the order of these screen captures does not change whenever a window becomes active?


How can I make my macbook pro liquid proof?

As I hang around those who are toilet training, and people who really dislike macs, I'm wondering if there is any way to make my macbook pro urine proof?   Update  What about adding a waterproof case, if any exist? I'd like to be able to use it at the same time if possible.


What to do when someone other than the author changes a question to fix a substantive problem with the code

See . Someone other than the OP changed the code to address a substantial problem with the it that was addressed as part of my answer. The problem was admittedly peripheral to the core question, but it was a primary differentiator between my answer and another answer submitted at the same time.  Any suggestions on what to do in this situation? Leave it be? Edit it back? Something else?  Update: I just found , from the "Related Links" section on the right, which is pretty relevant. I have to keep remembering to check there rather than just searching for answers.


How to find (and delete) duplicate files

I have a largish music collection and there are some duplicates in there. Is there any way to find duplicate files. At a minimum by doing a hash and seeing if two files have the same hash.  Bonus points for also finding files with the same name apart from the extension - I think I have some songs with both mp3 and ogg format versions.  I'm happy using the command line if that is the easiest way.


Can bounty be automatically awarded to my answer if I put on bounty

Refering to . It says      Can I award a bounty to my own answer? No   But can you still get half bounty points through automatic rewarding. It is not clear from the above answer. Does my answer count eligible for automatic rewarding. I am hoping yes but if not, why ?  Refering to BoltClocks comment to this .   So basically it's up to the system to figure out who gets the bounty then


I'm converting some php code to python. The php code has the following for matching a surname from a string:   preg_match("/([^ ]*) *$/",$c['name'],$r);   which appears to just match whatever the last word in the string is.  Looking to convert it, I thought the following would do it:   r = re.match('([\S]+)$', c['name'])   to my mind that should match any non-space characters before the end of the string. The logic is that $ matches the end of the string, and the ([\S]+) matches any non space character one or more times before the end of the string. However that doesn't work for me (despite a site like pythex.org suggesting it should).  I've managed to get it to work using the following, but I'd like to know why the above regex doesn't work, I suspect it has to do with back-capture but I'm not really familiar with how that works.For testing I'm just using c['name'] = 'John Doe'   r = re.match('(?:.*\s)*([\S]+)', c['name'])   (in the above regex the (?:.*\s) is a non-capture group that matches repeated characters followed by a space-like character 0 or more times. It then captures any non-space-like characters that occur one or more times.)  Thanks.


I'm in a situation where my Comcast cable modem will not resolve URLs hosted locally.   Essentially, if I access my website from the same network, I cannot use www.mysite.com, but instead must use 10.0.0.14 (the local IP address).   Externally, there is no issue.    I found more info on the cause of this here:     That said... the simple solution to this is to either a) access the site using the internal IP address, or b) map the URL to the local IP address using the hosts file.  I've done b on one of my laptops, and this does work.  However, I'm looking for a more robust solution to this problem, to address accessing the site with items such as an iPad that a hosts file can't be edited on.   So the question is... Is there a way to setup a local DNS server that would "feed" a hosts file to all of the devices in the house?   Meaning...  can I configure the server in such a way that all requests are checked first and mapped to local addresses if needed?  Hopefully that's clear... please let me know if I can provide more detail.   I'm currently at a loss...  and mostly just frustrated that this is even an issue.


I installed Eclipse, openjdk6 and downloaded and extracted the sdk manager file.  Now, When I created an Android project I got the following error:  2012-06-06 18:44:40 - contactManager] /home/catia/android-sdks/platform-tools/aapt:  error while loading shared libraries: libz.so.1: cannot open shared object file:  No such file or directory   And this one when I tried to create an AVD Manager:  [2012-06-06 19:00:18 - SDK Manager] /home/catia/android-sdks/tools/mksdcard: error  while loading shared libraries: libstdc++.so.6: cannot open shared object file: No  such file or directory  [2012-06-06 19:00:18 - SDK Manager] Failed to create the SD card. [2012-06-06 19:00:18 - SDK Manager] Failed to create sdcard in the AVD folder.


I am on macOS Catalina. On a site they say that, if I am having problems, in order to be able to run the app I need to input (sudo chown -R 755 AppName.app) in the terminal. My question is: is it safe to do so? Is there a way to reverse my actions?


