Would a mini-blackhole collision with Earth cause heating?

Let's forget about the probability of this event. I am a mad scientist on the Moon, I created a micro black hole of the diameter $r=0.5cm$. I have to be fast before it evaporates due to Hawking radiation, but before shooting it to the Earth, doubt stops me.    As soon as my blackhole reaches the ground (and even before), it starts sucking material. Everything it "touches" would disappear under the event horizon. It couldn't create shockwaves and alike. How could then it produce the massive blast of heat and destruction it supposed to? I consider two scenarios:   The black hole travels to the Earth with relatively low speed. This way the (zero) momentum of the material it sucks during interaction would slow it down enough to finally stop. After that, it would slowly but surely consume the whole Earth. This is the less interesting problem therefore.   The black hole hits Earth with a significant portion of light speed. It wouldn't even bother with the sucked material, even the whole planet couldn't stop it. Speaking of an asteroid, this would be the holly way of total destruction. But I have an event horizon...     So, there is the question:    In both cases, would it, and if, by what effect and how much would the black hole heat up the impact zone?    I have some theories. Maybe the gravitational turbulence the encounter causes locally would cause enough heat to be destructive. This seems to work only for the first case: a speeding hole would have little time to accelerate the ground material. Maybe the material it sucks up would emit strong enough radiation. Or the collision's energy would indeed only increase the black hole's mass, and I would only get a neat 0.5cm wide hole in the ground with slowly (?) rising diameter. (In this case, I'd wonder if any friction-like phenomena would occur apart from the momentum of sucked material...)  Note: I am not interested in the effects of Hawking radiation of the black hole, though I don't know how significant would it be. If it is so big it makes the neglection unrealistic, feel free to produce a bigger mini-blackhole.


Planning to buy new Lens for Nikon D5100

Currently I am using Nikon D5100 DSLR camera with default kit lens 18-55MM lens. Now I am planning to buy some new lens but i am confuse because still i am new to photography. Mainly I want to do landscape photography and sky photography.But since kit lens is not having very good zooming so can you just suggest me some economic lens which i can use with my Nikon D5100.  Please check out my sample picture and let me know that is this correct time to upgrade to lens of continue with kit lens and learn more.


I want a source containing the proof of Steinitz Isomorphism Theorem stating:     For any Dedekind domain $R$ and any two nonzero ideals $I$ and $J$ of $R$ we have $I⊕J≅R⊕IJ$.   Thanks!


In this code the result is failure sending mail as message box shown,      please guide me where   i did mistake.             i tried it in many ways i didn't get. Thanks in advance   private void button2_Click(object sender, EventArgs e)   {    try     {       MailMessage msg = new MailMessage();      msg.To.Add("someone@gmail.com");      MailAddress address = new MailAddress("someone@gmail.com ");      msg.From = address;      SmtpClient client = new SmtpClient();      client.DeliveryMethod = SmtpDeliveryMethod.Network;      client.EnableSsl = true;      client.Host = "smtp.gmail.com";      client.Port = 25;      NetworkCredential credentials = new NetworkCredential("someone@gmail.com", "password");      client.UseDefaultCredentials = false;      client.Credentials = credentials;        client.Send(msg);      } catch (Exception ex) {       MessageBox.Show(ex.Message);    }   }     <smtp deliveryMethod="Network">    <network host="smtp.gmail.com" port="25" userName="someone@gmail.com" password="password" />  </smtp>


Why is it wrong to use non-nested cross-validation?

Imagine I have a classifier with some parameter $a$. I want to perform parameter optimisation and model selection. Imagine that my grid for the values of $a$ has three values 1,5 and 10 and I want perform 10-fold cross-validation as follows:   For each iteration, the dataset is partitioned into a 9:1 ratio of training and testdata, whereby at each iteration the two consists from other sampled datapoints of the full dataset (which is the description of 10-fold cross-validation) Now, each of these iterations is done three times: one time for each parameter value.   Hence I end up with 30 iterations (10-fold cv basically, but for each parameter once) and pick the parameter which on average performed best. I am aware that this chosen model has not YET been tested on new data. However during all the iterations, since test and training set have been disjunct and independent, it's performance has been evaluated on this unseen test set. So why is this approach incorrect (as in comparison with nested cv with an inner and outer loop)?


This question is not same as explaining Twin paradox. This question does expect that the travelling twin will age less. The question in here is what causes the travelling clock to slow down, which is verified at the end of the journey. If the cause is acceleration, then why the consecutive accelerations in opposite directions have opposite effects on clock speed.  I am looking for conceptual description, not a lot of mathematics.  Again, this is long question, please be patient.  Down voters, please share your thoughts as well.  Start -   Two twins are on earth with their clocks synchronized.  One stays on earth, the other makes a fast and long, quick round trip journey and then they compare the clocks.   Q1 - Is it expected that the trip making clock will be far behind the one that was left on earth? Obviously if it is true, then the difference will depend upon how fast and how long the trip was.  If the answer to above is true, then we know that the clock of the travelling twin did really slow down.   Doesn't this tell us that the ticking of clock was actually slowed down due to initial acceleration, then continued to run at slower rate (as compared to the one on earth), then sped up again during retardation at far end.   Suppose the travelling twin remained at 0 relative speed wrt earth for a day or so. During this day or so, both twins can verify that the clock of travelling twin is now behind, but tick rate is same during that day. Meaning the travelling clock was really ticking at slower rate.  Then the travelling twin started accelerating back toward earth. The clock of this twin would slow down again.  The retardation just before far end and the acceleration in start of return journey, are actually acceleration in same direction.  But the first part of this acceleration (retardation) sped up the clock, and second part slowed it down.   When the travelling twin reduces speed again before reaching earth. This reduction in speed again speeds up his/her clock so that the tick rate is same for both twins now. But the difference in clock times would be double of what it was noted at the far end. Consider all accelerations same rate.  Q2 - Do we really understand how the "same direction" acceleration sometimes slows down the speed and sometimes speeds them up.   But if answer to Q1 is yes, then this slow down and speeding up of clocks always seems to be equal and opposite if you consider any two consecutive changes in speed that pass through the 0 relative speed point.  Or, there is no real change in tick rate, and the slowdown is just relative and perception? And when the travelling twin comes back to earth, its clock will show same time as that of the other twin?


I found a directory on my machine called "Previous System" that looked old and useless and I tried to delete by dragging to the trash and emptying the trash. That failed to delete the directory, because emptying the trash gave me messages such as The file 'Applications' is in use. or The file '.MobileBackups' is in use.  So I dragged that directory out of the trash and went into the terminal to delete it, but it seems undeletable. For example:  $ cd ~/Desktop $ sudo mv Previous\ System prevsys $ sudo rm -rf prevsys rm: prevsys/.MobileBackups/Computer/2014-10-20-143930/Volume/Applications/CrashPlan.app: Operation not permitted rm: prevsys/.MobileBackups/Computer/2014-10-20-143930/Volume/Applications: Directory not empty rm: prevsys/.MobileBackups/Computer/2014-10-20-143930/Volume: Directory not empty  rm: prevsys/.MobileBackups/Computer/2014-10-20-143930: Directory not empty rm: prevsys/.MobileBackups/Computer: Directory not empty rm: prevsys/.MobileBackups: Directory not empty rm: prevsys: Directory not empty $ cd prevsys $ sudo ls -l total 0 drwxr-xr-x+ 3 root  wheel  102 Nov 18  2013 .MobileBackups $ sudo cd .MobileBackups $ pwd /Users/blah/Desktop/prevsys   I've never seen a directory that I can't cd into as the superuser, so I'm not really sure, how do I get rid of this thing? Thanks.


What would the universe be like if Electroweak symmetry were unbroken?

Possible Duplicate:          What if the Higgs did not have a "Mexican hat" potential and the therefore it's vacuum expectation value were zero. Then the elementary particle masses would be zero, so the electron, W+, W-, Z and quarks would all be massless. Would a proton with non-zero mass be possible since most of the proton mass comes from the binding energy of gluons which are already massless?  The weak force would be long range and fall off like $1/r^2$. I assume the Z would take the role of the photon. How many kinds of weak charge are there? Would like charges be repelled and unlike charges be attracted via the Z? Would there be something equivalent to magnetism?  What would the massless W do? Would the long range weak "W" force change the electrical charge values of electrons/neutrinos and quarks? How weird is that!  I know, we wouldn't exist to see all of this, but I am curious about how this would all work.


I'm using Illustrator and doing a typography course. In order to create a bit more visual weight, I'm trying to mimic the idea of sound resonance through color. In this image  I simply use the blend tool to duplicate the type and after creating outlines and expanding the shape I try using the radial gradient as I need the center to be dark and the last blocks of type to be grey.  What happens instead is that every letter gets its own gradient. Can you guys think of a smart way to go around this. I've found a solution to my issue by manually lowering the opacity, but I'm wondering if there's a more efficient way to approach this. Thanks


How to create single instance of class and use it multiple times?

I am creating a object (bb) of Box class.and storing  25 to its attribute value. The object will be created and it will have memory.Now I want to create new instance of Box class but i want it to point it to the same object created for bb and not allocating it new memory again.For example if write Box cc new Box(); and print out cc.value it should print 25.It should not allocate new memory.That is every time we create object it should refer to bb .For example Box newOne = new Box(); and newone.value should give us 25.Is this possible? I don't know if i have described the problem well.I came across this type of question recently in an exam.  Box bb = new Box(); bb.value = 25; Box cc = new Box();//It should not allocate new memory it should refer to  //the previous memory that we used for bb. System.out.println(cc.value);//It should give us 25  class Box{   int value; }


factor-square property (FSP) of polynomials

The Factor Square Property (FSP) is the divisibility of the polynomial $f(x^2)$ by $f(x)$.   Is $x^2+x+1$ the only FSP irreducible polynomial of degree $2$ ? Are there other linear polynomial besides $x$ and $x-1$ with FSP? Do we have other FSP irreducible polynomials of degree $3$ or $4$? Any of these have integer coefficients?? Are there any other observations you can make about polynomials with FSP?


