There is custom message that comes each time I ssh or scp which I would like to hide. I still want the rest of the stderr to go to stderr output.  For example: a.sh contain one line: ssh example.com "touch /tmp/a.log ; echo ok"  myuser@host $ ./a.sh No valid ciphers for protocol version 2 given, using defaults. ####### # this is prod # ####### ok myuser@host $   So I want to hide the first 5 lines, or if putting it into scripting grep -v -E "#|No valid ciphers for protocol". Any other error should still be output to screen/stderr.


Roman numerals not close enough together

Instead of 'III' (three 'I's), I want the numbers to look more like those in the attached image.  When using Computer Modern font, is it possible to just remove the horizontal space between letters?  a previous post worked around this by defining a new command using /makebox, but some of the dimensions used absolute length units and therefore is not a solution for different fonts, especially when you want to use this in subscripts or superscripts.


I'm trying to prove that $\operatorname{lcm}(n,m) = nm/\gcd(n,m)$ I showed that both $n,m$ divides $nm/\gcd(n,m)$  but I can't prove that it is the smallest number.  Any help will be appreciated.


Is there gravitational black hole radiation?

Black holes have entropy and temperature. As Bekenstein and Hawking showed, this yields the emission of electromagnetic radiation in the form of photons: black holes radiate photons.   The next question is straightforward: do black holes also radiate gravitons? Given that the answer is yes, as the literature shows, what determines the ratio between photon and graviton emission?  -  P.S. The question is not about how gravity gets out of a black hole. This is answered in many places. The question is: is there a slow evaporation process of black holes also via gravitons, in addition to the evaporation via photons.  P.P.S. I am not asking about the radiation of massive particles. Only about photons vs. gravitons.


Disclaimer  Please, if you don't like self-answers just avoid this thread. (For more details see: )  Context  Given a measure space $\Omega$ with sigma-finite measure $\lambda$.  Consider a finite measure $\kappa<\infty$.  Then there exists a decomposition: $$\kappa=\kappa_{ac}+\kappa_s\quad(\kappa_{ac}\ll\lambda,\kappa_s\perp\lambda)$$  Moreover the singular measure splits into: $$\kappa_s=\kappa_{sc}+\kappa_{pp}$$  Question  Is the last decomposition w.r.t. singletons or w.r.t. atoms? (See the wikipedia articles  and .)  Moreover, can it make a really important difference? (I guess so but cannot imagine what...)  Remark  The absolutely continuous measures are characterized precisely by the measurable functions: $$\kappa_{ac}(E)=\int_Ehd\lambda\quad(h\geq0)$$


Looking for the title of a gold heist movie involving the telekinetic son of an extraterrestrial/alien?

Some 30 years back, I saw a film about the son of an extraterrestrial who gets involved in a gold heist.  The main character does not initially know that he is the son of an extraterrestrial and that has special telekinetic powers. The film opens, I think, with him being in some train yard, his foot getting stuck in a switch with a locomotive approaching. He stops it using his powers intuitively, possibly passing out (not realizing what he actually did). I think his mother subsequently reveals his heritage to him.  He somehow gets hired as a bodyguard for someone planning a gold heist. I think they know his abilities and use him to steal a million US dollars. Actually, that is just a distraction, covering that they steal 30 million dollars from the same location (through the air, not sure on that part).  The last part I remember is some underground tunnels where the thieves set up to melt the gold. The main character is locked in there.  Does anyone know the title of this movie? Searching for things like "sci-fi gold heist extraterrestrial etc." did not reveal anything to me. I also had a hard time picking proper tags (sorry).


How to access the Keyboard Layout Options in 13.10+

In 13.04 or below I only needed to access the keyboard layout and then click on the Options button as seen in the image below:    In 13.10 the Options button is missing as seen in the following image:    So what is the new method to access any and all Keyboard Layout Options. In my case I wish to activate 3 of them, from killing X, to some custom keys.


Add a way to see where links go in Android app

I think it would be good to have a way for the user to view the target URL of a link before following it. I'm pretty sure that I'm not the only one who dislikes blind-clicking -tapping links.   When I use SE in the mobile browser, I routinely long-press links to find out where they go before following them. I wish I could do the same thing in the app, with the same or a similar method.  (It's important that this won't conflict with text selection, since you can't long-press on links to select them now anyway.)


Why didn't I recieve the "Good Answer" badge?

I gave an answer and got a score of more than 40 but still have not got silver badge called "Good Answer". Will it take time to get it? I have read somewhere that some jobs are run after certain interval but I have still not received the badge.   Here is the screenshot where you can see that I got 65 points.


For about 2 weeks, multiple people (around 10 that I know of) in our company are having trouble accessing Stack Overflow; independently of the browser, and on Linux as well as Windows. The symptom is that assets loaded from cdn.sstatic.net keep waiting forever or until they time out.   On my machine the status is that at some point those requests time out and a version of the page without any images or CSS appears.  For some Windows users reboots help, for others it doesn't.   Meta Stack Overflow (now Meta Stack Exchange) always loaded for me.  A workaround for my machine was to disable IPv6 temporarily on Linux with the command echo 1 | sudo tee /proc/sys/net/ipv6/conf/all/disable_ipv6.  Note that no other site (that I visit) has been affected like this.  Update 2013-08-12: our network guy did some checking and insists the problem lies with Cloudflare. We seem to have issues when trying to connect to them with IPv6. We can't go around and disable our IPv6 Support since we need it for our internal infrastructure. We employ the following workaround (sadly only works with Firefox):   Go to about:config find the configuration key called network.dns.ipv4OnlyDomains Set it to the following list of domains (or add them if you already have something in this key): cdn.sstatic.net,www.cloudflare.net,cdn-careers.sstatic.net


What's the difference between 12.04 and 12.10?

I have an Asus K55V and I'm wondering which version of Ubuntu I should be attempting to use. The website offers 12.04 (LTS) and 12.10.


Is there a word to describe a highly desirable cursed treasure?

Is there a single word to describe an object or idea that is so desirable that everyone wants to attain it but once they have it they are immediately cursed?  The idea is often used in literature—some examples:   In Lord of the Rings, the 'one ring' is a perfect example of this. In Guy de Maupassant's story , the necklace might be considered to be this. There are many stories of people making deals with the devil (see question: ), or being granted three wishes by a Djinn or fairy, which inevitably turn out bad. In the Twilight Zone episode , Bemis's desire to be left alone with his books would be an example of this word.   'Bane' covers the cursed part, but no one desires it.  Is there a single word to describe a most highly desired treasure that (knowingly or unknowingly) comes with a curse?


Search for question with exclusively certain tags

How do I search for questions that only have certain tags. For example:  If I search [python] the search will come up with any questions that have python as one their tags. This search would show something tagged java,python  How do I search for questions that have only the tag python and no other tags?


I cannot see my uploaded image in stackoverflow

This is the topic that I posted . I uploaded a image, but it didn't display. Is it the website problem?


I am trying to sum the following series, given n is a positive integer, $$ n+n(n-1)+n(n-1)(n-2)+...+n! $$ I think there is a solution, but if not, an approximate result will also be appreciated.   Regards.


Common Doubt:Why there is the difference in the answer? In chessboard 2 squares are selected...

If two of the 64 squares are slected at random on a chessboard, the probability that they have a side common is..... .   Attempt  Choosing the corner side and the required square is ${{4_{C_1}}*{2_{C_1}}}$  Choosing 4 corner sides remaing squares and the other required square is ${{24_{C_1}}*3}$  And other remaing squares ${36*4}$  And the total selection is ${64_{C_2}}$  But the probability is $\frac{1}{18}$ and I am getting $\frac{1}{9}$. Why?  I have seen the same question on math stack exchange but was not able to connect to it. Also they don't answer the question that why my method has not been able to given the correct answer.  the answer given there by the user Jack  just states for numerator and says to divide it rather than explaining why to do it.  Thanks for the help.


I receive emails but I get account error and cannot send.  Any idea what can be the problem?


What font (with math support) is this (picture)?

I've seen this font several times (in Springer books for instance) and would like to use it in my documents if possible. I've tried What The Font to no avail. Can anyone give me some pointers on what it is and how to use it with pdfLaTeX?    (picture taken from )


Solving the equation $x^2=2^x$ algebraically.  I solved it graphically, however, upon solving this equation algebraically, I realized that I was not equipt with the necessary tools to solve it. I was not able to reduce it to anything solvable within the scope of my knowledge.


Tom believes that that tree bears fruit.  What is it called when two "that's" are used in a row when only one is needed?


How to tell Photoshop to treat layer as a Vector graphic?

I have a 48*48 png file that I'm trying to scale up. Even though I converted it to a Smart Object, when I scale it up, Photoshop mixes the color of adjacent pixels to make more pixels for the transformed sized which is not what I want.  Here's a screenshot of the image:   When I'm scaling it, the preview does not show mixed colors:   But when I hit enter, Photoshop mixes the colors:   Which as you can see looks very blurry. How can I achieve the the second photo?  Basically I want to tell Photoshop to treat the layer as a Vector and not an Image.  Here's the original png file if you want to download:


best way to copy your ubuntu to a new hard drive

I found this question  to be close to what I need, but I wonder if it is still going to work if, instead of two different machines, I want to clone all to a new hard drive, bigger, and of a different brand (installed on the same machine).   The other option that I was considering is to the do a back-up of the current system and restore it (after a fresh install of the same ubuntu 12.04) on the other hard drive, what do you think?  I am using ubuntu 12.04.5 LTS


Getting Started - Community Cloud Package Installation

Can Salesforce AppExchange package be installed on Salesforce Community Cloud?


I am trying to prove that     $C+C =[0,2]$ ,where $C$ is the Cantor set.   My attempt:  If $x\in C,$  then  $x= \sum_{n=1}^{\infty}\frac{a_n}{3^n}$ where $a_n=0,2$  so any element of $C+C  $ is of the form  $$\sum_{n=1}^{\infty}\frac{a_n}{3^n} +\sum_{n=1}^{\infty}\frac{b_n}{3^n}= \sum_{n=1}^{\infty}\frac{a_n+b_n}{3^n}=2\sum_{n=1}^{\infty}\frac{(a_n+b_n)/2}{3^n}=2\sum_{n=1}^{\infty}\frac{x_n}{3^n}$$  where $x_n=0,1,2, \ \forall n\geq 1$.   Is this correct?


Let $R$ be a PID, and $r\in R- \{0\}$. Prove that   $\langle r\rangle$  maximal $\iff r$ irreducible.   "$\Leftarrow$"Easy.  "$\Rightarrow$"If $J=\langle r \rangle$ then we will prove that $r$ is irreducible. If $r=ab$, we want to prove that $a\in U(R)$ or $b \in U(R)$.  If we take the ideal which is generated by $\langle a\rangle$ then (because $J$ is maximal)$$\langle a\rangle \subseteq\langle r \rangle \iff r\mid a \iff a=kr, k\in R \Longrightarrow r=krb\iff r(1-kb)=0_R \iff kb=1_R$$ so $b\in U(R)$. Same way if we work with $\langle b \rangle$.  Is this proof right?