A roadmap to learn statistics if one has background in mathematics

I am graduated from mathematics but my degree did not contain any statistics courses. What kind of road map would one suggest to learn statistics if my next goal would be to learn statistics so well that I could help bachelor thesis writers to do the data analysis? For example, is it enough to study the books Methods and Applications of Linear Models: Regression and the Analysis of Variance, Statistical Inference and Introduction to Practice of Statistics?


I tried to prove Darboux's theorem. It is the following theorem:  Let $f: [a,b]\to \mathbb R$ be a differentiable function and let $f'(a) < \alpha < f'(b)$. Then there exists $c \in [a,b]$ with $f'(c) = \alpha$.   Please could somebody check my proof?  Define $g(x) = f(x) - \alpha x$. Then $g$ is continuous and because $[a,b]$ is compact $g$ attains its minimum on $[a,b]$. Let $x_m \in [a,b]$ be such that $g(x_m) \le g(x)$ for all $x\in [a,b]$. If $x_m \in (a,b)$ then $g'(x_m) = 0 = f'(x_m) - \alpha$ which shows the claim.   If $x_m = a$ then $g'(x_m) = g'(a) < 0$. Because $g$ is continuous and $g'(a) < 0$ there exists $\delta>0$ such that if $x \in (a,a+\delta)$ then $g(x) < g(a) = g(x_m)$. But this is a contradiction because $x_m$ is the minimum. If $x_m = b$ then again there is $\delta>0$ such that if $x \in (b-\delta, b)$ then $g(x)<g(b)=g(x_m)$ because  $g'(b) > 0$. Again this is a contradiction. It follows that the minimum is attained in the interior $(a,b)$.


List solutions of $x^{2} + y^{2} = z$ ignoring signs and order ($x > 0$ and $y > 0$).

I know there is a known way to count the number of solutions of $x^2 + y^2 = z$, . Is there an efficient way to enumerate the solutions ignoring sign and order?


PuTTY inserts random characters during a session

I recently started renting space on a remote server so that I could work on a project. I found that a relatively painless way to access it on a windows machine is through PuTTY. However, there is one thing that has always irked me when using it: for seemingly no reason random characters are sometimes inserted at the cursor.  Most of the time it is just a single tilde, but rarely it spits out what looks like some escape sequence ([[^8 or the like). It will only occur when I am focused on the window, whether I am typing or 20 feet away from the keyboard. If left for long enough, it will spit tildes at random intervals (average is about 1 minute).  Finally, this behavior seems to be inconsistant when running programs such as nano or the mysql interface: in nano, instead of inserting tildes, it will set marks (ctrl-^); in mysql, lines will become un-editable.  My question is this: Has anyone else experienced this sort of behavior in PuTTY? And if so, what can be done to prevent/correct this behavior?


Logic and Garage Band do not import audio file correctly

Today I tried to import an mp3 file to Logic, but it was weirdly speed up. I've tried both drag and drop AND Command+I, but it didn't help. Later I tried to import the file to the Logic through Garage Band, but the same problem occurred - in Garage Band, the file was in higher speed. Then, I tried to import in through Adobe Audition, but Logic doesn't want to read files imported through Audition at all. No idea what to do.


Ext$_R^n(Q,A)=0=$Tor$_n^R(Q,A)$ where $Q$ is the field of fractions of a domain $R$

I am currently working through a problem in Rotman:       Let $R$ be a domain and let $Q=$Frac$(R)$.  If $r\in R$ is nonzero and $A$ is an $R$-module for which $rA=0$, prove that for all $n\geq 0$, $\mathrm{Ext}_R^n(Q,A)=0=\mathrm{Tor}_n^R(Q,A)$.   I think I have the Tor part:  Since $Q$ is flat, Tor$_n^R(Q,A)=0$ for all $n\geq 1$.  And Tor$_0^R(Q,A)=Q\otimes_R A=0$ because: for each $\frac{t}{s}\otimes a\in Q\otimes A$, $\frac{t}{s}\otimes a=\frac{tr}{sr}\otimes a=\frac{t}{sr}\otimes ra =0$.  However, I am having trouble with the Ext part.  To do it directly I either need a projective resolution for $Q$ or an injective resolution for $A$, but I am not sure how I would resolve either of these.  Or I considered using a long exact sequence for the short exact sequence $0\rightarrow R\rightarrow Q\rightarrow Q/R\rightarrow 0$, but that didn't seem to get me anywhere either.  I have been stuck on this problem for far too long so any help or hints are greatly appreciated.