How to fix Terminal error DYLD_ environment variables being ignored because main executable (/usr/bin/login) is setuid or setgid?

Any time I open a new terminal window (independent of terminal app), the console stderr displays dyld: DYLD_ environment variables being ignored because main executable (/usr/bin/login) is setuid or setgid before the first bash prompt.  The start of this error coincided with my install of 10.8.  How can I get rid of that message?  Below is my .bash_profile:  export PS1="\u@MBP:\W ->"  ## # Your previous /Users/segiddins/.bash_profile file was backed up as /Users/segiddins/.bash_profile.macports-saved_2012-04-19_at_21:00:04 ##  # MacPorts Installer addition on 2012-04-19_at_21:00:04: adding an appropriate PATH variable for use with MacPorts. export PATH=/opt/local/bin:/opt/local/sbin:$PATH # Finished adapting your PATH environment variable for use with MacPorts.


Icloud Uploading Stuck. Does anyone know why it actually does this?

The attached image is what's currently displayed if I click on the wheel in Finder. Is it related to 'bird' and if so how?     But does anyone know what causes this to happen?  OK. Thanks to another post, I'm on the trail of the culprits.  robert@zeus brctl-dump % brctl monitor com.apple.CloudDocs|grep %   o /com~apple~CloudDocs/Downloads/badaboombb_ot/fontinfo.txt ↑ 2 KB (1834) 95.0%   o /com~apple~CloudDocs/Downloads/backissuesbb_ot/fontinfo.txt ↑ 2 KB (1834) 95.0%   o /com~apple~CloudDocs/Downloads/Afans Live Filters - for Designer 1.6.zip ↑ 92 KB (91525) 95.0%    And so on for a maybe hundred files in my case. All files show the little UP arrow, indicting that uploading is still taking place, and the percentage left at the end of the file info. All of them 95% SO it seems to be getting stuck at 95%?  Also, some of the files listed no longer exist. I've long since deleted them, yet here they are still in the upload list. What to do.  I found this useful info in another post here.   ======== Progress of sorts ========  In all this - Photos is syncing perfectly. Anything from any of my devices, iPhone and iPad is syncing perfectly. It's just this Mac that seems to be stuck.  Doing a 'log show | grep Cloud streams a LOT of information about what's happening. And this looks interesting, and there is a lot of it repeating. Does this indicate something is Stuck and throttling iCloud?  2020-01-22 13:18:20.328917+0000 0x459b     Error       0x807e               469    14   bird: (CloudDocsDaemon) [com.apple.clouddocs:default] [ERROR] Failed to remove sync root bit [22: Invalid argument] 2020-01-22 13:18:20.329095+0000 0x459b     Error       0x807f               469    14   bird: (CloudDocsDaemon) [com.apple.clouddocs:default] [ERROR] Failed to remove sync root bit [22: Invalid argument] 2020-01-22 13:18:20.329174+0000 0x459b     Error       0xbc20               469    14   bird: (CloudDocsDaemon) [com.apple.clouddocs:default] [ERROR] renameat(-1, '<private>', 21, '<private>', 4) failed after trying to fix permissions [17: File exists] 2020-01-22 13:18:20.329313+0000 0x459b     Error       0xbc21               469    14   bird: (CloudDocsDaemon) [com.apple.clouddocs:default] [ERROR] -[BRCStageRegistry moveFromStage:toPath:fileName:error:]: (passed to caller) error: Error Domain=NSPOSIXErrorDomain Code=17 UserInfo={NSDescription=<private>} 2020-01-22 13:18:20.329422+0000 0x459b     Fault       0xbc22               469    14   bird: (CloudDocsDaemon) [com.apple.clouddocs:default] [CRIT] UNREACHABLE: Failed to move from fault stage to live Error Domain=NSPOSIXErrorDomain Code=17 UserInfo={NSDescription=<private>}


Terminal - Weird spaces included when typing fast

Whenever I want to use the pipe operator in the terminal, I get a weird kind of "bug":    As is shown in the image above, I can type the exact same command twice and it will sometimes register it or sometimes include some spacing in the command, as can be seen in the error message. The only difference between the two commands was the speed I typed them, with fast typing the char sequence "| " (without the "") leading to the error. I've checked in the terminal settings if this sequence somehow triggers a shortcut, but I did not find anything.   In case it matters, I'm using a swiss keyboard. The layout is as follows:    To produce the "|" character, I press "alt + 7". Does anybody know what the cause of this problem is?


When is $n^{2015}+n+1$ prime, $n \in \mathbb{N}$?   I think this seems true only for $1$.  I tried to show that $4n-1,2n+1,2^{n+1}-1$ divides the given expression but didn't succeed. I have only thought about this through the way of modular arithmetic. Someone suggested to me to use the complex roots of this equation, but didn't specify how.  Are there any other results I can use for this problem(I may not know them)?  Please provide only hints if you do solve it. Thank you.


I am trying to calculate the expected value of a Normal CDF, but I have gotten stuck. I want to find the expected value of $\Phi( \frac{a-bX}{c} )$ where $X$ is distributed as $\mathcal{N}(0,1)$ and $\Phi$ is the standard normal CDF.  I know I can transform $\frac{a-bX}{c}$ to be a normal random variable $\mathcal{N}\left(\frac{a}{c},\frac{b^2}{c^2}\right)$ where $\frac{b^2}{c^2}$ is the variance of the normal random variable. I'm not sure if this helps though.  I think that the expected value of a CDF is $0.5$ but since $\Phi$ is the CDF of a standard normal CDF and $\frac{a-bX}{c}$ is not standard normal I do not think the expected value should be 0.5. I tried integrating the CDF, but I do not believe I did it correctly.  When $a = -2.3338$, $b = 0.32164$, $c = 0.94686$, I believe the correct answer is approximately $0.009803$. I found this through simulation.  I would appreciate any help or suggestions.


Does the everywhere differentiability of $f$ imply it is absolutely continuous on a compact interval?

Suppose $f$ is differentiable everywhere on $[0,1]$. Must $f$ be absolutely continuous on $[0,1]$? I know this is true if $f'$ is integrable but I'm not sure in this more general case.


Suppose $T:V\to V$ is a diagonalizable linear transformation with no repeated eigenvalues, and denote $\{e_i:i\in I\}$ an eigenbasis of $V$. Suppose $W$ is an invariant subspace of $T$. Is it true that $W=span\{e_i:J\subset I\}$ for some $J$? Why?


Why does String not require a constructor in Java?

In Java programming, despite String being a reference variable and not a primitive, a constructor is not required, e.g  String s = "stringValue";  Is the same as   String s = new String("stringValue");  I've seen it mentioned before, but never explained. How is String treated as a primitive, and is this functionality able to built into other classes?  Edit: Looking for the actual code that makes String different, and how it can be used - not like in the specific example supplied.


I have created a form which has only a submit button. In the submit function I am generating csv file and saving it to the files folder using fputcsv function.  But Now I need extra functionality of submit. After saving the file it should download the file also.  How to do this? Any one have some idea about this?


why the result of this function not assigning value of 1

why the result of this function is not 1?       function call(t) {     t = 1; };  var b = 0;  call(b);  console.log(b)


ogr2ogr getting ESRI File Geodatabase (FileGDB) work

I'm using ogr2ogr to load ESRI .gdb into PostGIS DB. I'd also like to export to .gdb the other way round.  But the included OpenFileGDB driver only has read access.  Now there are hints to use ESRI's  but I cannot get it work. What do I have to copy and where or what are the steps to get it work?  EDIT: It's MS 10 and GDAL 2.1.3. Installed it via OSGeo4W64.


When I use a vector within the text, the vector appears too big - how can I make it smaller?  Example:  \documentclass[12pt]{scrartcl} \usepackage{amsmath} \usepackage{amssymb} \begin{document} One standard basis vectors of $\mathbb{R}^2$ is \begin{pmatrix}1\\0\end{pmatrix}$.  Unfortunately, the vector is about twice as tall as the rest of the line.  How can I reduce its size to about $1.5$-times the size of the line? \end{document}


How can I make an app keyboard shortcut override the global default?

For instance, Ctrl-Space is a commonly accepted "code completion" shortcut in several IDEs (IntelliJ IDEA etc.), however on the system level it is "change input source (language)" shortcut. I don't need other languages while in IDEA, so can I have Ctrl-Space trigger code completion in IDEA without changing the global default?  PS: I know about  but the solution there is to change the global default (which I don't want to do).


Motion tracked Video doesn't show up in the render or in the compositing tab

I tried to add a 3D object to a clip by following a youtube video. But clip doesn't show up in the render or in the compositing tab. It show up even in the camera view. I didn't change any settings. please help. Thank you.    And the  rendered images has only the cube in it like in the picture above.