Reduce site misuse by new users - mandate getting the Informed badge (taking tour)

Proposal  All new sign-ups* should be required to obtain the Informed badge, which simply means taking the tour, before they are allowed to post their first question or answer.  * During the feature launch transition period, this could include all existing profiles with <100 points.  Rationale  I think if new sign-ups take a moment to go through the tour and have a basic understanding of how the site functions, it will greatly reduce the amount of uninformed misuse we get from the new signups. Some of these include:   Treating the site like a forum (posting their follow-ups as answers) Not taking some time to phrase and format their questions properly (esp doing code dump) Not upvoting or using the green checkmark. Wrongfully downvoting answers that are attempting to help asker, but are not quite there yet (yes, this actually happened!) (This requires some rep, so not applicable.) Not tagging properly (just putting one tag because user is forced to). Asking questions that shouldn't be asked in the site. Not being aware of the ability to edit questions or answers.   Edit:  Comparing  (a very short and visually interesting overview of the site) to an  (a long, boring, full-text legal document) is not a fair comparison.  People who aren't going to bother to read, still won't. But people who will read, would only need to be encouraged to read and they will. (Mandating something is also a form of encouragement; severe I admit, but effective.)  About it being a barrier, it's a rather easy barrier to cross, and anyone who can get along just fine without it, can also get along just fine crossing it easily.  I don't propose this to be a one-size-fits-all solution, but at least it could help reduce some of the problems. We can't be searching for that ONE solution that will solve ALL problems on the site, but rather solve each problem with a unique solution tailored to it. We have to let all the solutions work together in solving all the problems plaguing the site.  So this is proposed as a solution to take care of a few problems in the site, not everything.


How to calculate shot angle and velocity to hit a moving target?

I am developing a 2D Android game and I am making an aiming algorithm for AI projectiles to hit enemies either following a path, or free moving. At the moment it just calculates where the target will be after a distance and fires a projectile to meet it at that distance. Of course this means varying the projectile speed to meet the target.  Does anyone have any tips for a simple-ish algorithm (optimal-ish) to calculate when the projectile needs to fire and where it needs to aim if it can only travel at a constant velocity? Say the projectile goes twice the speed of the target?  The only way I can think of involves searching and seems quite large.


Reward finding duplicate questions - +10, +2, -5

deals with various ways of rewarding the finding of duplicates, a tough and increasingly necessary janitorial task.  Here's a concrete suggestion:   Reward the finder of a duplicate with +10 points if the question gets closed as a dupe. If multiple duplicates are found, reward all finders whose suggestion was voted for at least once by another user. (The limitation is to avoid gaming by making frivolous suggestions when it's obvious that a question is going to get closed as a duplicate.) Reward each following closevoter who picks one of the previously suggested dupes with +2 points if the question gets closed. Punish everyone involved (dupe-finders and dupe-voters) with -5 points, and revoke all rep gained from the dupe-voting, if a question closed as duplicate gets reopened.   A punishment for mis-voting is going to be controversial but in my eyes, it is absolutely essential. Finding a good dupe is a work of love: You need to make sure you understand the OP's question, and you need to scan every potential duplicate for whether it really contains an answer that will help the OP. Everyone dupe-votes carelessly from time to time, so the threat of punishment needs to be present to keep everyone on their toes, just as the threat of downvoting does when you post an answer.  If you think +10 is too high a reward: Consider that finding a duplicate can often be more work than writing an answer, and a correct answer usually nets you at least 10 points, if not much more.   If you think -5 is too much of a punishment: -2 might work as well, although I really think there should be a harsh punishment on an unfair dupe-closing.


How to make a Plane object on a 3D character always face the camera

rn im working on a retro N64/PSX/Dreamcast 3D character model for my fan JJBA Stand ability and I wanted to use a technique where plane objects always face the camera like the bob-ombs on SM64, does anyone knows how to achieve this?


Joint density invariant under orthogonal transformations

I have a problem and I am totally stuck!  I have to show that when the distribution of two random variables $X$ & $Y$ given by $g(x,y)=f(x)f(y)$ is invariant to orthogonal transformations, then it holds that $$f(x)f(y)=f(0)f\left(\sqrt{x^2+y^2}\right).$$   Any ideas on how to approach this? I have found that when the random variables are transformed by an orthogonal matrix like this $\scriptstyle \begin{bmatrix}\tilde{X}\\\tilde{Y}\end{bmatrix}=\begin{bmatrix}a&b\\c&d\end{bmatrix}\times \begin{bmatrix}X\\Y\end{bmatrix}$, then the distribution of $(\tilde{X},\tilde{Y})$ is given by $\tilde{g}(x,y)=f\left(\frac{dx-by}{ad-bc}\right)f\left(\frac{ay-cx}{ad-bc}\right)$, and my thought was that maybe it could be proven that $f\left(\frac{dx-by}{ad-bc}\right)f\left(\frac{ay-cx}{ad-bc}\right)=f(0)f\left(\sqrt{\scriptstyle\left(\frac{dx-by}{ad-bc}\right)^2+\left(\frac{ay-cx}{ad-bc}\right)^2}\right)$, but it doesn't get me anywhere.


Can you get a playground to swing from stationary

I feel this might be a FAQ but I would love a definitive answer.  Imagine a frictionless stationary idealised child's playground swing.  If you are sitting on the seat of the swing, is it possible in principle to set it into motion by simply moving your body and pulling on the chains of the swing? If so, is there a simple explanation for how you can change your center of mass without an external force acting on you?


Print updating variable in the same line

What I'm trying to code is pretty simple:  I want to print an iteration variable, but I don't want all the lines printed for each loop, I want that will update the previous one.  Example:  for i in range(0,2000):    print 'number is %d', %i    Wrong result:  number is 0 number is 1 number is 2 number is 3 number is 4 number is 5 number is 6 ... ...   What I want is:  number is 0    At the second iteration:  number is 1 `(it will replace 0 and I don't want the previous 0 anymore).`   It will be something like updating percentage of something in only one line.  Does a function exist for it in Python?


How do I retain the quality of text in a GIMP png uploaded to Facebook?

I used Gimp to create a quote image and I uploaded it to Facebook. I made sure to only use web-safe colors, and the fonts I'm using are Impact Condensed and Arial. However, the uploaded image drastically loses quality and the fonts aren't sharp/surrounded by a fog/are blurry:  Before uploading:   After uploading:   If you open the images in a new tab, you can see the difference between the two clearly.    I tried enabling/disabling Interlacing (Adam7) and the other export settings, but I haven't been able to make a difference. All help appreciated.


I have a 20cm hole in a wallpapered wall. Can I get away with filling the wall with plaster, then painting over it, without stripping the wallpaper off the entire wall first? Or must I strip the wallpaper first?


bc: Why does `ibase=16; obase=10; FF` returns FF and not 255?

I've been using bc to convert numbers between binary to hex, octal to decimal and others.  In the following example, I was trying to convert base 16 (hex) number to binary, octal and decimal.  I don't have any problem with the first 2 attempts.  $ echo 'ibase=16; obase=2; FF' | bc   11111111 $ echo 'ibase=16; obase=8; FF' | bc  377   But when I tried to convert base 16 (hex) number to base 10 (decimal), I was getting wrong answer. The answer should be 255  $ echo 'ibase=16; obase=10; FF' | bc  FF


Why do calculated lists behave different than written lists

I have following code:  # python 3.8    normtable = [[None, None],[None, None],[None, None]] calctable = [[None]*2]*3 print('Before update - Normaltable: \t\t'+ str(normtable)) print('Before update - Calculatedtable: \t'+ str(calctable)) normtable[0][0] = 'hello' calctable[0][0] = 'hello' print('After update - Normaltable: \t\t'+ str(normtable)) print('After update - Calculatedtable: \t'+ str(calctable))   Output is like this:  Before update - Normaltable:        [[None, None], [None, None], [None, None]] Before update - Calculatedtable:    [[None, None], [None, None], [None, None]] After update - Normaltable:         [['hello', None], [None, None], [None, None]] After update - Calculatedtable:     [['hello', None], ['hello', None], ['hello', None]]   Why does the calculated list behave differently? I understand that lists are mutable and thus if the same list is used in another list and the second list edited the first one is also edited as both point to the same values. This explains, why that after multiplying the same list with factor 3 all three lists will always contain the same information. But then why would the *2 not do the same and as a result all strings change to 'hello' and not just the first ones? What would be an alternative way to have this list set up with a variable size?  Thanks in advance, best answer will be marked.


Formula for the sum $\sum_{k=0}^a \frac{x^k}{k!}$

How does one find a formula for the sum $\sum_{k=0}^a \frac{x^k}{k!}$ ? According to the post mentioned in the comments: $$\sum_{k=0}^n \frac{x^k}{k!}=\frac{ \Gamma (n+1,x)}{n!}e^x$$ ...but how do you actually evaluate $\Gamma (n+1,x)$ for the positive integer n?


Prove that the family of open sets in $\mathbb{R}$ has cardinality equal to $2^{\aleph_0}$

Let $\mathcal{T}$ be the family of all open sets in $\mathbb{R}$. Show that $| \mathcal{T}|=2^{\aleph_0}$  $\textbf{My Attempt:}$   I know that $\forall A \in \mathcal{T}$. $A$ is the countable union of open intervals with rational end points.   I want to use the Cantor-Bernstein Theorem. That is I need to find injective functions $f$ and $g$ such that $f: 2^{\aleph_0} \to \mathcal{T}$ and $g: \mathcal{T} \to 2^{\aleph_0}$.  I know each $A \in \mathcal{T}$ is of the form $A = \bigcup_{x \in A} (r_x,s_x)$ where $r_x,s_x \in \mathbb{Q}$. How can I use this fact to find the injective function $f$ and $g$?


A simple proof that a polygon circumscribing a circle overestimates its perimeter

Looking at the picture below, it's easy to see why the perimeter of a polygon inscribed in a circle is an underestimation of the circle's perimeter. This follows from the triangle inequality: Any side (say $AB$) of the polygon is shorter than the circular arc with the same endpoints ($\stackrel{\frown}{AB}$). Summing all these inequalities shows the perimeter of the inscribed polygon is indeed smaller than that of the circle.  I'm wondering if there is proof that the perimeter of a circumscribed polygon always overestimates the perimeter of the circle, which is as simple as that of the inscribed polygon case. Thanks!


GNU parallel vs & (I mean background) vs xargs -P

I'm confused about the difference or advantage (if any) of running a set of tasks in a .sh script using GNU parallel  E.g. 's answer:  parallel ./pngout -s0 {} R{} ::: *.png   rather than say looping through them putting them in the background &.  E.g. 's answer:  #copied from the link for illustration for stuff in things do ( something   with   stuff ) & done wait # for all the something with stuff   In short are they just syntactically or practically different? And if practically different when should I use each?


How to prevent: `CIFS: Unknown mount option "defaults"`?