How do I parse an ISO 8601-formatted date?

I need to parse  strings like "2008-09-03T20:56:35.450686Z" into Python's datetime type.  I have found  in the Python standard library, but it is not very convenient.  What is the best way to do this?


Bash Script that connects to VPN server via openvpn, runs a program, and then disconnects from openvpn server

The operating system I am using is Ubuntu Server 10. I've been trying to cobble together a way to connect to a vpn server via openvpn using command line, run a unison profile, and then disconnect from the vpn connection - all from a bash script. Ultimately, I wanted to run this via cron job every night.  I've figured out that you can run a OpenVPN connection from the terminal by typing in the following:  openvpn --config vpn-config.ovpn --askpass pw.txt   This is done because the server isn't accessible via SSH. Afterwards, I need to synchronize files between my machine and a remote server. I planned on accomplishing this via Unison, a unison profile, and a having my SSH keys already uploaded to the server. So, after connecting to the VPN server, I planned on running this:  unison sync-files.prf   I haven't figured out how to disconnect from a VPN connection automatically. Any ideas?


Every black hole has a singularity. But the singularity is covered by a thing called 'Event horizon'or ' Schwarzchild Radius'. Our universe is originated from a naked singularity. By naked singularity, I mean that the singularity wasn't covered by the event horizon. Is it possible that a black hole has a universe in itself?


So far i have used a self written script in php using md5 hash to create the login and everything around it. I was wondering if there are some more secure alternatives i could implement in php today? What would you recomment?


The relationship of ${\frak m+m=m}$ to AC

Two simple questions: (Of course ${\frak m}$ denotes a cardinal in the weak sense in the claims below.)   Can we prove in ZF that $\aleph_0\le{\frak m\Rightarrow m+m=m}$? If not, what is the relationship of this statement for all cardinals ${\frak m}$ to AC?   The weaker principle $\aleph_0\le{\frak m\Rightarrow m}+1={\frak m}$ can be derived in ZF, and it is a well-known result of Tarski that $\forall{\frak m}\ge\aleph_0,{\frak m\times m=m}$ implies the axiom of choice, but I am not sure about the intermediate result with ${\frak m+m=m}$.  Edit: A related question: is it consistent with ZF that there exists a cardinal ${\frak m}\ge\aleph_0$ such that ${\frak m=n+p}$ with ${\frak n<m}$ and ${\frak p<m}$? It's hard to say whether ${\frak m+m=m}$ precludes this scenario.


Help us test the alpha version of our Android app

We are in the early stages of development of the official Stack Exchange Android app and we need your help with testing. To set a few expectations: there will be bugs, crashes, and missing features, all of which will be fixed in .    We are initially targeting Android devices running  (Android 4.1 or higher) starting with phones (up to ~5 inch) and eventually moving our way to tablets.    To register for alpha testing .  After you register we will send you an invite to a private Google community where you can find a link to download our app directly from the  store. The invitations will be sent out in waves, so if you don’t get an invite immediately, be patient.  Crash reports will be automatically reported back to us using . Bugs or feature requests should be reported here on meta and tagged . Please do not use the Google community to report bugs.  As always, we welcome your feedback and are committed to building the best mobile app possible for browsing the Stack Exchange sites.


How can I reset the background images I LIKE for windows 10

Before you point me to the countless answers of how to change backgrounds, here is the above question in DETAIL.   In Windows 10, every morning it comes up with a new photo background asking me if I like the background. If I respond on the upper right part of the screen with a YES, Windows 10 records that I like it and it becomes one of the images in my backgrounds collection and is used in rotation with other images I like.  There were a few images I accidentally said yes to when I meant to say no. Is there a way to reset this rotation to start over or maybe a way I can go back and remove that specific image from my selected images in the collection so that it will no longer be in my collection of backgrounds?