Structs and Classes / value type vs refrence type

So I've been trying to get my head around this for weeks.  I understand that structs are value types, and that classes are reference types.  Where I get confused is the differences in behavior between the two.  For example: If I have a bag of potatoes, and each potato is a different size, shape, and weight... The bag would be a 'class' / reference type The potatoes would be a 'struct' / value type  Can my potatoes be a class, or do they have to be a struct as the values contained within are different?  Basically, the answer to that question will clear everything up for me.  Thank you!


iPhone 6s stuck in DFU mode after downgrading

I'm trying to downgrade from iOS 11 beta 2 back to iOS 10.3.2. I've downloaded the .ipsw from iOS 10.3.2 file from ipsw.me. After that, I've put my iPhone in DFU mode and plugged into my Mac (Sierra 10.12.5). iTunes detected the phone in DFU mode, so then I choose the restore option holding option key and selected the .ipsw file downloaded. The iTunes pass through all process of restoring the phone, but right after it ends, the iPhone restart and go back to the DFU mode. I've tried to download the 10.3.1 ipsw version but the same problem occurred. I've no idea how to proceed.


The most common way to refer to non-immediate family?

Example:     When my mother came back from the island, she came back as a newborn Christian. [...]   was shocked, especially since none of them belonged to that religion.   (In this case, they refer to the mother's parents/brothers/sisters, and also the husband's parents/brothers/sisters. Not the husband because he was dead. And not the speaker because he was still a baby. So there's no immediate family.)  What would a native English speaker use in cases like this? Her family, my family, our family, or my relatives?


How to interpret the R2 in univariate regression analysis?

How to interpret the R2 in univariate regression analysis ?


What is the Stack Exchange site for asking about finance-related terminology?

Where can I find a Stack Exchange network to discuss finance terminology and questions like:     What is the right term for an investor loan account that is near maturity?


how to check for null or undefined in Javascript for an ID

I have a situation to check if a LINK made of "a href" is hidden or not. All good.  But we use same javascript in many other pages. So some pages might not have this element (I mean ID). How do I make a null or undefined check so that it doesn't through null error when it evaluates below if condition.  I want to check for this specific ID "AgeCheckbox". The way we usually check for null in C# and then evaluate condition. Please help me.   function Handle(err) {     if ($('#AgeCheckbox').is(":hidden") == false)     {         CalMedicine();         ShowTotal();     }    }   I read some articles, I want it to be strong, using 3 equals or so.


What is the difference between "I'm in no mood " and "I was in no mood"? I asked my mentor and he told me they're both the same, but I see that these are different in regards to tense.


I'd like to have normals spaces in a specific frame. Or, i've got some huge and hugly spaces. Here is a picture.    I've tried [t, allowframebreaks=.70] without succes. Here is my code.  \documentclass[c]{beamer} \usepackage[latin1]{inputenc} \usepackage[T1]{fontenc} \usepackage[french]{babel} \setbeamertemplate{frametitle continuation}{}  \begin{document} \begin{frame}[allowframebreaks=.70] \frametitle{Plan} \tableofcontents \end{frame}     \section{a} \begin{frame} aaa \end{frame} \section{b} \begin{frame} bbb \end{frame} \section{c} \begin{frame} ccc \end{frame} \section{d} \begin{frame} ddd \end{frame} \section{e} \begin{frame} eee \end{frame} \section{f} \begin{frame} fff \end{frame} \section{g} \begin{frame} ggg \end{frame} \section{h} \begin{frame} hhh \end{frame} \section{i} \begin{frame} iii \end{frame} \section{j} \begin{frame} jjj \end{frame} \section{k} \begin{frame} kkk \end{frame} \section{l} \begin{frame} lll \end{frame} \section{m} \begin{frame} mmm \end{frame} \section{n} \begin{frame} nnn \end{frame} \section{o} \begin{frame} ooo \end{frame} \section{p} \begin{frame} ppp \end{frame} \end{document}


Lie algebras are known as non-associative structures.   My question is that do we have any example of Lie algebras which is associative?  Many thanks!


Combinatorics problem involving selection of digits

How many 10-digit decimal sequences using $(0, 1, 2, . . . , 9)$ are there in which digits 3, 4, 5, 6 all appear?  What I did to solve this question was this.   The number of ways to select $3,4,5,6$ from $10$ numbers is   $$\binom{10}{4}$$  and the ways to fill the rest of the digits would be $10^{10-4}=10^{6}$  So I thought that the total number of possibilities would   $$\binom{10}{4}*10^{6}$$  I was wondering what is wrong with this reasoning?   The answer that you get using inclusion-exclusion principle is different.


Database suitable for storing annotations?

I am a novice in database administration and have a design question. My use-case is storing data annotations(data labels) for Machine Learning, which can run into hundreds of thousands for each client. I will also need to query based on information within those annotations. Would I be better off using a NoSQL database like MongoDB, or a relational one like PostgreSQL, where I can save each annotation as a json? In case of a relational database, would it make sense to save each client's annotations in separate tables? PS - I also need to store other data that is usually stored in relational databases, like users, tasks etc.


This is my curl script  #!/bin/bash  PING_STATUS="$(netcat -vz mc.bella.wtf 25565 2>&1)" curl -H "Content-Type: application/json" -X POST -d '{"embeds": [{"title": "Server Status:","color": 16027903,"description": "'"$PING_STATUS"'"}]}' "$WEBHOOK"   This is what I get when I run my crontab:  mc@ubuntu:~$ crontab -l * * * * * /home/mc/server/ping >/tmp/mycommand.log 2>&1 mc@ubuntu:~$ cat /tmp/mycommand.log  curl: (3) <url> malformed   Why is my url malformed when it works fine when running the script by itself?


proving that -1 is square if p = 1 mod 4

I have to find $gcd(x^{P-1}-1,x^2+1)$ in $\Bbb{Z}/p\Bbb{Z}[X]$ for some prime number p in order to show that $-1$ is a square $\pmod p$ iff $p\equiv1\pmod4$. I really have no idea where to start. I don't see how to get the gcd given that p is not a number. Any help would be appreciated.  Thanks


Write a query to display the student names and the maximum mark scored by them in any subject, ordered by name in ascending order. Give an alias to the maximum mark as MAX_MARK. I am not able to find the logic for this. Kindly help me with it. Do it in oracle SQL I am at beginner level in SQL. SELECT MAX(M.VALUE), S2.SUBJECT_ID,M.STUDENT_ID, S2.SUBJECT_NAME,S2.SUBJECT_CODE from Mark M INNER JOIN SUBJECT S2  ON M.SUBJECT_ID=S2.SUBJECT_ID group BY S2.SUBJECT_ID,  S2.SUBJECT_CODE, S2.SUBJECT_NAME;  I am getting error with this query if I get this student id with the help of the above query then I can easily solve this question using subquery concept.


Is there a specific word for someone who dies, not at birth, but years later, ON their birthday? An historical person who comes to mind would be inventor John Harrison, who was born  March 24, 1693, and died on his birthday,  March 24, 1774.  What would you call this event or person, other than deceased? Is there a special name for dying on one's birthday?   The reason my question may be different is because the answers given to the 1st question seemed to not be answering the question asked because of a misunderstanding of the nature of the question.  People kept answering about babies miscarried or stillborn on their date of birth, not birthday. I am attempting to clarify the responses given by rephrasing the question into something clearer that will bring about the answer asked originally asked for.


Update: They fixed the macOS wifi lag on Synergy 1.9.0!   I’m using  and using a Windows 7-Desktop as the server and a Kubuntu-Laptop as client.  My laptop is connected to my router via WLAN and my desktop is connected via cable. I have no idea what to do since it worked fine first, but for a couple of weeks now the mouse and keyboard are unbearably laggy on the client, to the point where I can barely use them.


Do you ever use the phrase 'good for you' with a completely positive connotation?

I feel the phrase 'good for you' shows a sense of detachment or lack of interest and sounds so rude while the phrase 'I feel happy for you' shows a sense of interest and friendship. I wonder why would anyone use 'good for you' versus other simple phrases unless they want to point out that they could be happy for us but they don't care much anyways. Do you use the phrase even when you genuinely care about the person you are saying it to ?


Examples of topologies in which all open sets are regular?

An open subset U of a space X is regular if it equals the interior of its closure, as we learn from the Wikipedia . Furthermore, the regular open subsets of a space (any space) form a complete Boolean algebra.  I'm coming to this from logic and algebra, with not much background in topology. I can't figure out which topologies have "interesting" collections of regular open sets. For example, in the trivial topology and the discrete topology, every open set is regular, if I'm not mistaken. Those are not "interesting" topologies. I assume there are other topologies in which the space X and the null set are the only regular open sets. If so, those aren't "interesting" either, at least not with regard to their regular open ets.  I believe what I'm looking for is topologies in which every open set is regular, other than the ones I've just described.  Thanks for any help.


I'm new to Ubuntu and Ganache and do not know how to open a terminal in this software.  Can anyone provide instructions on how to open a terminal in Ubuntu and/or Ganache?


Can I use 72 dpi images in stand-up banner for print?

Will it be appropriate printed quality if use images at original size with resolution 72 dpi in banner 80 cm x 200 cm?


Build c# Generic Type definition at runtime

At present I'm having to do something like this to build a Type definition at runtime to pass to my IOC to resolve. Simplified:  Type t = Type.GetType( "System.Collections.Generic.List`1[[ConsoleApplication2.Program+Person");   I know the generic type argument at runtime only.   Is there something that will allow me to do something like this (fake code):  Type t = Type.GetTypeWithGenericTypeArguments(     typeof(List)     , passInType.GetType());   Or shall I just stick to my hack, passInType.GetType() convert to string, build generic type string.. feel dirty


A surjective homomorphism between finite free modules of the same rank

I know a proof of the following theorem using determinants. For some reason, I'd like to know a proof without using them.     Theorem   Let $A$ be a commutative ring.   Let $E$ and $F$ be finite free modules of the same rank over $A$.   Let $f:E → F$ be a surjective $A$-homomorphism.   Then $f$ is an isomorphism.