Context: I want to enable a normal user to mount a certain cifs mount on his system (Debian Strech). I therefore added the following entry in /etc/fstab (note the added ,user in the options):  //server/share/ /home/user/mountpoint cifs defaults,user,uid=user,credentials=/home/user/.cifs-creds 0 0   Also the credential-file is owned by the user and is readable/writable/executable (700).  Subsequently mounting as root works (i.e. cifs-utils are available on the system, the credential-file exists and is correctly populated)! But mounting as a user does not, resulting in the following output:  user@system: ~$ mount mountpoint mount error(22): Invalid argument Refer to the mount.cifs(8) manual page (e.g. man mount.cifs)   /var/log/kern.log states:  Jun  4 11:36:52 system kernel: [173283.233509] CIFS: Unknown mount option "defaults"   So, somehow, when executed as a user, the defaults option can not be used to mount? When the ,defaults option is removed from the fstab entry, users can mount (without error) but that would leave out a lot defaults (and using the defaults (other than: ,user) should be possible right?).  Hence my question:   What is the advised fstab entry to have users mount a CIFS/SAMBA share to prevent the mount error(22): Invalid argument caused by the CIFS: Unknown mount option "defaults"?   Should I simply leave out ,defaults or is there another method to do this (I tried Googling on this, but every tutorial / explanation I find seems to confirm the method used)?


newbie here.  As I read through webpages, i got to know that Oscillators are capable of changing DC to AC. I made a phase shift circuit in Multisim, but I got no idea what should I do next.  I was thinking using DC source as input and it will produce AC output, like some sinusoidal graphs. But if use AC Sweep, DC definitely will be open.  Any idea? Thanks!


ArcGIS Dissolve failing with small polygons

I have an arcpy script which clips (Clip_analysis) a shapefile of polygons to a grid square, converts any multipart polygons created to singlepart polygons (MultipartToSinglepart_management), runs dissolve (Dissolve_management) and then gets the area of the dissolved polygon to get the proportion of the grid square that is covered by polygons.  In the arcpy, the clipping is done using a 400m x 400m rectangular arcpy.Polygon, created from a point array.  When replicated in arcGIS desktop, I used a polygon shapefile with one feature (the same rectangle as used in the arcpy).  This script has been run many times without issue, but now I get an error in a particular (400m x 400m) grid square:  Error 999999: Error executing function. Invalid Topology [Y coord limit exceeded.] Failed to execute (Dissolve)  I can replicate the error using shapefiles/geodatabases and ArcGIS tools (10.1).  The grid square is nowhere near the extents of the coordinate system (the grid square is in London and the Coordinate system is British National Grid (EPSG: 27700)), and the grid squares North, East, South and West of that square all work fine.  The grid square only contains two small triangles from the same original polygon, and neither extend further than 75cm from the base of the grid square.  If I manually edit the polygon to extend over 1m from the base of the grid square, dissolve works fine.    I've tried repairing the geometry, but that didn't help.  I have tried various XY Resolutions and Tolerances (including not set, 1cm and 1m) with no success  What could be causing this error?  Is there a work-around?    When I run using the tool dialog, I get the same error, so it looks like a Dissolve tool or data problem, rather than a python problem.


Construction of choice function using powerset axiom: Where am I going wrong?

Assume we have a non-empty  $X \equiv \{ A_i \}_{i \in I}$. Then the  asserts that there exists a choice function $F: X \rightarrow \cup X$ such that $F(A_i) \in A_i$. I claim that it is possible to build the choice function using just the . Of course this cannot be true because choice is independent of $ZF$. So where am I going wrong? Constructing the choice function $F$ using $X \equiv \{ A_i \}_{i \in I}$ and powerset axiom  Given an indexed family of sets $X \equiv \{ A_i \}_{i \in I}$, first make this family unique, by creating a new collection of elements $Y \equiv \cup_{i \in I}\{i\} \times A_i$. This  Build the powerset $P = 2^Y$.  Filter subsets of the powerset that have a single element $(i, \text{some element in }A_i)$ for each $i \in I$. Formally, create the set:   \begin{align*} &\operatorname{ChoiceFns} \equiv \{ p \in P : \forall i \in I, \text{there exists a unique $a$ such that $(i, a) \in p$}\} \\ &\operatorname{ChoiceFns} \equiv \{ p \in P : \forall i \in I, (\exists a \in A_i, ((i, a) \in p) \land (\lnot \exists a' \in A_i, a' \neq a \land (i, a') \in p))  \} \end{align*} This now gives us a collection of choice functions, since each element $p \in P$ maps  the index $i \in I$ to a unique element $a \in p$? What am I missing?  How am I able to build a set of choice functions ?


I am having some trouble getting break to work in a while-loop. I have created a function main() which contains three input() regarding global scopes, these three comes directly after each other. I want the program to end immediately if you enter an incorrect value into one of these ìnput() and tried to accomplish that with breakwithout success. So the question is why can't I use break in my while-loop? Allowed values in my global scopes: Scenario 1 or 2 games should be greater than zero board_size 3, 5 or 7 def main():          while True:             board_size = int(input("How big playing surface (3/5/7)? "))                  if board_size != 3 or board_size != 5 or board_size != 7:             break              while True:         games = int(input("How many games do you want to simulate? "))          if games <1:             break      while True:         scenario = int(input('What scenario (1/2)? '))          if scenario != 1 or scenario != 2:             break      print_stats(games, scenario, board_size)


I've created a large database on my local WAMP webserver.   I would like to send that database with all tables and table data to another computer.   Is this possible?    mySQL ver: 5.5.15 PHP ver: 5.3.8 Apache ver: 2.2.21   Thanks


How do you print the code of a shell function in terminal?

I am using zsh and I have defined few utility shell function in some shell scripts, few of them called from ~/.zshrc, so let's assume that we don't know the location of these functions. One function is:  function k.pstree.n {     if [ "$1" != "" ]     then         pstree -p | grep -C3 "$1"     else         printf "  Please specify the name of the process you want to show!\n"     fi }   How can I print the code of that shell function?  I can think of a search & grep like:  find $(pwd) -name "*sh*" -type f -printf "\"%p\"\n" | xargs grep -C5 "k.pstree.n"   but this assumes that I roughly know the location which is not true here.


Permission denied while running make install

I am trying to install gtk-server. First I typed the command ./configure and then make, but when I typed command make install it gave me this error:  osama@osama-HP-Compaq-6910p:~/Downloads/gtk-server-2.3.1-sr$ make install /usr/bin/install: cannot create regular file `/usr/local/bin/gtk-server': Permission denied mkdir -p /usr/local/bin /usr/bin/install -c gtk-server /usr/local/bin /usr/bin/install -c stop-gtk-server /usr/local/bin /usr/bin/install: cannot create regular file `/usr/local/bin/stop-gtk-server': Permission denied make: *** [install] Error 1


My profile page used to have a votes tab that showed me what my latest X votes were. It is not there anymore. What happened to it? Why was it removed? I looked everywhere but couldn't find anyone talking about it. I use this often to go back to downvotes and see if they've been edited to fix a problem so I can then remove my downvote.  Edit: I made this a feature request to bring this functionality back.


The parameter panel to modify primitives is greyed out

The black pencil lines show where I am talking about, the panel is translucent and does not allow any clicking? In the image I provided above I marked the area where now I cannot change the vertices of any new primitives I add in blender 2.79, everything else works but this area is now grayed out and doesn't do anything when clicked?


Geometric distribution with locks and keys

Assuming you have 8 keys - only one of them opens the lock. You try one by one without knowing which is the right key. If the key does not open the lock - you remove it. You do this until you find the right key that opens the lock. What is the distribution of the number of your tries until (and including) the opening of the lock.  Geometric Uniform No answer is correct Binomial HyperGeometric  I think the answer is "No answer is correct" because all these distributions (not including HG) is when you don't change the number of keys each "cycle" - and here you do! (You remove the key if it does not open) so your $p$ changes... and HG - I don't see how it can help here... But my answer is wrong! It is not "No answer is correct" Why is that? Which is answer is correct? this goes against my intuition. Thanks!


Minecraft server connection timeout on Mac OS X version 10.6.8

I was trying to connect to a new server that i saw that other people are capable of connecting to but im unable to connect to it and it keeps saying "io.netty.channel.ConnectTimeoutException: connection timed out: (server IP)"   For some reason it's not letting me join and its said that on another server ive been playing on and said this on another server "java.net.ConnectException: Connection refused: /(server IP)  Ive tried methods for fixing problems for this but when i try terminal the commands dont work and the other 2 servers used to work for me but suddenly stopped working a few days ago.


bounded predictor variable modeling constraint

I have a model similar to below with a continuous outcome, continuous predictor and a categorical variable. the goal of this analysis is to make inferences on the group variable. The issue is that y is bounded by x in the form of y >= -x. When the model makes predictions you can see in the plot below that the predicted value is outside the possible range. See the last plot.   How can this be remedied? A custom loss function to penalize going beyond the bound and use gradient descent regression? Or is there some other way? Thank you.   x =   rep(seq(-10,10,1),each=5)  y =  rep(0,length(x) ) weights = sample( seq(1,1000,1) ,length(x)) groups = rep( letters[1:5], times =length(x)/5  )   ## the outcome y has the relationship y >= -x for(i in 1:length(x)){   y[i] = sample(  seq(-x[i],-x[i]+ ifelse(x[i]<0 ,                                            sample(seq(1,10,.1),1),                                           sample(seq(5,40,.1),1) ),1)                        ,1) }   dat =data.frame(x = x, y = y, weights = weights, group = groups) model = lm(dat = dat, y ~ x + group + group * x, weights = weights) dat$FIT= predict(model, dat, allow.new.levels = TRUE)  library(ggplot2) ggplot(data = dat, aes(x = x, y = y, color = group))+geom_point( aes(size = weights))+ geom_line(data = dat, aes(x = x, y = FIT, color = group))    #data for new predictions newdata = data.frame( x = seq(-100,100,1) ,                        group = rep("c", length( seq(-100,100,1) )),                       bound = -seq(-100,100,1)                       )  ## when pridicting new data the outcome y has the relationship y >= -x ## but the predicted vales are below the bound. See how red line is below blue to the left of zero new_preds  = predict(model, newdata, allow.new.levels = TRUE) ggplot(data = newdata, aes(x = x, y = new_preds, color = group))+geom_line()  +   geom_line(data = newdata, aes(x = x, y = bound, color = "green"))


Cardinality of Cartesian product of sets

I was unable to find a proof (let alone a short one) for the proposition that $$|A\times A| = |A|\text{ for any infinite set }A.$$  The function from right to left is trivial, but I cannot find one from left to right.  Would be happy for help.


Prove that for each $m \ge 3$ the following holds: $d_m=(m-1)(d_{m-1}+d_{m-2})$

Let us denote by $d_m$ the number of sequences $(a_1,a_2,…,a_m)$ such that $a_i \ne i$ for every integer $i \in \{1,2,…,m\}$ . Prove that for each $m \ge 3$ the following holds: $$d_m=(m-1)(d_{m-1}+d_{m-2})$$  Since the following formula $d(n)=n!(1-\frac{1}{1!}+\frac{1}{2!}-\frac{1}{3!}+\frac{1}{4!}- \cdots +(-1)^n\frac{1}{n!})$ is not what we have to prove and this is how to find the number of derangements for $n$ distinct objects, can I answer this question by substituting $d(n)$ for $d_m$, $d(n-1)$ for $d_{m-1}$ and $d(n-2)$ for $d_{m-2}$ and using algebra to show that they are equal? Do I need to use mathematical induction and also show that they are equal for $n+1$ or do I need to solve this problem a different way?