Proof with induction that $n^2+n$ is even, when $n \in \mathbb{N}$

Problem  Proof with induction that $n^2+n$ is even when $n \in \mathbb{N}$  Attempt to solve  $n^2+n$ is even when it satisfies: $$ n^2+n \mod 2 = 0 $$ meaning it's divisible by 2. I can begin to proof that this statement holds when $n \in \mathbb{N}$.  Base case  the statement holds when $n=0$  $$ 0^2+0 \mod 2 = 0 $$  Which is true since $0$ divided any $n\in \mathbb{N}$ is $0$.  Inductive step  Assume statement holds when $n=k$ (induction hypothesis)  $$ k^2+ k \mod 2 = 0 $$  then let $n = k+1$  $$ (k+1)^2 + (k+1) \mod 2 = 0 $$ $$ \iff k^2+2k+1+k+1 \mod 2 = 0 $$ $$ \iff k^2+k + 2k + 2 \mod 2 = 0 $$  Based on induction hypothesis $k^2+k \mod 2 = 0$. Which implies we can deduce our statement to  $$ \implies 2k + 2 \mod 2 = 0 $$ Which is true for $\forall k \in \mathbb{N}$ since any $k\in \mathbb{N}$ multiplied by 2 is divisible by 2. Adding 2 to this does not alter the divisibility since 2 is also divisible by 2.   Q.E.D    Is my proof correct?


Does the lie algebra know which lie group elements will commute?

If we have elements in the lie algebra $a, b \in \mathfrak{g}$, when is it true that $\exp(a) \exp(b) = \exp(b) \exp(a)$? Naively, I believe that if $a$ and $b$ are linearly independent, then their exponentials can commute. I'm not sure how to prove this, however. In the case of matrix groups, I believe the correct condition is that when $a$ and $b$ commute, then we have that $\exp(a) \exp(b) = \exp(b) \exp(a)$, since the matrices $a, b$ will behave just like real numbers. But this "feels wrong", since I am invoking the multiplicative structure of $a$ and $b$. But as elements of the lie algebra, all I have is the vector space structure! I suppose the way to correct this is to use the lie bracket structure, and state that if $[a, b] = 0$, then the exponentials commute? I am still looking for a proof, though. I know a "nuke proof" that . If $[X, Y] = 0$, then we can solve for $\exp(a) \exp(b) = exp(z)$, where: $$ z = a + b + \frac{1}{2}[a, b] + \dots \text{expressions involving }[X, Y] \\ z = a + b + 0 = a + b $$ So this gives me $\exp(a) \exp(b) = \exp(a + b) = \exp(b + a) = \exp(b) \exp(a)$. But this is way too much firepower to prove something that feels elementary; BCH is complicated. What is a simple proof of the above fact?


A simple permutation question - discrete math

There are five distinct computer science books, three distinct mathematics books, and two distinct art books. In how many ways can these books be arranged on a shelf if one of the art books is on the left of all computer science book, and the other art book is on the right of all the computer science books?     For my answer I was thinking since there are $10$ books total and $5$ are computer science books, then I could place an art book on the first, second, third, fourth slot ... but I do not know how to finish it, I am sure it has something to do with rule of sum. Any advice appreciated. Thank you.


When Animal Companion is multi-classed, does Command come with it?

In my ongoing campaign of Dungeon World, a Bard chose to multi-class a skill, Animal Companion from the Ranger class. (Now, I suspect the bulk of my question depends upon a misunderstanding of how to handle such a companion, but let's leave that for another question.) This skill, Animal Companion, seems pretty tightly coupled with Command. When this Bard chose Animal Companion, should she have gained Command as well? Or is she limited to non-Command-based use of her new Raven companion?  This confusion is related to learning a Cleric spell as a multi-class move and then getting (or not getting?) the ability to Commune to re-memorize it daily.