What proportion of salt in water would make it not dehydrate nor hydrate someone?

Drinking sea water can be deadly as it contains too much salt, basically de-hydrating the body. Normal tap water contains little salt and is good for re-hydration. My question: How much salt needs to be dissolved in water such that it does not hydrate nor de-hydrate? For instance, would a physiologic saline solution (9 grams of salt per liter of water) meet this criterion?


Can the charge of $d$, $s$ and $b$ quarks be thought of as unitary charge? The electron is considered as an elementary particle but nevertheless has three times more charge than any of these three quarks. Is the ratio of electron and one of these quarks the whole number three or are there measurements that show that some decimals are not zero...e.g. 3,0000001245? If all the decimals are zero is this just a coincidence?


How does one avoid the "staircase effect" in pixel art motion?

I am rendering sprites at exact pixel coordinates to avoid the blurring effect caused by antialiasing (the sprites are pixel-art and would look awful if filtered). However, since the movement of the objects involves variable velocity, gravity, and physical interactions, the trajectory is computed with subpixel precision.  At large enough screenspace velocities (vΔt larger than 2 or 3 pixels) this works very well. However, when velocity is small, a noticeable staircase effect can appear, especially along diagonal lines. This is no longer a problem at very slow screenspace velocities (v << 1 pixel per second) so I am only looking for a solution for intermediate velocity values.  On the left is the plotted trajectory for a large velocity, obtained by simple rounding of the object coordinates. In the middle you can see what happens when velocity becomes smaller, and the staircase effect I am talking about. On the right, the locus of the trajectory I would like to get.    I am interested in algorithm ideas to filter the trajectory in order to minimise the aliasing, while retaining the original behaviour at large and small velocities. I have access to Δt, instant position and velocity, as well as an arbitrary number of previous values, but since it is a realtime simulation, I do not know about future values (though if necessary, an estimation could be extrapolated under certain assumptions). Note that because of the physics simulation, sudden direction changes can also happen.


Let f be a function such that $|f(x)| \leq x^2$ for all x. Prove f is differentiable at 0.

This question is straight from Spivak Chapter 9, Question 15. I have attempted the previous problem, which is another differentiable function I had to prove.  I want to attempt this problem using the definition of a derivative as a limit. The issue in this problem for me is the $\leq$ sign. How do you work with this restriction? Any hints are appreciated.  Surely I can take $f$ to be $x^2$ since this satisfies the condition that $|f(x)| \leq x^2$? Is this sufficient to prove the condition?     Proof. Let a function $f$ be defined as $|f(x)| < x^2$. Since $x^2$ is such a function, we know that the derivative of $x^2 = 2a$, and since $x^2$ is differentiable at 0, the (half-assed) proof is complete.   I have skipped many steps in the proof. I merely asserted that $x^2$ is differentiable at 0 and meets the restriction specified.


Spoiler Markdown shows up as normal blockquote

In the question , I used the >! syntax to create a spoiler section, but it shows up as a normal blockquote with a ! at its start.


Im a beginner and am following a tutorial for a donut, im at the point where i am trying to render it but i must have clicked something or done something wrong as my object no longer shows up in the render view when i click Z and switch. If i select all before going into the render mode i can see the outlines are there just not the object. If anyone could help it would be appreciated.


Show that if $\sum_{n=1}^{\infty}a_n^2$ converges, then $\sum_{n=1}^{\infty}{a_n \over n}$ converges absolutely

I am trying to show that if the series $\sum_\limits{n=1}^{\infty}a_n^2$ converges, then the series $\sum_\limits{n=1}^{\infty}{a_n \over n}$ converges absolutely. How might I approach this?


What is the best book to learn probability?

Question is quite straight... I'm not very good in this subject but need to understand at a good level.


Just installed Lubuntu and it doesn't show my disks (D:\, E:\ and ...). What can I do?

I've just installed Lubuntu 17.10 on my laptop and removed Windows 7. But I can't find my former hard disks (D:\, E:). When I tried Lubuntu without installing ( and deleting the previous os ) I could use my hard disks. But they have disappeared. What can I do?


How do i convert from LaTeX, to XeLaTeX for better Unicode listings

I have these as my LaTeX Code:  \usepackage{geometry} % Packet für Seitenrandabständex und Einstellung für Seitenränder \usepackage[ngerman]{babel} % deutsche Silbentrennung  \usepackage{booktabs} %entzerrt die Tabellenzeilen und bietet verschieden dicke Unterteilungslinien \usepackage{longtable} % Tabellen können sich nicht über mehrere Seiten  \usepackage{graphicx} % kann LaTeX Grafiken einbinden  \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} % Zeichenencoding \usepackage{lmodern} % typographische Qualität  \frenchspacing % Schaltet den zusätzlichen Zwischenraum ab \usepackage{fix-cm} \usepackage{hyperref} % verwandelt alle Kapitelüberschriften, Verweise aufs Literaturverzeichnis und andere Querverweise in PDF-Hyperlinks \usepackage{color} \usepackage{url} \usepackage[nottoc]{tocbibind}   It compiles, but i want to use the latest xetex versions of my template.


I have always argued adamantly, as long as the issue has been around, that gift should never be used as a verb. However, someone whose English knowledge I quite respect disagrees.  I’ve done some searching and I haven’t found a consensus; should gifting be shunned?


I don't get the concept of "God plays with dice" - In what scenario is it proven that he does?

I am no physicists, but I don't get the concept of God playing with dice. Logic shows me that the entire universe is calculated very precisely according to the correct (far more than we know) formulas of physics.   I think that if the universe were to restart today from nothing as an exact replica of it's original origin under the exact same conditions, when the time reached the universe's current age, I would be sitting here again typing up this question.  But if God does indeed play with dice, then this has to be false. It would mean that there are random factors in physics. I'm inclined at this point to believe that any "random" factor in Quantum Physics is simply a factor that hasn't been understood by physicists yet. After all, we're always wrong about something in science.   My question:  In what scenario have physicists observed a truly random factor in quantum physics?     While I was asking for a specific scenario that proves random factors exist in physics, a comment below explained the concept rather nicely, albeit without proving an observable scenario:     I believe that it is accurate to state that if 1) quantum mechanics is   true (as it appears to be; the evidence for it to be right is said to   be overwhelming) and 2) there are indeed hidden variables or many   universes, then 3) "we" in principle cannot and will not (ever) have   access to those variables or other universes. Depending on taste you   may still consider that indeterministic, as in: in principle (because   of QM) unknowable and unpredictable (if even existent) to physicists.   –  Glen The Udderboat


I have date in string:  mystring = "2013-10-25 07:53:07.367857"   Can I convert this string to datetime object?


How to run a website domain without redirecting if IP is already used for another website?

I bought a VPS Host that gave me only 1 IP Address which I used on my first domain name and it works without any problems.  Now my second domain name I can't use the same ip address as it points to the first domain name.  So I figured my only option was to use a GoDaddy hosted iframe redirection which redirects to a sub folder on my first domain which worked so far.  Now I'm trying to load paypal from <?php headers() ?> and I get a permission error because of that iframe  Refused to display 'https://www.paypal.com/cgi-bin/webscr?notify_url=&cmd=_cart&upload=1&business=removed&address_override=1' in a frame because it set 'X-Frame-Options' to 'SAMEORIGIN'.   How do I avoid the Iframe solution for my second domain while not messing up my first domain?  Somebody I forgot once told me it doesn't matter if you have 1 IP Address you could host multiple websites on it? how it that possible the DNS doesn't seem to work off ports afaik, yes I could host multiple websites on different folders but that's not what I call hosting a real website it has to be pointed by a domain name, so this iframe issue doesn't happen  My server configuration is httpd (apache) that comes with CentOS 6 (Linux) operating system


What is the best way to iterate over a dictionary?

I've seen a few different ways to iterate over a dictionary in C#.  Is there a standard way?


How to make an Executable ".exe" file from a java Code

I have an application that works fine and that I can execute from a .jar file. But I want to know how to make it runnable from any computer even if there is no JRE or the JRE version is not the good one. I thought about a .exe file but don't know how to do it. I made my code with Eclipse and it use jxl,jdom and jfx librairies. I tried to use Inno Setup 5.5.6 but when in Eclipse I run my build.xml as Ant Build it return me an error that says :   "'Launching JFX Build - Myapp' has encountered a problem.   The achive : C:/Program%20Files/eclipse/plugins/org.eclipse.swt.win32.win32.x86_64_3.104.0.v20150528.jar which is referenced by classpath, does not exist."


How is the Jedi mind trick not a dark side technique?

How is the Jedi Mind Trick not a Dark Side technique? Isn't tricking another person's mind unethical? How can the Jedi use it and not become Dark?


Proof of ${n \choose 0},{n \choose 1},{n \choose 2},...,{n \choose \lfloor n/2\rfloor}$ is monotonically increasing

Prove that for $n>1$, sequence $${n \choose 0},{n \choose 1},{n \choose 2},...,{n \choose \lfloor n/2\rfloor}$$ is strictly monotonically increasing.  If I will show, that $${n \choose \lfloor n/2\rfloor}-{n \choose \lfloor n/2-1\rfloor} >0$$ will that  be the end of proof?