Prove $x \equiv a \pmod{p}$ and $x \equiv a \pmod{q}$ then $x \equiv a\pmod{pq}$ for $p\neq q$ distinct primes.  Where can I start with this proof? It looks similar to the Chinese Remainder Theorem, but that deals with two different a values.


How can I use the spotlight in blender to cast shadows such and the batman symbol, or other "cool" lighting effects. I went into the compositor and tried assigning it a material, but that didn't work.


Sufficient conditions for $x,Ax,A^2x,...,A^{n−1}x$ being linearly independent?

Suppose $x\in\mathbb{R}^n$ and $A\in\mathbb{R}^{n×n}$, and all entries in both of them are non-negative. Moreover, we have $$\mathbf 1^Tx = 1,$$ $$\mathbf 1^TA = \mathbf 1^T.$$ What is a sufficient condition for $$x,Ax,A^2x,...,A^{n−1}x$$ being linearly independent?


Why code is running else statement when if statement is true in java?

belowis the code where I'm entering string CIVIC . as it is palindrome and strings are matching but code still executing else statement. as can seen in below image. What kinda mistake i'm doing? import java.util.Scanner;  public class PalindromeString {     public static void main(String[] args){         Scanner input= new Scanner(System.in);         System.out.println("Enter the String : ");         String  car= input.nextLine();         System.out.println(car);         String newcar="";          for(int i=car.length()-1; i>=0; i--)         {             newcar=newcar + car.charAt(i);         }                           System.out.println("new car >> " +newcar);         if(car == newcar) {             System.out.println("String is Palindrome");         }         else {             System.out.println("Not A Plaindrome as  " + newcar + " != " + car);         }              } }


How can I avoid the nested for-loops in the following Code and using the map-function instead for example?  import numpy as np  A = np.array([[1,2,3],[4,5,6],[7,8,9],[10,11,12]]) n = len(A[0]) B = np.zeros((n,n))  for i in range(n):     for j in range(n):         B[j,i] = min(A[:,i]/A[:,j])


I don't know where to ask this question so I posted it here.  I see that in Ubuntu the sign for Gigabytes, Megabyte etc are used as GiB, MiB etc. So my question is: What is the reason for using i between GB.


College number theory problem - need a pointer!

$n$ divides $2^{2^n+1}+1$ $\implies n$ divides $2^{2^{2^n+1}+1}+1$?  There are two ways to try to prove this. One is above, the other is its de Morgan counterpart: $n$ doesn't divide $2^{2^{2^n+1}+1}+1 \implies$  $n$ doesn't divide $2^{2^n+1}+1$. Disproving it requires only one example of course.  Tried using $\gcd(2^a+1, 2^b+1) = 2^{\gcd(a, b)}+1$ (where $a$ and $b$ are odd positive integers), stuck on both ends. I figured out that if $n$ divides $2^n+1$ then n divides both $2^{2^n+1}+1$ and $2^{2^{2^n+1}+1}+1$ but this implication doesn't work backwards (e.g. $n=57$).  Would appreciate some help.


UK Visit Visa Refusal for attending a fully funded summit

I have been refused visitor visa for a fully funded trip on the following grounds:


A simple doubt in number theory problem.

I considered an even number $n\geq 10$, where it is divisible by some positive integer $k$.  Also, $k$ divides $\frac{n}{2}$. Then $n = kq\implies k\cdot\frac{q}{2} = \frac{n}{2}$.  Can we say that $q$ is even in this case? Can anyone help to get it theoretically? Thanks a lot for the help.   PS.   From the answer given by Bill, it does not satisfy if we take $n=18,k=3,j=9.$ Kindly help. Let me rectify where I am going wrong. Please help.  $\quad\ \ \ \ \ \ \ \ \ $ If $\,\rm\ J,K\mid N\,\ $  then $\rm\,\ \color{#c00}K\ {\LARGE \mid} {\Large  \frac{N}{\color{#0a0}J}}\! \iff\color{#0a0}J\ {\LARGE \mid} {\Large \frac{N}{\color{#c00}K}}\, $ [$\rm\!\!\iff\!\!  JK\mid N\,$]  This part is not satisfied.


convergence of $\sum_{n=1}^{\infty} \frac{a^n}{n!}$

How can i check convergence of $$\sum_{n=1}^{\infty} \frac{a^n}{n!}$$ ?  I tried some of the tests for checking if it's convergent , but it's does not work.


How can I check for Python version in a program that uses new language features?

If I have a Python script that requires at least a particular version of Python, what is the correct way to fail gracefully when an earlier version of Python is used to launch the script?  How do I get control early enough to issue an error message and exit?  For example, I have a program that uses the ternery operator (new in 2.5) and "with" blocks (new in 2.6).  I wrote a simple little interpreter-version checker routine which is the first thing the script would call ... except it doesn't get that far. Instead, the script fails during python compilation, before my routines are even called. Thus the user of the script sees some very obscure synax error tracebacks - which pretty much require an expert to deduce that it is simply the case of running the wrong version of Python.  I know how to check the version of Python. The issue is that some syntax is illegal in older versions of Python. Consider this program:  import sys if sys.version_info < (2, 4):     raise "must use python 2.5 or greater" else:     # syntax error in 2.4, ok in 2.5     x = 1 if True else 2     print x   When run under 2.4, I want this result  $ ~/bin/python2.4 tern.py  must use python 2.5 or greater   and not this result:  $ ~/bin/python2.4 tern.py    File "tern.py", line 5     x = 1 if True else 2            ^ SyntaxError: invalid syntax   (Channeling for a coworker.)


Why do computer circuits tend to have so many resistors and capacitors?

As someone who has a decent understanding of computer architecture (but not of electrical engineering) I've always wondered why computer circuits tend to have so many resistors, capacitors, and other small circuit elements. Computing logic is binary - either wires have electricity going through them or they don't. So why the need to store/reduce the flow of electrons in so many different places? I'm guessing it has something to do with delivering voltage to different circuit elements from the power supply, or maybe controlling the rapid oscillation of the CPU clock, but I'm not sure.


Run .bashrc commands without opening a terminal

I have been editing my .bashrc file to run some commands, such as appending directories to the PATH variable. However, from my knowledge, .bashrc is only executed when a terminal is opened. (Correct...?) In this case, in order to make the necessary changes to PATH, I would need to open up a terminal each time I log on to Ubuntu.  This doesn't seem like a very elegant thing to have to do, particularly for people who tend not to use the terminal much. Is there a way to run these commands when Ubuntu boots up, without requiring a terminal to be opened?


In Python for *nix, does time.sleep() block the thread or the process?


Getting point attribute from polygon layer using QGIS?

I have two layers, one (A) has point features and the other (B) has polygons.  How do I produce a new table with some (the ID) or all the fields from the A table and some (the area code) or all from the B table where the B polygon contains the A point?  I am using QGIS.


I was trying to reinstall windows but on the step "Choose a Physical Location to Install Windows On" I stumbled upon this MSR partition I knew nothing about. What is it for? Am I to delete it or leave it as it is? Which partition should I choose on this step?


User flair doesn't show the full profile picture

I have the following issue for a long time now. Before I was thinking that this issue has something to do with a number of reputation points user has, but then the reputation started growing and the situation didn't change.  Any suggestions on what could be an issue for such behaviour?  UPDATE 1:  Re-uploaded the image and waiting for the User Flair to update the image.  UPDATE 2:  After multiple re-uploading attempts I now have the full picture displaying in my user flair.     Is it possible to mention somewhere down the process of uploading the profile picture that it should be 128x128px in .png format? I know that the Imgur should support most of the common image formats, but as the practice shows it doesn't do it quite well.  You can disagree, but I think doing this would decrease the number of similar to mine cases.


How do you calculate DM XP reward for an AL module without a prescribed time?

I recently started DMing Adventurers League sessions, and I've been told about DM rewards, being particularly interested in the XP I get after each DMed session.  Reading the AL DM guide, I understand that the XP is given in accordance to [a value corresponding to the average party level] × [a number of hours]. It is said that, for Hardcover adventures, the number of hours is the real amount of time the game took, but for modules, it's supposed to be the prescribed amount of time.  For the first adventure I DMed, there was indeed a prescribed duration (2 hours), but then, the next two ones didn't have any (I read the entire adventures, and nowhere would it say "Part X should take you Y hours to do" or anything similar). They were respectively from season 1 and 2 (DDEX01-04 “Dues for the Dead” and DDEX02-02 “Embers of Elmwood”), probably explaining the lack of duration, as I suppose they hadn't started to put in durations at that time.  So, do I just consider modules without prescribed play time as Hardcover adventures for the purpose of calculating my DM XP reward, or is there something I'm missing?


I have created a view in Drupal 7 using views 3 and it is throwing some sql error in preview and the error message is not complete showing here. How can I check this sql complete error message? Is there any option to see SQL generated by view so that I can test the same on mysql client?  Thanks in advance for your help. Umar


If car is going with constant velocity, and hits a man, will the man experience force?

Let's suppose a theoretical case where a car doesn't start with rest but with a high velocity enough to kill a man. The car doesn't change it's velocity i.e no acceleration or deceleration and hits a man after a while(Assume car is moving on straight path). Since, velocity is constant, acceleration is zero. So is the force exerted by the car zero Newton? And If so will the man die?


Why do some technologies have their own StackExchange?

Unix.  LaTeX.  Salesforce.  Magento.  The Stack Exchange API.  These are all developer-oriented technologies...yet questions about them are best asked on their dedicated Stack Exchange sites.  What is it with these (and other) developer-oriented technologies that warrant their own Stack Exchange?


Why is this construct used? Mad or genius?

I'm working with a large SDK codebase glommed together from various sources of varying quality / competence / sanity from Linus Torvalds to unidentified Elbonian code slaves.  There are an assortment of styles of code, some clearly better than others, and it's proving an interesting opportunity to expand my knowledge / despair for the future of humanity in alternate measures.  I've just come across a pile of functions which repeatedly use a slightly odd (to me) style, namely:  void do_thing(foo) {     do {         if(this_works(foo) != success)             break;         return(yeah_cool);     } while (0);     return(failure_shame_death); }   There's nothing complicated being done in this code (I haven't cut 10,000 lines of wizardry out for this post), they could just as easily do:  if(this_works(foo) == success)     return(yeah_cool); else     return(failure_shame_death);   Which would seem somehow nicer / neater / more intuitive / easier to read.  So I'm now wondering if there is some (good) reason for doing it the other way, or is it just the way they always do it in the Elbonian Code Mines?  Edit: As per the "possible duplicate" links, this code is not pre-processed in any sort of macro, it is just in the normal code. I can believe it might be due to a coding style rule about error checking, .


Is (velocity=angular rotation*radius) dimensionally homogenous?

I have been driving myself mad trying to prove it one way or the other, I understand how it is derived and how to use it etc. but it still seems to me to be saying that (m/s)=(rad/s)*(m) which I don't think is dimensionally homogenous, what happens to the radians. Couldn't find anything on the internet about the homogenuity of it. I am probably just being stupid but please if anyone could shed some light on this that would be amazing.