First column of join attributes by location on QGIS

I am trying to join attributes by location using processing (I have many so I need to do them by batch)   processing.runalg('qgis:joinattributesbylocation', firstlayer, secondlayer,u'equals',0,0,'',1,layerOutput)   The first future are integers then the outputs became all negative numbers. i.e. 4120034510 becomes -174932786  Could some one help me how to avoid this?  ( may be an easiest way to change first column to string , or better ideas)


A question from "The meaning of the relativity, by A.Einstein" - Lorentz transformations

Let $K$ and $\bar K$ be two cartesian co-orditate systems in $\mathbb{R}^3$. The element: $$s^2=(\Delta x^1)^2+(\Delta x^2)^2+(\Delta x^3)^2$$ is an invariant in all co-ordinate system. I want prove that the relations between de co-ordinates of $K$ and $K$ must be linear.  In the book: "The meaning of relativity, by A. Einstein" we can find the following reasoning:  Suppose that $\bar x^\nu=\bar x^\nu(x^1,x^2,x^3)$ and note that: $$\left\{\begin{array}{lll} (\Delta x^1)^2+(\Delta x^2)^2+(\Delta x^3)^2= \text{const.}&(1)\\ (\Delta \bar x^1)^2+(\Delta \bar x^2)^2+(\Delta \bar x^3)^2 = \text{const.}&(2) \end{array}\right.$$ Also by Taylor's theorem: $$\Delta \bar x^\nu = \sum_\alpha \frac{\partial \bar x^\nu}{\partial x^\alpha}\Delta x^\alpha+\frac{1}{2}\sum_{\alpha,\beta} \frac{\partial^2\bar x^\nu}{\partial x^\alpha\partial x^\beta}\Delta x^\alpha\Delta x^\beta+\ldots\qquad (3)$$ Substituting $\Delta x^\nu$ given by $(2)$ to $(3)$ and compare this with $(*)$ then we deduce that $\bar x^\nu=\bar x^\nu(x^1,x^2,x^3,x^4)$ must be linear.  Can anybody help me to take $\Delta x^\nu$ given by $(2)$ and put into $(3)$ to deduce that the transformation must be linear?


A normal divided by the $\sqrt{\chi^2(s)/s}$ gives you a t-distribution -- proof

let $Z \sim N(0,1)$ and $W \sim \chi^2(s)$.  If $Z$ and $W$ are independently distributed then the variable $Y = \frac{Z}{\sqrt{W/s}}$ follows a $t$ distribution with degrees of freedom $s$.  I am looking for a proof of this fact, a reference is good enough if you do not want to write down the complete argument.


How do I select questions with a particular combination of tags?

I need to select questions with only particular tags. I need help to select questions which have SQL along with SQL Server and SQL Server 2008. Questions that have any other tags must not be selected. I saw , but I also get questions that have a phpadmin, C#, etc. I am confused. How do I do it?  is URL for my filter.


macOS: Is there a way to show an image constantly on screen (like a watermark)?

I'm looking for a very simple way to add a watermark to my screen which should be shown whatever I'm doing, is it during a Zoom call, or is it when giving a presentation, or similar (I don't necessarily need it to show during fullscreen mode). The reason is that I want to record my screen using QuickTime Player, and the watermark should be on the video. I know that there are many post-production tools that offer adding watermarks, but I don't want to do any post-production, I want to have everything on screen while recording already. (I also know that there are screen recorders which offer placing a watermark to the end result. I'd rather also avoid using another screen recording software, but if I don't find any other way to do it, then I'm open to a simple, non-pricy alternative to QuickTime Player.)


How do I resize/change resolution of pictures easily?

I just tried to make a post on another StackExchange site, but unfortunately, when I tried to take a picture of the problem, I got an error that the image must be less than 2 MB to upload it to StackExchange! The edit button on my Android photos app lets me draw over, crop, change tint/brightness/contrast, and add lots of WACKY EFFECTS to my pictures, but I can't figure out how to shrink the resolution! Thanks in advance.


Why making new Greeting() as Greeting is an interface in lambdas expression?

Greeter.java  package lambda; import java.util.stream.*;  public class Greeter {      public static void main(String[] args) {         // TODO Auto-generated method stub         Greeting Greet1 = () -> System.out.println("Hello gretting..");          Greeting innerclass = new Greeting() {             //why new Greeting is an interface ?             public void perform(){                 System.out.println("Hello inner greeting");             }         };         Greet1.perform();         innerclass.perform();     } }   Greeting.java  package lambda;  public interface Greeting {      public void perform();  }      OUTPUT   Hello gretting..  Hello inner greeting...  why this line is working?  Greeting innerclass = new Greeting() {