TL;DR Is there a way under Linux to know which file access caused an hard disk to   spin up?   Full story My laptop has a NVME disk, which contains the operating system and my home dir, and a spinning hard disk, which contains a second home dir which I use to store bulk data that do not fit on the NVME. I believe it is a common arrangement.  One of the nice things is this layout is that when I am not working on the projects that require files on the spinning disk, the disk itself can spin down, saving on energy, battery time, noise, etc. And this happens quite frequently.  However, every now and then the hard disk spins up even if what I am doing in that moment has no clear link with data that are stored there. It is still a consequence of an action done by me, not of a cron script or something else, because it still happens as a consequence of my doing something, like opening an application. However I cannot see what opening that application should produce an access to the spinning disk, knowing which file are supposed to be there. So I would like to understand more of what happens, and this justifies the question above.


Does anybody see such an array indexing way like "2[array]"?

Today, I see such a wierd way of indexing the arry.  The code is like:  int array[] = {10, 20, 30}; cout << -2[array];   I've never seen such a strange way of using array. But there is no compilation error.  Can anyone tell me does the ISO document evolve the description for this way of using array?


I want to prove the following: $$\sum_{k=1}^{n}k\binom{n}{k}=n\cdot2^{n-1}$$ what I did is(use binominal): $$\binom{n}{k}X^k\cdot 1^{n-k} = (X+1)^n$$ $$k\binom{n}{k}X^k\cdot 1^{n-k} = k(X+1)^k-1$$ now I replace $k$ by $n$ and insert $X=1$ , I will get now $n\cdot2^{n-1}$ what you are suggesting? there is another way to do that? thanks!


when wanting to inform someone of some future event, in which way would you say it, and what are the differences, if any?   (you will) be notified (...) (you will) get notified (...)


I am trying to follow  to allow other users to access my ext drives. Except I need to use my own username, and I just don't know what that is. I thought it would be the name I gave to my own Ubuntu account, but apparently is not.


My website pages not getting indexed by Google

The website www.itztechgadget.com isn't getting indexed at all.  When I check about it in Websmater Tools, it shows 0 pages indexed. I'm not getting why is this problem happening. Googlebot fetches and submits it to be indexed but none of website's pages are indexed.


For , the answer given on 7 Feb about how to edit the subject line in the new format of Gmail does not work for me.   There is no box on the left with a down arrow to options to reply, forward or edit subject in my version. There is a book on the right offering options to    Reply Reply to all Forward Filter message Print Delete Report spam Report phising Show original Message text garbled Translate message Mark answered    But, no option to edit subject


2s orbital wavefunction has non-zero probability at $r=0$?

The wavefunction for an electron within a hydrogen atom in the $2s$ state has the following wavefunction:  $$\psi(r,\phi,\theta)=\psi(r)=\frac{1}{2\sqrt{\pi}}\left(2-\frac{r}{a_0}\right)\frac{e^{-r/2a_0}}{(2a_0)^{3/2}}$$  However, at $r=0$,   $$\psi^*\psi\left.\right|_{r=0}=\left(\frac{1}{2\sqrt{\pi}}\left(2-\frac{0}{a_0}\right)\frac{e^{-0/2a_0}}{(2a_0)^{3/2}}\right)^2=\frac{1}{\pi(2a_0)^{3}}$$  I don't understand how this should be possible. My answer doesn't match logic and it doesn't match graphs that I find online. (every graph I see goes to zero at $r=0$)     However, this does seem to really be the wavefunction for the 2s state.  Where have I gone wrong?


Why do quantum effects dominates when the thermal de Broglie wavelength is on the order of or larger than the interparticle distance?

We say that when the thermal de Broglie wavelength is much smaller than the interparticle distance, the gas can be considered to be a classical or Maxwell–Boltzmann gas. On the other hand, when the thermal de Broglie wavelength is on the order of or larger than the interparticle distance, quantum effects will dominate and the gas must be treated as a Fermi gas or a Bose gas, depending on the nature of the gas particles.  $(V/N)^{1/3} < \lambda_{th} $. My question is why do quantum effects dominate?


If I use red eyes dmd effect to bring a dragon from the graveyard then send red eyes dmd to the graveyard and then bring it back in the same turn, is it treated as a new monster resetting it so I can re-use its effect to special summon another monster?


CSS : wondering what does "\" mean in CSS

I'm trying to make dropdown menu with tailwindCSS   and there is a good example for me :   but i can't recognize where is a hover control, and what is \ mean in CSS.  hope kindly help me.  .group:hover .group-hover\:block {   display: block !important; }


Is it possible to pass arguments into event bindings?

I haven't found an answer elsewhere and this doesn't appear to have been asked yet on SO.  When creating an event binding in wxPython, is it possible to pass additional arguments to the event? For example, this is the normal way:  b = wx.Button(self, 10, "Default Button", (20, 20))         self.Bind(wx.EVT_BUTTON, self.OnClick, b) def OnClick(self, event):         self.log.write("Click! (%d)\n" % event.GetId())   But is it possible to have another argument passed to the method? Such that the method can tell if more than one widget is calling it but still return the same value?   It would greatly reduce copy & pasting the same code but with different callers.


How much do Muggle parents like Hermione’s actually know about Hogwarts?

This is left vague in the books, but I can’t imagine parents sending their children off to a school they know nothing about. Do you think they’re well-informed, or told just a bare minimum, or are they outright lied to?


Why are derivatives in interaction terms treated differently from derivatives in the kinetic term?

I know that derivative couplings in a Lagrangian interaction, such as   $$\mathcal{L}_{int} = \lambda \phi (\partial_{\mu}\phi)(\partial^{\mu}\phi)$$  bring down two momentum factors into the matrix element $\mathcal{M}$.   Why doesn't this extend to a typical kinetic term  $$\mathcal{L}_{kin} = (\partial_{\mu}\phi)(\partial^{\mu}\phi)\quad ?$$  It seems odd that derivatives in $\mathcal{L}_{int}$ contribute a factor of momentum$^2$ to $\mathcal{M}$, but the derivatives in $\mathcal{L}_{kin}$ contribute a factor of the propagator $$\frac{1}{\mbox{momentum}^2}$$  to $\mathcal{M}$.


When wouldn't I use LASSO for model selection?

Assume that you need to build a linear model to make predictions for new observations, and that there is uncertainty about which subset of variables should be included in the model. You are only interested in making predictions, there is no theory available to guide variable selection, and you aren't interested in drawing causal inferences.   In this scenario, when wouldn't you use LASSO? Everything I read makes it sound like the perfect tool in this situation. However, when I have a nice new hammer in my hand, all problems look like nails, so I would like some examples of reasonable scenarios where variable selection and avoiding overfit are important, but when LASSO is either entirely inappropriate, or unlikely to be the best option. There are other threads on why you should use LASSO; I want to know why I shouldn't.


How can I show a leading + sign in siunitx S column?

I'm using siunitx's S columntype to align numbers in a table. The numbers are percentage values which should all have a preceding sign (some - and some +).  The numbers with a "-" are shown with a sign, the "+" sign vanishes as siunitx processes the numbers.   How can I keep the sign of the numbers including the "+" sign?


Utilizing a single core to 100% doesn't show in perf mon as single cpu being fully utilized

Ever since Windows 2008 I've noticed the following behavior:  I'm using a windows 2008R2 VM with two vCPUs but this also works on a physical server. I'm using SQL server 2008 R2 for this example.  Make sure you have processor affinity set to AUTO (the default):  ALTER SERVER CONFIGURATION SET PROCESS AFFINITY NUMANODE = 0   (takes affect immediately)  Run a query that will utilize a single core at 100%:  DECLARE @c INTEGER  WHILE 1=1 BEGIN     SET @c=@c+1 END   Now, open Windows Performance Monitor and add the counters:   Processor: % Processor time _Total  Processor: % Processor time 0 Processor: % Processor time 1   In my pictures, _Total is highlighted (black) and both seperate CPUs are red and green.  What I would expect to see is, one of the cores at 100%, another near 0% and the _Total around 50%.  But instead I get this:    It seems as if the Windows OS Scheduler tries to divide the load across both cores by alternating the task between cores.    Set the processor affinity explicitly to use all cores. From a SQL cpu perpective everything is still the same. SQL Server still has goth both vCPUs are both usable.  ALTER SERVER CONFIGURATION SET PROCESS AFFINITY NUMANODE = 0   When I run the same query I get the graph that I was expecting:    For the most part of the time, the task is running on one core only. In this case the green one.   This last graph is basically how it was in pre windows 2008.  Questions:   What's happening under the hood in the first scenario? Why is this behaviour changed once I explicitly tell SQL Server that my processor affinity is to use all cores. Instead of leaving it on auto. In the old days it was very easy to spot a query that was limited by a single core by opening up perf mon and look at all separate cores and find one that was utilized at 100%. Any alternatives to do that now?


I have a file named diario.sh that I run manually using ./diario.sh The script file contains the following: #!/bin/bash cd /home/etapa/Scripts echo "@CDRS_ETAPATOTAL.sql" | sqlplus -s ooperadores/ooperadores@OOPERADORES | while read output; do echo $output done  When I run it manually works fine but when I try to run it using crontab I get the following error: ERROR: ORA-12154: TNS:could not resolve the connect identifier specified   SP2-0306: Invalid option. Usage: CONN[ECT] [{logon|/|proxy} [AS {SYSDBA|SYSOPER|SYSASM|SYSBACKUP|SYSDG|SYSKM|SYSRAC}] [edition=value]] where <logon> ::= <username>[/<password>][@<connect_identifier>] <proxy> ::= <proxyuser>[<username>][/<password>][@<connect_identifier>]  ERROR: ORA-12162: TNS:net service name is incorrectly specified   SP2-0157: unable to CONNECT to ORACLE after 3 attempts, exiting SQL*Plus  The crontab entry is the following: 10 * * * * /home/etapa/Scripts/diario.sh > /home/etapa/Scripts/diario.log 2>&1  Please help me solve this problem.