What effects do declaring a variable outside a for loop (for appending to a list) has on later manipulations of items in a list?

I am currently following "Python Crash Course" by Eric Matthes.  I am adding 30 new items to a list using a for loop. All the items are dictionaries. Then I am trying to update first few items of the list using the following code (actual code posted in the end)-  for item in items[0:3]:     if item['someKey'] == 'someValue':         item['someKey'] = 'someOtherValue'         item['someOtherKey'] = 'someDifferentValue'   So, as I am changing only first 3 items, it should change only first 3 items. But it is changing all items in the list if I append to the list using variable declared outside the for loop while adding items in the first place.  #Case-1 items = [] dictionary = {'someKey': 'someValue', 'someOtherKey': 'someOtherValue'} for item in range(30):     items.append(dictionary)   If I run this code and later run the for loop to update some items, then all items in the list get modified. The slicing of the list with [0:3] does not work!  #Case-2 items = [] for item in range(30):     dictionary = {'someKey': 'someValue', 'someOtherKey': 'someOtherValue'}     items.append(dictionary)   So, in this case the update process works as expected. The for loop just updates only the first 3 items. Why does this happen? I have no idea! The list gets created in both the cases just fine. Only while modifying the already created list, the behaviour is differing.    Here's the actual code-  #Case-1 aliens = [] newAlien = {'color': 'green', 'speed': 'slow', 'points': 5}  for alienNumber in range(30):    aliens.append(newAlien)  print(aliens) #Prints the whole list, showing adding dicts went just fine  for alien in aliens[0:3]: #intending change for only first 3 items     if alien['color'] == 'green':         alien['color'] = 'yellow'         alien['speed'] = 'medium'         alien['points'] = 10  for alien in aliens[0:5]:     print(alien) #Shows all five items are modified even though intended for first 3   Here's where this went good-  #Case-2 aliens = []  for alienNumber in range(30):     newAlien = {'color': 'green', 'speed': 'slow', 'points': 5}     aliens.append(newAlien)  print(aliens) #prints whole list, 30 dicts are added  for alien in aliens[0:3]:     if alien['color'] == 'green':         alien['color'] = 'yellow'         alien['speed'] = 'medium'         alien['points'] = 10  for alien in aliens[0:5]:     print(alien)  #Here only first 3 items are modified, as intended     Help me understand the behaviour of the the for loop here. The loop is only supposed to add items and nothing else. How declaring the new dictionary outside the for loop changes how items are modified later?


If $f:\mathbb{R}\to\mathbb{R}$ then $|f(\mathbb{N})|\leq\aleph_0$

I am stuck at this problem for long time:    Prove that if $f:\mathbb{R}\to\mathbb{R}$ is some real-valued function, Then $|f(\mathbb{N})|\leq\aleph_0$.  In other words, prove that there exists a one-to-one function from $f(\mathbb{N})=\{f(n)|n\in\mathbb{N}\}$ to $\mathbb{N}$.    If $f(\mathbb{N})$ is finite then it is clear that $|f(\mathbb{N})|\leq\aleph_0$, But if $f(\mathbb{N})$ is infinite then I got stuck.  Thanks for any hint/help.


On what basis can we combine levels in a factor variable when the target variable is binary?

I am working on a dataset in which a variable has following levels  Levels:      0   1  2  3  4 5 8  Frequency: 608 209 28 16 18 5 7   The target variable is binary. To combine levels in a factor variable while the target variable is continuous, I learned that levels which have an approximately equal mean of the target variable should be combined. This can be found by plotting the boxplot (factor variable vs target variable).   But on what basis can one combine levels of the factor variable when the target variable is binary (i.e., in a classification problem)?


How to flush floats without beginning a new page AFTER the float

I want to flush my float (after an obviously necessary pre-pagebreak, since otherwise the float would be printed there anyway) and continue the text right below this flushed float with no additional page break after the float. My question is, if I have done this correctly.  The problem:  \documentclass{article}  \usepackage{lipsum} \usepackage{graphicx}  \begin{document}  \lipsum[1-3]  \begin{figure}[h] \includegraphics[width=\textwidth]{example-image-a} \caption{I am a figure} \end{figure}  \lipsum[2]  \end{document}   I was curious, if there exists something like \flush:  \documentclass{article}  \usepackage{lipsum} \usepackage{graphicx}  \begin{document}  \lipsum[1-3]  \begin{figure}[h] \includegraphics[width=\textwidth]{example-image-a} \caption{I am a figure} \end{figure}  \flush %error  \lipsum[2]  \end{document}   My current solution:  \documentclass{article}  \usepackage{lipsum} \usepackage{graphicx} \usepackage{float} %does this only affect the single figure with 'H'?  \begin{document}  \lipsum[1-3]  \begin{figure}[H] %is this the right way? \includegraphics[width=\textwidth]{example-image-a} \caption{I am a figure} \end{figure}  %\clearpage %this is wrong  \lipsum[2]  \end{document}


Recently we merged contacts in Salesforce and deleted 4 million duplicate records from salesforce. Now we would like to delete the same records from SFMC.I know once we deleted those records , they would not have synced back to marketing cloud and our synchronized data extension in SFMC would automatically get rid of those merged records. But those customers would be in “All Contacts” which would count against our Contacts and we would like to delete them from All contacts. How should we go about it considering we have 72 million records in All Contacts?Also if I run left join on All Contacts and synchronized data extension,it times out.  Just to add,I am not just trying to identify the numbers of contacts but i have identified them and facing issue with the volume of data. Also I have deleted the customers from Salesforce and i use person account there. Does it make sense to compare All contacts with synchronized DE contacts_salesforce?I only want to filter those 4 million (which i had merged in CRM) from the All contacts.


Why is the centre of mass displaced even when external force is 0?

A pulley fixed to a rigid support carries a rope whose one end is tied to a ladder and a man and the other end to the counterweight of mass $M$. The man of mass $m$ climbs up a distance of $h$ with respect to the ladder and then stops. If the mass of the rope and the friction in the pulley axle are negligible find the displacement of the center of mass of the system.   My question is that the net external force on the system is 0 then why is there any displacement of centre of mass?


Are reservations / advance ticket purchase required for trains in Italy?

In my case the stretch will be between Bologna and Rimini in the summer.  Are reservations required? Or is it realistic to show up at the train station and get tickets / seats on the next train?


I have this 72 GB hard disk that I installed Ubuntu 14.02 LTS 64 bit on. Now, I want to split it and leave 50 GBs for Ubuntu and install in the to-be-created partition the server version of the OS.   The issue at hand is that GParted won't let me change the size of the partition I want to shrink. It reads : minimum size = 72222 mb , maximum size = 7222 mb and obviously doesn't allow me to edit the partition.


Does every element of tensor product look like this?

If $V\otimes W$ is the tensor product of vector spaces V and W, I know that for any basis $(v_i)_{i\in I}$ of V and $(w_j)_{j\in J}$ of W, $(v_i\otimes w_j)_{i\in I,j\in J}$ is a basis of $V\otimes W$, so any $a\in V\otimes W$ is a linear combination of some vectors $v_i\otimes w_j$.   But how can I prove that for every $a\in V\otimes W$ there exists $n\in \mathbb{N}$ and linear independent sets $\{v_1',...v_n'\}\in V$ and $\{w_1',...w_n'\}\in W$ such that $$a=v_1'\otimes w_1'+v_2'\otimes w_2'+...+v_n'\otimes w_n'?$$  This exercise is killing me: I have been trying to think of some way to construct these vectors starting with some fixed pair of bases and the upper fact, but I can't get anywhere! Help!


Create new file with spaces from argument BASH

I need to create new file which contains spaces in it. And it is passed through the argument. This code below creates 2 sepate files. How to create 1 file which will contains space?   touch ""$meno""


What do we mean by live and neutral wire?

In our household circuit we have ac supply of 50 Hz. It means current reverse its direction in every 100th second. I think then, current flows in one direction then another.Then, why do we have live and neutral wires in our household circuit?


Windows(File Explorer,Disk Mngmnt & Diskpart) and MiniTool and sdcard.org's formatter are unable to format my memory card? Should i dispose the card?

I've tried formating my memory card using Window's File Explorer, Disk Management & Diskpart and MiniTool partition wizard and  sdcard.org's sd car formater, no one touched my memory card, Should i dispose it?  Or any of you legends can save me 6 $'s?


Do I need to get identical ram to upgrade a laptop?

I just purchased a Lenovo laptop and I need to expand the RAM. It currently has one stick of ram in it a 4GB DDR3 PC3-12800 Unbuffered NON-ECC 1.35V 1024Meg x 64 by SK Hynix and is capable of having a maximum of 8GB.  I was curious if I needed to buy a pair that matches it perfectly (I've always bought ram in pairs). I really just want to buy one more 4GB stick of RAM and I'm curious if it would be okay if I bought a matching specs wise one of a different brand or if I needed to find one the matches identically to the one I have.


I've been trying to proof that the metric space $(\mathbf{B}(T,X), d_\infty)$ is complete, if $(X,d)$ is complete. The definitions are shown below: \begin{align*}    \mathbf{B}(T,X) = \lbrace f: T \rightarrow X: f(T) \text{ is bounded} \rbrace \end{align*} and, \begin{align*}    d_\infty(f,g) = sup\lbrace d(f(t),g(t)):t\in T\rbrace \end{align*} I have proved that $d_\infty$ is a metric, but I'm stuck at proving that the metric space is complete :( Thanks :)


I'm just read  from Atmel corporation in comparing RSA with ECC cryptography algorithms.  First of all please read these two paragraphs quoted from the article:  P1: Strength of an algorithm     The level of security in systems is becoming a primary concern as you   would expect. Most cryptographic experts recommend that current   systems offer at least 128 bits of security, but what does that really   mean? Note that this is not the same thing as key length as many may   think. Security comes from the combination of the specific algorithm   and its key length. For example, it is generally thought that 128 bits   of security can be achieved with 128-bit AES keys, 256-bit Elliptic   Curve keys, and 3072-bit RSA keys. If implementation issues are   ignored, then these algorithms with those specified key lengths will   generally have the same level of security.   P2: Performance of an algorithm     When it comes to performance at 128-bit security levels, RSA is   generally reported to be 10-times slower than ECC for private key   operations such as signature generation or key management. The   performance disparity expands dramatically at 256-bit security levels,   where RSA is 50- to 100-times slower. RSA’s key generation is also   very slow compared to ECC key generation, with the RSA’s being 100- to   1000-times slower. However, this may or may not be a significant   consideration in systems that generate keys infrequently. It does   matter for certain protocols or policies that require more frequent   key generation. Public key signature validation is generally faster   with RSA compared to ECC, which can provide a benefi   Well, I feel conflicts between these paragraphs. As far as I know, Required time to break an algorithm (An empty of bug one!) is the only thing that determine strength of that algorithm.   And what is this Required-Time depends on?   NK -->  Number of forms of key that is 2^(key-length). NI --> Number of instruction required to check a single key.   In the other words, algorithm A is stronger than algorithm B, only if NK*NI for algorithm A was greater than NK*NI for algorithm B. Am I right?  If so, why ECC-160 is stronger than RSA-1024? I mean, okay, based on the performance paragraph, RSA is only 10 times slower than ECC in this security level, but in return the attacker must check 2^1024 different keys in RSA instead of 2^160 keys of ECC!