Prove $\sum_{i=1}^{2^n} \frac{1}{i}\geq 1+\frac{n}{2}$ for any $n\in\mathbb{N}$. I believe proof by induction is best way, but I am not sure best way to show this from the inductive step. Thanks.


How would you write the possessive with yourself and another person?  For example:     Would you like to join Bob's and my group?


4 cards are drawn from a pack without replacement. What is the probability of getting all 4 from different suits?  Here's how I tried to solve:  For the first draw, we have 52 cards, and we have to pick one suit. So, probability for this is $\frac{13}{52}$.  For the second draw, only 51 cards are left. The second suit has to be selected, so there are 13 cards from that suit. The probability is $\frac{13}{51}$.  Similarly, the third and fourth draw have probabilities $\frac{13}{50}$ and $\frac{13}{49}$ respectively.  Since the draws are independent, the total probability becomes $$\frac{13}{52} \times \frac{13}{51} \times \frac{13}{50} \times \frac{13}{49}$$  But my book says the answer is $\frac{{13\choose 1} \times {13 \choose 1} \times {13\choose1} \times {13\choose1}}{52 \choose 4}$.  My answer differs by a factor of $4!$. What did I do wrong?


how can I extrude curve shapes onto curve without tapering

I'm stuck. Can't figure out how I can extrude a closed curve onto a NURBS curve without it looking tapered.   I notice that when it's set to "2D" there is no tapering, but I want to do it on 3d.  Thanks for help.


I've a Sumsung series 5 laptop with 4GB ram dual booted with Windows 10 and Ubuntu 16.04 LTS. My brightness does not work although the "function key+brightness button" shows the indication that it is being changed but brightness just does not really change. It works fine on Windows 10.  I tried sudo gedit /usr/share/X11/xorg.conf.d/20-intel.conf      Section "Device"             Identifier  "card0"             Driver      "intel"             Option      "Backlight"  "intel_backlight"             BusID       "PCI:0:2:0"     EndSection   Also,  sudo gedit /etc/default/grub  GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" to  GRUB_CMDLINE_LINUX_DEFAULT="quiet splash video.use_native_backlight=1"   Still the problem is there  please help


The police have three suspects for the number of Mr. Boddy: Professor Plum, Colonel Mustard, and Mr. Green. Professor Plum, Colonel Mustard, and Green each declare that they did not kill Boddy. Mustard also states that he did not know Boddy and that he was out of town the day Boddy was killed. Green also states that he saw both Plum and Mustard with Boddy the day of the killing and that either Plum or Mustard must have killed him.  Assume one of the three men is guilty and that innocent men do not lie. The statements of the guilty man may or may not be true. Determine who killed Mr. Boddy and prove it.


Distribution of the combination of two Chi-squared distributions

The random variable $A$ has a $\chi^2$ distribution with $p$ degrees of freedom. The random variable $B$ is independent of $A$ and has a $\chi^2$ distribution with $q$ degrees of freedom. Show that $(A+B)$ and $(A/(A+B))$ are independent and determine their distribution. So far I worked out that: $(A+B)$ will have a $\chi^2$ distribution with $(p+q)$ degrees of freedom. $(A/(A+B))$ is a division of two $\chi^2$ distributions, which is pretty close to an F-distribution. I cant figure out how to get their distributions and show the independence.


Given $a_1=1, a_2=2, a_{n+1}=n(a_n+a_{n-1})$ find the general term

Given recursively defined sequence $(a_n)$: $$a_1=1$$ $$a_2=2$$ $$a_{n+1}=n(a_n+a_{n-1}), n\geq 2$$  Find the formula for the general term $a_n$.   This is what I did:  So the first few terms are: $a_1=1, a_2=2,a_3=6,a_4=24,a_5=120,...$  I guess the general term can be written as $n!$. Let's prove it by mathematical induction:   Base case: $a_1=1!=1$ so it's true for $n=1$. Let's assume it's true for some $n$,i.e. $a_n=n!$. Then $$a_{n+1}=n(a_n+a_{n-1})=n(n!+(n-1)!)=n(n(n-1)!+(n-1)!)=n(n-1)!(n+1)=(n+1)n(n-1)!=(n+1)!$$  Using the principle of mathematical induction we've proved that the general term of this sequence is $n!$.  Is this proof valid? I'm not sure whether it's allowed to put $a_{n-1}=(n-1)!$ here.


Checking style.width with Javascript IF statement

i need to check style.width with an js if statement. But it is not working. How can i do that? My if code: if (document.getElementById("XXX").style.width == "100%") {  }


What is the LaTeX manual and how can I see a particular page of it?

Any of us, especially me, usually get error messages like:   ! LaTeX Error: Command \c@XXX already defined.                Or name \end... illegal, see p.192 of the manual.  See the LaTeX manual or LaTeX Companion for explanation.   Where is the LaTeX Manual the error is talking about!?  How can I have a look at p. 192, of the named Manual?   I am using XeTeX came with TeXLive 2013, on an Ubuntu 14.04LTS.  My question is:  Isn't better to make a copy of the manual available to all! Just takes few more MegaBytes comparing to a GigaByte distribution is nothing!  At least refer us to a publicly available reference instead of a commercial (of course very valuable but also many parts of almost out dated) book.


Searching deleted posts in the Android app

I would like to know how users with 1k reputation can search deleted posts. I don't think they will be searchable through the regular search icon at the top of the Android app, but I don't know.


Actually, I don't know how to explain this question in a proper title. Any edition is welcome.  Let's just see the example.  # python 2.7.x import collections d = collections.defaultdict(int) d['a'] = 2 d['b'] = 1 res = [d]* 2 res[0]['a'] -= 1 print res[1] # => defaultdict(<type 'int'>, {'a': 1, 'b': 1})   I was wondering why it affects the res[1]?


I'm trying to use a method within a Python program to detect whether a file on the file system has been modified.  I know that I could have something run on an every-5-seconds to check the last modification date off of the system, but I was curious as to whether there's an easier method for doing this, without needing to require my program to check repeatedly.  Does anyone know of such a method?


I'm developing an RPG/roguelike-style game. Instead of having maps like:  ......... ......... ....@.... ...h.....   Oh look, a dwarf.  I was having solid background tiles, So sort of a tile based RPG without drawn tiles. I like the idea of having ascii tiles for creatures and things. It saves a lot of artist time. I can change the tiles so I get some kind of symbol slightly more...related? But better than having 4 directions for each separate thing.  If I did this in white, and had a snow area, you wouldn't be able to see. So make it black. As soon as you reach a dark place, you're again stuck as to where your character is. Is there an algorithm or something that can say 'this is too dark between the tile and the NPC' and change the colour to something seeable, but not going to a bright cyan from a pale pink or whatever?


What I want to do is make a dictionary of all the tickers on AMEX, NYSE and NASDAQ markets and their associated names/shortened names. I have all the information I need in Excel, I just don't know how to transfer it into C#.  I am going to be using the dictionary to test user input.  Right now I am using an SQL database and the only input that works for searching for a company like Apple, is either its associated stock ticker AAPL or typing the full name of the company like Apple Inc..  This is my dictionary setup, I have it in its own .cs file:  public class FinancialTickers     {         public string AssociatedName { get; set; }         public string CompanyName { get; set; }     }      public static void Main()     {      }


The acceleration vector of a simple pendulum

In this picture the acceleration vector $\vec{a}$ points upward when the pendulum is halfway    But according to this picture, the force acts tangentially:    Which means the acceleration should be tangential too, and never pointing upward?  So whats right?


How to prove that $W^n_p[0,1]$ is a Banach space?

Problem. Let $1\le p<\infty$ and $n \ge 1$ and let $W^n_p[0,1]=$ the functions $f:[0,1]\to \Bbb{C}$ such that $f$ has $n-1$ continuous derivatives, $f^{(n-1)}$ is absolutely continuous, and $f^{(n)} \in L^p[0,1]$. For $f$ in $W^n_p[0,1]$, define $$||f||:=\sum_{k=0}^n\left[\int_0^1|f^{(k)}(x)|^p ~\mathrm{d}x\right]^\frac{1}{p}$$ Then $W^n_p[0,1]$ is a Banach space.  If we take a Cauchy sequence $(f_j)_j$ in $W^n_p[0,1]$, then it follows that $(f_j^{(k)})_j$ is Cauchy in $L^p[0,1]$ for all $k = 0, 1, \dots, n$. Hence there are $g_{k} \in L^p[0,1]$ such that $(f_j^{(k)})\to g_k$ for $k = 0, 1, \dots, n$. From this how to prove that $g_k=g_0^{(k)}$ for all $k = 1, \dots, n$? Thanks. EDIT I tried to proceed as follows: $f_j \to g_0$ in $L^p$ $\implies \text{for some subsequence }f_{j_l}\to g_0$ a.e. on $[0,1]$. Then we have $$g_0(x)= \lim f_{j_l}(x)= \lim \int_0^x f_{j_l}^{'}=\int_0^x\lim f_{j_l}^{'}=\int_0^x g_1$$ for a.e $x$ in $[0, 1]$. This implies $g_0'(x) = g_1(x)$ a.e. $x$ . Now similarly we can prove others. Then since $f_j^{(n-1)}$ was absolutely continuous functions with $L^p$ derivatives we can use this to prove that $g_{n-1}(=g_0^{(n-1)})$ is also absolutely continuous with $L^p$ derivative. And this shows that $g_0 \in W^n_p[0,1]$. Is there any mistake?