Logs growing and took up entire log drive even with log backups

I have a volume just for logs and another volume just for log backups.  The log volume kept  growing until it to run out of space even with log backups taken every 1 minute.   Isn't the backups suppose to free up the space within the log file to be written over again?  It seems like this isn't happening.


Are dangerous rays emitted during Solar Eclipse?

It is said one should avoid staring at Sun as it can damage the eyes, but it is also said that one should not come out in sun during eclipse as it emits dangerous rays. Is that true? If yes, why?


$PGL(n, F)$ and $PSL(n, F)$ are equal if and only if every element of $F$ has an $nth$ root in $F$.($F$ is finite field)  I can show that if  $PGL(n, F)=PSL(n, F)$ then $|F|$ have to be even.I have not any idea how to deal with it. any suggestions ?


If the wave function of two identical fermions is antisymmetric, how can they be identical?

If the wave function of a system of two identical fermions is antisymmetric, how can they be identical? I replace two 'identical' particles and get a different system. This must mean they are not identical. Why isn't this contradictory?


When should I not use a ligature in English typesetting?

Typesetting that goes beyond the scope of basic MS Word (e.g. LaTeX, or even modern Word versions with a good OpenType font) often uses ligatures for certain glyph combinations, the most common being   f + f = ﬀ f + i = ﬁ f + l = ﬂ f + f + i = ﬃ f + f + l = ﬄ.   I would assume, however, that there are cases in which a ligature shouldn't be used. Are there any rules or standards telling me when I should use a ligature and when I shouldn't?


I would like to find $\sum\limits_{k=1}^n \frac{1}{k}\binom{n}{k}$. I tried to write this as an integral but I can't find the result.


Book set underground everyone lives in pods woman wants to see her son

Can anyone help me identify this book please? I read a book in the 80s about a woman living underground in a pod. Everyone had a big tv which gave them news etc (but it was starting to go wrong) and their food was delivered direct to their pod.  They weren't allowed to go to the earth surface as it was supposedly contaminated (post-war?). She gets a message from her son on the other side of the world and she takes the tube train from outside her pod and then some sort of aircraft to see him and eventually gets onto the surface of the earth and breathes the air and meets free people.


I have an ESP 3200 Kodak printer. It does a great job at printing however I am making skateboards and using heat transfer vinyl, and printing it in sections rather than a single page. I have recently ordered 100' of the transfer vinyl and am cutting it into 8.5" x 33" segments. I have changed the page layout to landscape, watched a few YouTube videos on how people do it with Excel to no avail simply because they never even did it themselves. They simply show the instructions and they didn't work, and showed no proof of completing the task. I am using GIMP image editor on a 2009 Mac Pro, and the Preview app. I am able to set the page settings in System Preferences and the page layout in print preview to 214mm x 838mm and 8.5" by 33" respectively, however I believe it's behaving like a graphics program in that it's showing scaling problems on pages after changing the printers default paper size in System Preferences and not printing the entire document, rather one page at a time. There is a possibility it will not print larger than 14 inches however the printer seems to handle the paper correctly and it makes me wonder if there's something wrong in my settings.


How many ways can the product $x_1x_2...x_n$ be parenthesized?


Are there suffixes akin to -phobe and -phile that are less extreme in meaning?

The suffix -phobia means fear of, often irrational fear of.  For example, according to Wikipedia:       or ophiophobia is a particular type of specific phobia,   the abnormal fear of snakes.   Is there a suffix attachable to ophidio- which would describe a person who is not afraid of snakes, except for, say, a coiled rattler encountered on a trail, but who dislikes them and would not willingly share space with one?  Similarly, an  (don't click here if you are at all arachnophobic) is someone who loves spiders.  Is there a suffix for someone who likes spiders but does not love them?  These are Greek suffixes, and the Greeks, theoretically, were in favor of moderation.  So, are there suffixes in use in English, derivable from Greek or not, for moderate like and moderate dislike?    Edit to explain why the question:  "Is there a suffix for loathing" does not answer my question.  My question is NOT about fear and/or loathing.  My question is about moderate dislike (and moderate like).  I can watch a snake cross my driveway with interest, but would not want it in the house or lounging on my patio.   A person who loathed snakes would not be able to admire the smooth motion of the snake as it glided over the rough gravel and disappeared into the woods.  Loathe is very different from moderate dislike; Phobia is very different from caution.


Alternating Series Using Other Roots of Unity

$\sum (-1)^n b_n$ is representative of an alternating series. We look at whether $\sum b_n$ converges and if $b_{n+1}<b_n$ $\forall n\in \mathbb{Z}$.  What if our alternating series is of the form $\sum z^n b_n$ where $z$ is any primitive root of unity.  Do the same tests still apply?  Another question: $\sum 1/n$ diverges but $\sum (-1)^n 1/n$ converges. Is there a $p \in \mathbb{Z}$ where $\sum z^n 1/n$ converges where $z$ is a primitive $p^{th}$ root of unity,  but diverges when $z$ is a primitive $(p+1)^{th}$ root of unity


How do I take a jar file that I have and add it to the dependency system in maven 2?  I will be the maintainer of this dependency and my code needs this jar in the class path so that it will compile.


Let $A\in M_{n,n}(\mathbb{C})$ be a diagonalisable matrix.  Prove $\exists B \in M_{n,n}(\mathbb{C})$ such that $B^{2016} = A$  I can't see why this statement would be true. Perhaps I'm missing something.  Can you assist me please?


I would like to "follow" one specific Stack Overflow user.  By following I mean I'd like to find the "follow the question" + "follow the user" features Quora has.  For example: follow this user's questions/comments/answers on this/these topic(s).  I didn't find any way to follow a user or a question on Stack Overflow the way I do on Quora.     Using user feed would add to0 much noise to my Google Reader. To me the same applies to e-mail + RSS subscription per specific tag, so I don't want to use them.     What do you think?


Is it possible to wipe SSD with strong magnetic force?

I know it is possible to wipe a hard disk, but I'm wondering if something similar can be done to SSD disks as well?


Can message go to spam because of X-AUTH and X-SID fail on hotmail

When email with header as below comes to hotmail, it is put into spam folder. May be this is because of X-AUTH-Result: FAIL or X-SID-Result: FAIL? Or maybe the reason is different?How can I fix this?  x-store-info:4r51+eLowCe79NzwdU2kR3P+ctWZsO+J Authentication-Results: hotmail.com; spf=softfail (sender IP is 114.112.255.122)     smtp.mailfrom=www-data@uniquemobiles.com.au; dkim=none header.d=uniquemobiles.com.au; x-    hmca=fail header.id=sales@uniquemobiles.com.au X-SID-PRA: sales@uniquemobiles.com.au X-AUTH-Result: FAIL X-SID-Result: FAIL X-Message-Status: n:n X-Message-Delivery: Vj0xLjE7dXM9MDtsPTA7YT0xO0Q9MjtHRD0yO1NDTD0w X-Message-Info: 2etWe3f/w1cLzNMFGWUkxI4X8GWjUgRPldCSLaHlMPz8KnnMw4wBLDZs45EYPr3D2LbW9QLPCct0MQQSuVuU4zU05+QEV84llG4Dg802VOeHLX90x3RbeXG0tmVB1as7GPr5ogCj2Y5rfmkYkroQia15I9SlWXAaM4gmU/Jw3y3yzUlB8kZ3Ihqkx5o9o96DUIgQU8BZOI3s1cj++xdMrorb6Gh1fAHR Received: from uniquemobiles.com.au ([114.112.255.122]) by BAY0-MC2-F21.Bay0.hotmail.com with Microsoft SMTPSVC(6.0.3790.4900);  Mon, 2 Sep 2013 21:08:45 -0700 Received: from uniquemobiles.com.au (localhost [127.0.0.1]) by uniquemobiles.com.au (8.14.4/8.14.4/Debian-2ubuntu2) with ESMTP id r8341iG1014318 for <rissa_mol@hotmail.com>; Tue, 3 Sep 2013 12:01:44 +0800 Received: (from www-data@localhost) by uniquemobiles.com.au (8.14.4/8.14.4/Submit) id r8341iuD014317; Tue, 3 Sep 2013 12:01:44 +0800 Message-Id: <201309030401.r8341iuD014317@uniquemobiles.com.au> To: =?utf-8?B?QW50aG9ueSBSaXNpdGFubw==?= <rissa_mol@hotmail.com> Subject: =?utf-8?B?VW5pcXVlIE1vYmlsZXM6IE9yZGVyICMgMTU3NDc1Njc3IHVwZGF0ZQ==?= X-PHP-Originating-Script: 505:Sendmail.php From: Unique Mobiles Sales <sales@uniquemobiles.com.au> Date: Tue, 03 Sep 2013 04:01:44 +0000 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline MIME-Version: 1.0 Return-Path: www-data@uniquemobiles.com.au X-OriginalArrivalTime: 03 Sep 2013 04:08:45.0462 (UTC) FILETIME=[48A58360:01CEA85B]


Error while running on Mule Server 3.7.0 in AnypointStudio

Hi I am running my mule application on mule server 3.7.0 and its showing an error as : -   An internal error occurred during: "Launching pro_run". java.lang.NullPointerException  java.lang.NullPointerException     at org.mule.tooling.maven.ui.launch.MuleWithMavenLaunchDelegate.shouldRun(MuleWithMavenLaunchDelegate.java:52)     at org.mule.tooling.runtime.launch.MuleRuntimeLaunchDelegate.launch(MuleRuntimeLaunchDelegate.java:160)     at org.eclipse.debug.internal.core.LaunchConfiguration.launch(LaunchConfiguration.java:885)     at org.eclipse.debug.internal.core.LaunchConfiguration.launch(LaunchConfiguration.java:739)     at org.eclipse.debug.internal.ui.DebugUIPlugin.buildAndLaunch(DebugUIPlugin.java:1039)     at org.eclipse.debug.internal.ui.DebugUIPlugin$8.run(DebugUIPlugin.java:1256)     at org.eclipse.core.internal.jobs.Worker.run(Worker.java:54)  This is differnet from standard NulPointerException. This situation was arising while starting mule server 3.7.0. I have tried many ways to debug it but can't figure out why its there . Any suggestions or help would be great help .


For a customer I would like to implement SPF for a lot of domains they own, but most of the IP's are the same. I would like to create something like for example Google, so I can use the include: record : _spf.google.com ~all  What to do to make this work right?


When is it kosher to delete one's own answer?