Hiding part of the text when certain macro is enabled

Problem  I am now preparing exercises for the course I am going to teach next quarter. I have two concerns   Writing problem descriptions and corresponding solutions in two separated files are pretty annoying since it may require lots of copy and paste in later days. Using hyperlinks to jump between problem description and solution is also annoying since some problem descriptions are rather long and involving a lot of fine details, which would make both my life and students' life harder.   I am wondering if there is a mechanism that could hide selected part of the text from global setting. I know I could use comment but    It seems that I need to comment all individual spots. I do not know how to comment all the parts I need to comment (there are more than 200 exercises I am planning to write).


Question: Suppose you wanted to model a Ferris wheel using a sine function that took $60$ seconds to complete one revolution. The Ferris wheel must start $0.5\,\textrm{m}$ above ground. Provide an equation of such a sine function that will ensure that the Ferris wheel's minimum height of the ground is $0.5\,\textrm{m}$. Explain why your equation works.  Format of equation: $y = a\sin k(x - d) + c$ I need help because I don't understand how to determine the equation. For example: how am I suppose to find the amplitude and the $c$ value if I only have the minimum value and not the maximum value? Also, I don't understand how to find the phase shift (value of $d$) if I am only given the minimum value and the period. Please help!


Why would I buy a bond with a negative yield?

The only reason that I can think of is because I expect the bond to appreciate in price thus offsetting the loss in yield. I could still end up with less money than I started with, if I hold the bond until maturity. Ultimately, the only scenario where I would want to buy a bond with a negative yield is because I anticipate deflation and even lower rates in the future. Is this correct, or is there another reason?  Currently, a lot of the global government bond market is trading on negative yield, and there are even some corporate bonds that are too.


Please help identify this children's story about a family robot that runs away to avoid being destroyed

I'm trying to find a children's/YA book.  I remember it being about a family's robot that is about to be either destroyed or have its mind wiped.  The boy that it belonged to orders it to run away to save it.  I think it was thought to be defective for not following some of its prime directives.  The story is set on either the Moon or Mars and the people live in domes.  During the story, the boy meets up with the robot and both helps and is helped.  I don't believe it was I, Robot.  It wasn't a short story or stories, but a children's book.  At a guess, I'd say it was written for 10-14 year-olds. I keep thinking the book was called "Run, Robot, Run" but I can't find it by that title.    I don't know if it had a positronic brain, but it may have been something like that.  I mostly remember that the book started off almost immediately with the child yelling "Run, robot, Run!" and most of the rest of the book being about the robot trying to escape/hide with the boy's help and a growing sense of self.  Thank you!  It is the Runaway Robot, I remember that book cover.  Greatly appreciated!


Eulerian orientations on connected countably infinite graph

Let $G=(V,E)$ be a locally finite graph with $V$ countably infinite. Assume that each vertex has even degree. Does there necessarily exist an Eulerian orientation on $G$? That is, is there a way to direct the edges of $G$ so that the number of edges going into a vertex $v$ is same as the number of edges going out of $v$? I know that the answer is yes in the case of $2$-connected graphs as is mentioned here    However, what if we drop the $2$-connectedness condition? That is, if we drop the property that $G$ is still connected upon the deletion of any one edge can we still find an Eulerian orientation?


Running 64 bit programs on a 32 bit system

As the title says, is there a way of running a x64 bit program on a 32 bit system ? If not, is there an emulator or is there a way of upgrading from 32 bit to 64 bit for free?  NOTE: I am using Windows 10.


this question is by no means a new question, however previous questions have been unable to exactly answer my question. I'm attempting to obtain analytical results and then plot the results of a central field system when given the initial position and velocity of the particle. I know this is just an Initial Value Problem and I have already programmed a Runge-Kutta method, which I would hope to use, or even the scipy.linalg.solve_ivp. However, I don't know how to start properly. For my RK method, I can apply a (2,2) ndarray to my system then iterate, but I don't know what this matrix would take the form of, i.e. what would be the elements general form look like?


Changing major after BS and MS in CS and double major in Physics for PhD in Mathematics

Before telling about my background, I'd like to say that I did look at several similar questions, but neither involved my case (at least, not as far as I could see).   Now the background: I majored in Computer Engineering. I have expected more of Computer Science, but it was mostly business-oriented coding education (maybe I am being a little too harsh on this). So in my second year, I applied for a double major in Physics, thinking it might be more satisfying. In fact, I did enjoy Physics more than CS (or, CE in my case), and found it much more challenging and meaningful.  However, I ended up finishing my main major (CE), before Physics, so I applied for MS in CE in the same university, feeling the workload might be too little otherwise. I got accepted, and am currently enrolled in this program while taking 2-3 courses left from undergraduate Physics program. (My subject in MS is Computer Vision.)  But one thing I noticed over these years is that, for Physics I do not feel like I have the right mindset (seems that I lack a practical approach to things), and CE feels a little meaningless. Considering that I focused on Mathematical Physics, and more of the mathematical stuff in CS, I thought maybe Mathematics is the right place for me. But I cannot yet tell if I genuinely want Maths, or just whining about what I have at my hands.   So I have two questions, actually:   What are my chances if I apply for PhD in Number Theory? Do you recommend changing the field? Can you share other people's experiences in similar cases?   For the application part, I must add that I do not have an outstanding transcript in neither of my majors (around 3.4 GPA in both fields -Physics might be around 3.5 too), although I did get a paper published which was about relativistic quantum mechanics.   Edit: This question is different from what is suggested as duplicate as this particularly involves the case of a double major background. Specifically, whether the case of double major suggests the admission committee a versatility in working different fields or not. So I do not think this should be regarded as a duplicate question.  Edit2: Experience in proofs I have taken Discrete Mathematics and Formal Languages and Abstract Machines, in which we mostly used induction to prove things. Apart from that, in the mathematical methods courses we have gone through the proofs of Stokes' theorem, divergence theorem, etc. Although I mostly can understand a proof reading through it, and working out some things that seem off, I would not say that I am good at mathematical proofs, nor that I am much experienced with them.


Equation of conic: Given five points on it

How do we find the equation of a conic given five points on it?   Is there a quick method, such as some determinant; which may help solve for the equation easily?  Of course, one may just substitute the given 5 points in the general equation of the conic, and solve for the unknowns - but that method is very time consuming and exhausting.   Could someone please help me generate a matrix, whose determinant gives the required equation of the conic?  Data available: Coordinates of 5 points on the conic.   Thanks in advance!   P.S. I've successfully generated a determinant for the equation of a circle, given three points on it.   Here's the link to where I first found it, and later proved it -


Is it impossible to add certain NBT tags to commands in PE?

I've read a post that said that you can only add the CanDestroy and CanPlaceOn tag, is that actually true or is there a way to do other things, like getting unbreakable items? Edit: This is not a duplicate. I've read the post and I just want to know what exactly it meant.


I'm one of those guys. I want to play with some foreign players (GURPS, WOD) via the web. Sorry for a bit opinions based question, but I need it in this way.   What are the potential problems?  Where are the best chances for finding these games?  More particularly, where non-native speakers not something too unaccustomed and where the game can't be easily ruined by a bad Skype-link(etc.) plus far from native listen comprehensive?


warning returns while using sudo apt-get update, how to fix

W: http://mirror.jmu.edu/pub/mariadb/repo/5.5/ubuntu/dists/trusty/InRelease: Signature by key 199369E5404BD5FC7D2FE43BCBCB082A1BB943DB uses weak digest algorithm (SHA1)


A closed ball in a metric space is a closed set

Prove that a closed ball in a metric space is a closed set   My attempt: Suppose $D(x_0, r)$ is a closed ball. We show that $X \setminus D $ is open. In other words, we need to find an open ball contained in $X \setminus D$.   Pick $$t \in X-D \implies d(t,x_0) > r \implies d(t,x_0) - r > 0 $$ Let $B(y, r_1)$ be an open ball, and pick $z \in B(y,r_1)$. Then, we must have $d(y,z) < r_1 $. We need to choose $r_1$ so that $d(z,x_0) > r$. Notice by the triangle inequality  $$ d(x_0,t) \leq d(x_0,z) + d(z,t) \implies d(z,x_0) \geq d(x_0,t) - d(z,t) > d(x_0,t) - r_1.$$  Notice, if we pick $r_1 = d(t,x_0)-r$ then we are done.  Is this correct?


Questions concerning GARCH modelling in R (mean equation, forecast evaluation)

I apologise, if these question are trivial, but I am currently trying to estimate a family of GARCH models for a selection of return series as part of an undergraduate project for which I am having to do a fair amount of self-teaching.  I am following the instruction given in Tsay: Analysis of Financial Time series and upon finding the expected ARCH effects using LM/LB tests, would now like to proceed estimating the models.   However, I am having difficulties selecting the order of the mean equation, which I assume to be some form of ARMA model. Given that the mean equation and GARCH model should be jointly estimated, how do I go ahead selecting the order of the mean equation?  Tsay suggests the typical Box-Jenkins methodology of either using AIC/BIC/AICc or PACF plots when building an ARMA model, however, I believe this would lead to a sequential estimation process, based upon wrong assumptions, as volatility is not constant over time.  Do I estimate (for instance) 25 different ARMA(p,q)-GARCH(1,1) models and compare their AIC/AICc/BIC or how would I go ahead selecting the mean equation?  Furthermore, is there a package in R that gives me a series of one-day ahead forecasts of volatility based upon previously estimated parameters?  So, given an GARCH-model that has been estimated in-sample, can I use the in-sample coefficients to predict one-day ahead forecasts out-of-sample?  I luckily have a series of Realised Variance to work with when comparing the models.


jQuery: how can I pass this to my function on click button?