According to , the only restriction on self-deleting an answer is that you can't delete an answer that's been accepted.  But I've also heard of users getting in trouble for deleting (non-accepted) answers, and there's the CC-SA license to consider, so -- quite aside from what is technically possible -- my question is when it's permitted to delete your own answer.  Some cases to consider:   You now believe the answer is incorrect. Your answer is correct, but another answer covers the same territory better. You aren't satisfied with the quality/rigor of your answer, e.g. it's speculative and you didn't back it up (on a site that expects that). Something in the answer embarrasses you and you'd rather just make it go away. Your answer wasn't well-received by the community (whether that's "meh" or "make the rep bleeding stop please"). (I'm sure there are others; this isn't meant to be an exhaustive list.)   Does voting matter, either in absolute terms or in comparison to other answers?  For example, maybe it's ok to delete a lower-voted one but not the top-voted answer, or one with score > N??  There is a badge, Disciplined, for deleting your own post of score 3 or higher.  This tells me that it's sometimes ok to delete upvoted answers.  But I'm not sure how much policy we can infer from badges.  Could we have some clarification please?


How do I make my Eclipse editor look something like this? I'm kind of annoyed by the default layout:


How to output batch file output to BOTH file AND console?

How do I output batch file output to console and file?  I tried using > like this but it only outputs to file.  Powershell.exe -ExecutionPolicy ByPass -File %psFile% %2 %3 %4 %5 %6 > LOG.txt


I found a game with the same name as mine! What should I do?

I published my game  the other day. I checked there was no game on Google Play with the same name. But today I searched for "eyeroller" on Google (Yes, I should have done it a long time ago) and realized there is a game named . They are completely different games, as you can see.  What are the legal implications of this? Can things like trademarks and copyrights be a problem? Should I change my game's name?


I'm doing Exercise 13 in textbook Algebra by Saunders MacLane and Garrett Birkhoff.   If $F$ is a finite field, prove that every function in $F^{F}$ is a polynomial function.  Could you please verify if my understanding is correct? Thank you so much for your help!  Assume $F = \{a_1,\cdots, a_n\}$ and $f \in F^F$. We define a polynomial $p \in F[x]$ by $$p = \sum_{i=1}^n f(a_i) \frac{\prod_{j \neq i} (x-a_j)}{\prod_{j \neq i} (a_i-a_j)}$$ Because the sum and product are finite, they are well-defined. Then we can verify that $f$ is the polynomial function induced by $p$. This completes the proof.


How do I prove $n$ is a Carmichael number?

I am having some trouble with this proof and I need some help heading down the right direction:     Suppose $n = p_1p_2 \cdots p_k$ where $p_i$ are distinct primes and that $p_i - 1 \mid n - 1$. Show that $n$ is a Carmichael number, that is, that $a^{n - 1} \equiv 1 \pmod n$ for all $a$ with $\gcd(a, n) = 1$.   Thank you for your help.


String.Format in javascript as in vb.net

Is there any code for String.Format in javascript as like in vb.net?   val=String.Format("{0:n" & ratedis & "}", to_arr(0))


I have heard many people tell me that the tensional force is bi-directional. Consider the following case where a (mass-less) rope is used to transmit tension.  The rope is being pulled (by hand) with a force of 5 newtons. Thus the mass (along with the rope) will have an acceleration of 5 ms^(-2). (Neglect friction)    1) Considering a point P on the rope, have I represented the tensional force on the rope correctly?  2) By Newton's Third Law, if the rope is pulling on the block, the block must exert an equal and opposite force on the rope. So, shouldn't the body not have any motion? A similar question was asked here: . According to the answer provided, it is the force of the muscles that is responsible for the resulting acceleration.   So then what force is transmitted across the rope? It has to be the force of the muscles and not any other force since the tension in the rope is 5 newtons. But if it is so, the force exerted by the block on the rope (reaction) should also be 5 newtons. This means that the object will have no motion! Am I misunderstanding something here?


How can I change the color of the lines (the frame) in a tabular environment? In the following MWE:  \begin{tabular}{c|c|c} a&b&c \\ \hline d&e&f \\ \hline g&h&i \end{tabular}   I would like the horizontal and vertical lines of the table to have, say a blue color.


Why the shape (sB) is unknown in the following code ? How to avoid this ?  \documentclass[]{standalone} \usepackage{tikz,xparse} \usetikzlibrary{calc}  \tikzset{pics/.cd,     % Marque croix     Cross/.style args={#1 and #2}{%         code = {%         \draw[#2,rotate=45,scale=1.4] (0,#1 pt) -- (0,-#1 pt) ;         \draw[#2,rotate=-45,scale=1.4] (0,#1 pt) -- (0,-#1 pt) ;         }     },     Cross/.default={2 and black} }  \NewDocumentCommand{\Segment}{mO{}}{%     \begin{scope}[#2]     \path    (0,0) coordinate (sA) pic {Cross={1.5 and gray}}         -- (#1,0) coordinate (sB) pic {Cross={1.5 and gray}} ;     \draw (sA)--(sB) ; % Can't reuse (sB)     \end{scope} }   \begin{document}     \begin{tikzpicture}     \Segment{1.5}     \end{tikzpicture} \end{document}


How to create and export complex symbology?

I've got punctual geometries that I'd like to represent in a desktop and a web application, using complex symbology, like this :    My idea is to use a symbology editor to create a SLD file that defines the symbols. I used QGis to create the symbology and then tried saving it into a SLD file. The problem is that symbols are simplified and instead of the symbol I created, I get this one:    Do you know about a SLD editor that supports complex symbology?  Do you have any other suggestion different from creating a SLD file?


I have no idea how prove that $$\{(z_0,\ldots,z_n)\in\mathbb{C}^{n+1} \quad| \quad z_0^d+z_1^2\ldots+z_n^2=0, \quad |z_0|^2+|z_1|^2\ldots+|z_n|^2=2\}$$ is a $(2n-1)$-compact manifold.  How give the charts. For $n=1$ and $d=2$ not distinguish which 1- manifdold is?


I know about the "cooperative" threading of ruby using . How can I create real "OS-level" threads in my application in order to make use of multiple cpu cores for processing?


I'm having a problem with centering my figure captions. Particuarly, I know that we can use \usepackage[justification=centering]{caption} to center captions, however, I'm interested in just centering a specific caption. I've read the caption manual but no luck, so my question is: How can I center a specific caption?


How do I get list of all tables in a database using TSQL?

What is the best way to get the names of all of the tables in a specific database on SQL Server?


Where can I find an administrative boundary shapefile for Monaco?

I am looking for an administrative boundary file (preferably in ESRI shapefile format) for the divisions of Monaco namely:  Condamine Fontvieille Jardin Exotique La Rousse Larvotto Les Moneghetti Monaco-Ville Monte-Carlo   I have looked at a few websites like diva-gis, nationmaster, geofabrik, statsilk and eurostat but non of the files for Monaco are divided by the above areas, only the outline of Monaco itself. I need something akin to this image below...


When I click on and element with a class of tool the alert box should show up but nothing happens, no errors in the console either.  I'm pretty sure the issue I'm seeing is an event delegation issue, I just can't figure out where I'm going wrong.  So the first snippet, the if statement loads a bit of HTML into the #tools element and the second snippet is when a user clicks on an individual .tool element that was loaded into #tools.  I've tried adding the alert code block into the if code block but didn't make a difference.   Snippets  if ($("#tools").length) {     data = {}     data['id'] = $("#tools").data('id');      ajaxCall("#tools", 1, data); }     $("#tools .tool").on("click", function(e) {     alert("1234");     e.stopPropagation(); });   HTML Example

1

12

123

1234

   *AJAX Function**  function ajaxCall(element, callId, dataIn) {     var limit;     var data;     data = {id: callId, data: dataIn, element: element};      $.ajax(     {         type: "POST",         url: "calls/",         data: data,         success: function (data)         {                             $(element).html(data);         },         error: function (jqXHR)         {             $(element).html(jqXHR.status + " - " + jqXHR.statusText);         }     }); }


How to get a random element from a list in python?

I want to generate a random  element from a list that is already given by myself or a list taken as an input .


Does LIGO GW detection methodologically constitute discovery of two specific black holes (as astronomical objects)?

It is said that the gravitational waves (GW), recently detected by LIGO, correspond (according to Einstein General Relativity theory equations) to the effect of two black holes merging (with the masses of both colliding black holes and the mass of the black hole, which resulted due to that merger, being estimated).  Does the above method (detection of gravitational waves) constitute acceptable scientific method of proving with regards that the source of those waves was indeed the merger of two black holes (as definitely existing astronomical objects), or is it still at best currently possible implied assumption?  Since in the given case, existence of black holes is derived using two steps of inference from the General Relativity Theory mathematical model, should there be at least two independent of each other methods to claim the discovery of those two black holes as astronomical objects?  As an alternative, could LIGO signature detected GW possibly have been produced by collision/merge/annihilation of some matter and antimatter objects (this one is highly hypothetical assumptive question and I am asking it just to illustrate my point that the collision of two BHs, implied as the cause of LIGO detected GW, perhaps should be considered as just highly probable but not absolutely established astronomical fact)?  Could this issue (specifically with regards to detection of two black holes merge and existence of resulted from that merge single black hole) be compared (in the sense that both relied on indirect evidence analogy) with the issue of existence of Planet 9 (per California Institute of Technology astronomers Konstantin Batygin, a theoretician, and Mike Brown), which is considered at this point as just a hypothesis (with all evidence of its existence being indirect and relying on the calculational model)?    P.S. It is interesting (see below link)    that at the beginning of above article the word "discovery" was only applied by Stephen Hawking to the detection of gravitational waves as such, but further the term "discovery" was extended as:  "This discovery is the first detection of a black hole binary system and the first observation of black holes merging.”  Further on  "Asked what more could be discovered if scientists scanned for gravitational waves, he said: “Apart from testing general relativity, we could hope to see black holes throughout the history of the universe. We may even see relics of the very early universe during the big bang at the most extreme energies possible.”"  This question is a refinement of the previously asked by me question   ,   which was diluted (Mia culpa) by another issue (related to classification of black holes).  I would like to see here an answer, which would more in general cover the subject of methodologies, with regards what constitutes discovery in PHYSICS (such as the phenomena of gravitational waves) versus discovery in ASTRONOMY (such as discovery of black holes, as astronomical objects). With regards to LIGO detection, I think that it amounts to discovery (in the field of Physics) of gravitational waves (as physical phenomena), but I do question whether LIGO detection constitutes a discovery (in the field of Astronomy) of specific black holes (as astronomical objects) - the latter one, IMHO, should be characterized as highly plausible very probable hypothesis ...  Could someone offer me the historical ASTRONOMY precedent when the second degree of inference (from the mathematical model, being associated with the theory of Physics) was accepted as the discovery of the astronomical object?


Proving $\lim_{h \to 0} \frac{|h|^\alpha}{h}=0$ given $\alpha > 1$.

I've stumbled upon that limit in the book that I'm studying (Spivak's Calculus). At the current stage of the book, this is a trivial task if $\alpha \in \mathbf Q$. But the problem statement doesn't specify anything about $\alpha$, except that $\alpha > 1$, so what if $\alpha \in \mathbf R$? At the current stage there is no Chain Rule, L'Hopital's Rule, exp/log, integrals, series. I've attempted to show that $$\lim_{h^+ \to 0} \frac{|h|^\alpha}{h}=\lim_{h^+ \to 0} h^{\alpha - 1}=0=\lim_{h^- \to 0} -(-h)^{\alpha - 1}=\lim_{h^- \to 0} \frac{|h|^\alpha}{h}.$$ I've tried:  Something like $0<h<\delta = \epsilon^{\frac{1}{\alpha - 1}} \implies 0<h^{\alpha - 1}<\epsilon$, but I'm not sure how to prove the general statement that $\forall x,y,a \in \mathbf R, a > 0, \ \ 0 \leq x < y \implies x^a < y^a$. Also I can only prove the existence of the roots like $\epsilon^{\frac{1}{n}}, n \in \mathbf N$. Prove that $f(x)=x^\alpha, \alpha > 0$, is continuous. Using limits multiplication rule for that would not work for irrational $\alpha$. Showing continuity through differentiability is problematic, I can prove $(x^n)'=nx^{n-1}$ only for rational n (this also hinders the proof of the statement in 1., i.e. that $f(x)=x^\alpha, \alpha > 0$ is an increasing function on $x \geq 0$).  Nevertheless, the problem is given at this stage, so what am I missing here?


Image of a normal space under a closed and continuous map is normal

$p : X \to Y$ is continuous, closed and surjective, and $X$ is a normal space. Show $Y$ is normal.   There is a hint, which I'm trying to prove: show that if $U$ is open in $X$ and $p^{-1}(\{y\}) \subset U$, $y \in Y$, then there is a neighbourhood $W$ of $y$ such that $p^{-1}(W) \subset U$.  I have a candidate for $W$, namely $W=Y\setminus p(X \setminus U)$. I did prove that this $W$ is open, and that $p^{-1}(W) \subset U$, but I don't see how $y \in W$. I think this would require injectivity of $p$.  I have also shown that $y \in p(U)$ and that $W \subset p(U)$, so if also $W \supset p(U)$, then $y \in W$.   Can anyone help me?


Is it possible to load Iframe from a lightning component?

I need to load Iframe from a lightning component in the community site( Napili template). Once I load Iframe from a lightning component I'm getting following error.     because it violates the following Content Security Policy directive:   "frame-src https: mailto:".   How can I load Iframe from a Lightning component?


Is it "No band practice" or "No band practise" in British English?

I understand that one is a noun and one is a verb. But is it correct to say "There is no band practice today" or "There is no band practise today"  UPDATE: I am not asking for the correct spelling of the word "practice" or "practise". The dictionary definition is clear. I am asking which usage is correct in this example sentence.


I'm debugging a small program in java, a strange error occurred:  import java.util.*; public class DebugNine3 {    public static void main(String[] args)    {       ArrayList products = new ArrayList(3);       products.add("shampoo");       products.add("moisturizer");       products.add("conditioner");       Collections.sort(products);       display(products);       final String QUIT = "quit";       String entry;       Scanner input = new Scanner(System.in);       System.out.print("\nEnter a product or " + QUIT + " to quit >> ");       entry = input.nextLine();       while(!entry.equals("quit"))       {          products.add(entry);          Collections.sort(products);          display(products);;       }    }     public static void display(ArrayList products)    {       System.out.println("\nThe size of the list is " + products.size());       for(int x = 0; x <= products.size(); ++x)          System.out.println(products.get(x));    } }   Note: DebugNine3.java uses unchecked or unsafe operations. Note: Recompile with -Xlint:unchecked for details.  can someone explain why this message appeared?


How does the shape (form; not cross-section) of a spring impact performance?

Cylindrical compression springs are everywhere and then some applications choose other forms like rectangular or unique polygonal form. What impact does the form of a compression spring have and how do you calculate an optimal solution?


Disabling SET Statements / Forcing SET Options in SQL Server 2008R2/2012

I am currently working with a SQL Server 2008 R2 database which uses the following SET commands frequently:  SET ANSI_NULLS { ON | OFF } SET QUOTED_IDENTIFIER { ON | OFF } SET ANSI_PADDING { ON | OFF }   While I was researching these settings I stumbled across the following note for ANSI_NULLS on Microsoft Technet ():     In a future version of Microsoft SQL Server ANSI_PADDING will always be ON and any applications that explicitly set the option to OFF will produce an error. Avoid using this feature in new development work, and plan to modify applications that currently use this feature.   Because of this I would like to enforce a "global" setting. I have been searching for the better part of a day but as I understand it you can always change these settings. To be completely sure I would like to ask here:  Is it possible to either enforce a setting like ANSI_NULLS ON or to disable the possibility of changing these settings on "any" level?  I would like to use this to test if the database would "survive" if the ability to set a specific option to OFF is disabled.  I hope I was able to describe my problem. This is not my first language.  Thanks in advance.


Norm equivalence (Frobenius and infinity)

I am trying to prove the matrix norm equivalence for norms 1, 2, $\infty$ and Frobenius.  I have managed to solve find the constants for $||.||_{1}$ and  $||.||_{2}$ but I cannot see how to continue if I want to prove the following:  $||A||_{\infty} \leq \sqrt{n}||A||_{2}$   and the ones for Frobenius:  $||A||_{F} \leq \sqrt{n}||A||_{1}$  $||A||_{F} \leq \sqrt{n} ||A||_{2}$  Any help is appreciated. Thank you for your time


I am reading a book on combinatorics and one of the exercise questions asks:  Suppose a positive integer N factors as $p_{1}^{n_1}.p_{2}^{n_2}...p_{m}^{n_m}$ where $p_1, p_2, ..., p_m$ are distinct prime numbers and $n_1, n_2,..., n_m$ are positive integers. How many different positive integers are divisors of N?  I thought of writing the prime factors separately:  $$p_1p_1p_1...p_1{\times}p_2p_2...p_2{\times}p_3...p_mp_m...p_m$$  Then for each of the p's you could choose to include it or not include it, giving a count of:  $$2^{n_1+n_2+...+n_m}$$  But this is of course overcounting it since, if I chose 2 $p_1$'s, I could have chosen any two from the $n_1$ $p_1$'s and it would result in the same number.  How do I proceed from here?  Thank you.  EDIT: Questions answered in the comment.  Answer is $(n_1+1)(n_2+1)...(n_m+1)$ since one can chose to include between 0 to $n_i$ instances of the $i^{th}$ prime.


What is the next number having the same number of bit 1s?

You are given a number, $A$, and you have to determine a number, $B$, such that $B>A$ and the number of $1's$ in the binary representation of $A =$ number of $1's$ in the binary representation of $B$.  What is the smallest $B$?


What's the name for expressions like "food, glorious food"?

Is there a literary term for the construction of the phrase food, glorious food? I'm assuming something related to its brevity and repetition.   Thanks.


If the universe is expanding then why does the distance between Sun and the Earth is not expanding?

It has been proved that universe is expanding in the accelerating way. If that is true than the space between the Sun and the Earth must also be expanding. But it is not so, why?


Do native speakers ever make pronunciation mistakes?

I've been thinking of this and I'd appreciate if a native speaker could reply.   Many times I see on the internet lots of English-related material about how to pronounce correctly, and that is mainly because in English you don't pronounce words as you write them.   I know that pronouncing a word correctly is an issue (sometimes unnoticed) to many students and even to advanced ones I would just like for a native speaker to share their insights on the matter and how/if this has been an issue to them.


Large spaces between words in subsection title

I have a problem with the spacing in the header of a subsection. Only this particular heading has large spaces. It looks like this:    Here is MWE:  \documentclass[11pt,twocolumn]{article}  \begin{document}  \section{Implementation}  \subsection{Reciprocal Velocity Obstacle (RVO)}   \end{document}   How do i fix this?


Philosophical question about Pi and connections in maths

Pi is the ratio of circumference of a circle to its diameter.  Okay. Got that, easy enough. Now, why does the following equality hold true?  $$ \frac{\pi}{4} = 1 - \frac{1}{3} + \frac{1}{5} - \frac{1}{7} + \ldots$$  Why do we get closer to Pi from summing up many rational fractions? Granted, we can do a little bit of calculus here, find out that it all comes down to either fundamental theorem of calculus or Taylor series. Either route you pick the key here is the fact that derivatives of inverse trigonometric functions are rational or at least non-trigonometric.  If we dig deeper, it becomes clear that it all depends on our choice of units for trigonometry. Why are radians the right way to measure angles? It all boils down to the well-known limit:  $$\lim\limits_{x \to 0} \frac{\sin x}{x} = 1 $$  The above equality is true if and only if $ x $ is measured in radians. Why does sine have to be $ 2\pi $-periodic for that limit to equal 1?  My guess is that period of sine is $ 2\pi $ because it's the only value "makes" that limit equal 1. That's the only sane explanation I could devise. Isn't there a more obscure mathematical connection here? Resolving the problem via falling in a virtuous circle is the only way to go here?  Still, why is it $ 2\pi $ and not, say, $ \sqrt{42} $? I apologize in advance for insufficient clarity of my writing, English is not my mother tongue.


Answer isn't deleted even after 7 people recommending deletion

I reviewed an answer in the Low Quality queue yesterday and chose "Recommend deletion", but it doesn't seem to have done anything other than adding the autocomment. Other than the comment there's no evidence of review ever happening.  The review was completed with 7 people recommending deletion but the answer is still there, which suggests that no-one managed to flag it.       The review action doesn't show up in , only the autocomment is there:    The flag is not in my flag history (edit: and apparently it shouldn't be).    What's going on?


Maximum eigenvalue of a hollow symmetric matrix

Is the maximum eigenvalue (or spectral radius) of the matrix with the following form equalled to row or column sum of the matrix?  $$ A=\left( \begin{array}{cccc} 0 & a & ... & a \\ a & 0 & ... & a \\ : & : & ...& :  \\ a & a & ... & 0\end{array} \right) $$  The matrix is square with dimension $n \times n$ where $n = 2,3,4,...$, hollow (all elements in the principal diagonal = 0), symmetric and all off diagonal elements have the same value.  Is the spectral radius of such matrices = $(n-1)\times a$? Why?


why there is less space in my external HDD than it supposed to have

I have purchased a WD 1 TB external HDD.From the size specified i should expect i will have 1 TB of disk space.But it came with 930 GB of space.I am getting  approximately 70 GB of less space.  Is it natural to have less space than specified amount?  Is there any way to recover those 70 GB space?   70 GB is not such a small amount.If i can retrieve those spaces it would be great.Thanks ......


Why is a packet is not sent until ACK is received when window size is sufficient

The considered application (server) has a number of clients connected. It processes each message from the client and sends two output messages. The output messages are generated sequencially and written to the socket. I observe that occassionnaly the second output message is delayed by a big time for a client. I'm trying to understand the reason for this.   Below is the filtered TCP flow between the application and the client captured from the client side.     14908 is the input message from client. 14910 and 15337 are the two ouput messages 14910 is not delayed. But 15337 is delayed around 40ms. As I can see, the 15337 packet is not sent until the ack 15336 is received.   The application sends a packet to TCP layer if the socket does not return EWOULDBLOCK or EAGAIN . I'm assuming the socket is not blocked because the window published in #14908 is 1424 and #15336(len=229) shouldn't send it to EWOULDBLOCK.  So can you please help me understand what causes the TCP layer from delaying the sending of #15337 until the ack for #15336?