Below code works properly until I insert new row by jQuery. 'delete' button doesn't work in my new row.   $(".delete").on("click", function() {   $(this).closest('tr').remove(); }); <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous"> <link rel="stylesheet" type="text/css" href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">

        <input type="text" />


How does one prove that proof by contradiction has completely and utterly failed?

to clarify the difference between this question and the supposed duplicate, absolutely nowhere do I mention the proof being attempted in the other question. It merely serves as an example related to this question.  Now, the way I view proof by contradiction is like this:  We have two logical statements $a$ and $b$ and we claim that "if $a$ then $b$".  We assume $b$ is false (given $a$) and we attempt to find some kind of contradiction with something we assume is true at the beginning (generally it tends to be proving $a$ is false).  Now, proof by contradiction can "fail" by resulting in no contradiction (i.e. that $a$ ends up being true when $b$ is false). However, this seems like a proof that the original statement is false. What I'm asking is more like how one detects or proves that when $b$ is false the truthfulness of $a$ is unprovable. Basically, that $a$ and $b$ are incapable of proving each other.  A good example of this is the parallel postulate of geometry. From what I heard (paraphrasing) "a failed proof by contradiction showed that there existed consistent systems where it was false and that it was unprovable from the other postulates". I'm not quite sure how that worked. Could someone please explain (in general) how one proves a proof by contradiction fails this brutally? I'm not asking specifically how it was done for the parallel postulate, but just how one goes about doing it in general?


Insert DIV container below 1st search result

How can I insert a DIV just below the first search result (between result #1 and #2)?


I'm having trouble with the grub rescue. I am following the tutorial , but I have the following problem.  I have to run the command  set prefix=(X,Y)/path   making (X,Y)/path the path where the .mod files are located. I found that directory to be (hd0,gpt7)/usr/lib/grub/x86_64-efi. When I set that prefix and try to run the insmod commands, I get:  error: file '/usr/lib/grub/x86_64-efi/i386-pc/linux.mod' not found   What I think the problem is here, I have located the linux.mod file in the directory /x86_64-efi, but then GRUB tries to find it at /x86_64-efi/i386-pc, adding that directory that doesn't even exist there (I checked its existence with ls).  I made another test after this. I did:  set prefix=(hd0,gpt7)/usr/lib/grub   But I got the same error:  error: file '/usr/lib/grub/i386-pc/linux.mod' not found   It seems as it always adds the path i386-pc.  How can I force GRUB to look for the files in the directory I want? Or is my problem something else?


Can there ever be any problem when using gedit to edit system files with 'sudo -H gedit'?

I am relatively new to Ubuntu, I noticed that in answers on this site, when people suggest editing system files, the command they give is always sudo nano or sudo vi. Because I dislike using terminal based text editors, I usually use   sudo -H gedit   instead, and so far it worked perfectly fine.  Can there ever be any problem with using gedit to edit system files or is choice of text editor is purely up to the person's preference? Is there anything that I should keep in mind (like encoding) when editing these files?


Splitting all lines in layer at vertices using QGIS

I want to automatically split all lines in a QGIS layer at their vertices (). I've done a Google search and found , which is quite close but the workflow is complicated. Because I'll have to train my co-workers (who are unfamiliar with GIS) to use this tool, I want something as simple as a plugin or something that doesn't require GRASS. Since it's been a long time from 2010 - the time of , I wonder if there is any better way to achieve the same result?


I’m having trouble finding the answer to my exact question after extensive searching on here and other places. I am currently a Level 3 Wizard / Level 1 Fighter. I aim to focus on my wizard levels but I was thinking about taking Level 3 Fighter to gain access to the Eldritch Knight martial archetype. Basically what I want to know is will being an Eldritch Knight give me access to more spell slots outside of wizard spell slots alone? Also, will it enable me to learn more spells that I could not as a wizard only character. I hope this makes sense and thank you in advance for help. What I’m hoping to hear is something like wizard gives me 4 spell slots for level 1 and being Eldritch Knight gives me another 1/2 level 1 spell slots etc etc.


WPF: Slider with an event that triggers after a user drags

I am currently making an MP3 player in WPF, and I want to make a slider that will allow the user to seek to a particular position in an MP3 by sliding the slider to the left or right.  I have tried using the ValueChanged event but that triggers every time it's value is changed, so if you drag it across, the event will fire multiple times, I want the event to only fire when the user has finished dragging the slider and Then get the new value.  How can I achieve this?    [Update]  I have found  on MSDN which basically discusses the same thing, and they came up with two "solutions"; either subclassing the Slider or invoking a DispatcherTimer in the ValueChanged event that invokes the action after a timespan.  Can you come up with anything better then the two mentioned above?


Why do we say 'last Monday morning' but not 'last morning'?

There was a very similar question asked about 'last night' and 'yesterday night'  but I didn't really think the question was answered that definitively. Also, I thought about how we use other expressions that include last + date/time a bit more.  Is this because last Monday morning is unambiguous, and yesterday morning is also unambiguous whereas last morning is? Why doesn't last morning just mean the morning that passed if it is night time (and you are referring to a time in the same day), and if it is morning then it refers to yesterday's morning? I think this is still a probably with last Monday morning if you are using this expression on a Monday just after morning.


Late-2011 MacBook Pro’s and Snow Leopard

Has any member here performed a software downgrade from the pre-installed Lion 10.7.2 to Snow leopard 10.6.8 on any late-2011 MacBook Pro (any size) and if it was successful or failed and what you found? Thank you.


Demonstration of $\int_{-a}^a \frac{f(x)}{1+e^x} \,dx= \int_0^a f(x) \,dx$

Good morning,  Can you give me a help to demonstrate this proposition:  $f$ is an even and continuous function on the interval $[-a,a], a>0$. Demonstrate:  $$\int_{-a}^a \frac{f(x)}{1+e^x} \,dx= \int_0^a f(x) \,dx$$


Can I shift bits into an integer that is initially 0 using a for loop that iterates 8 times to get some 8-bit number in Java?

I am working on implementing an 8-bit adder abstracted with code in Java. This 8-bit adder is built from 8 full adder circuits. For those who don't know what a full adder is, it's a circuit that computes the sum of 2 bits.   My intention was8-bit  to use a for loop to add each corresponding bit of the adders 2, 8-bit inputs such that a new bit of the 8-bit result is computed each time the for loop iterates.  Would it be possible to store the new computed bit of each iteration in a variable holding the 8-bit result using bit shifting?  Here's an example to help explain what I am asking. The bold bit would be the one that is shifted into the int holding the result.     0b00001010   +     0b00001011   First Iteration (addition starting w/ LSB)     Sum: 1      Result: 0b00000001      Carry: 0   Second Iteration     Sum: 0      Result: 0b00000001      Carry: 1   Third Iteration     Sum: 1      Result: 0b00000101      Carry: 0   Fourth Iteration     Sum: 0      Result: 0b00000101      Carry: 1   Fifth Iteration     Sum: 1      Result: 0b00010101      Carry: 0   Sixth, Seventh, Eigth Iteration     Sum: 0, 0, 0 respectively      Result: 0b00010101      Carry: 0, 0, 0 respectively


Prevent browser caching of AJAX call result

It looks like if I load dynamic content using $.get(), the result is cached in browser.  Adding some random string in QueryString seems to solve this issue (I use new Date().toString()), but this feels like a hack.   Is there any other way to achieve this? Or, if unique string is the only way to achieve this, any suggestions other than new Date()?


Anamorphic Perspective in Illustrator or Photoshop?

I'm trying to find a way to distort artwork to emulate those crazy chalk art pieces you see all the time, like this:    I know how it's done:    ...but I'm wondering if there is an Illustrator or Photoshop plugin available to apply the distortion for me.  Currently, I do the distortions manually with Mesh Envelope, but it's tedious. There has to be an easier way. Any ideas?     EDIT: Here is one of the recent real life projects I did that used this sort of technique, but calculated manually, stair by stair:       Here is the desired view point:             And here is an off angle view point:


I've recently started a major redesign for a large web-based financial tool. To aid future development, I'm planning on generating a UX style guide that outlines best practices for things like forms, page layouts, animations, etc...   The existing application is a big jumble of forms with little grouping or organization. I can see a few major categories, (Object CRUD forms, static data, user session management controls, etc...) but there's a lot of very custom functionality that doesn't fit the mold.  The company I'm working with does it's development overseas, and this documentation is intended to support future development. I'm not looking to design the most amazing UX ever, I just want things to be functional. What's the best way to communicate designs to remote teams?  Here's my question:  What's the best way to approach a big messy project like this? (Major groups first, then focus on each custom function? Do you even include the custom functions in the documentation?)


How to manually write an element of group ring in GAP.

Suppose, we consider  R:=GL(29); (Galois field of order $29$) G:=SmallGroup(7,1); (cyclic group of order $7$) H:=Group Ring(R, G); (this generates the group ring).  Suppose that GAP is unable to fetch the list of elements. Then how can I do the following: (i) check whether an element is in H or not and how to write that element. (ii) how to select some element of H, let's say $n$th element.


Device or material that is (near) 100% transparent from one side and (near) 100% reflective from the other side?

Looking out of the window at night from a lit room, you see yourself reflected in the window and, depending on the lightness or darkness outside, you also see things outside. We can say:     Some light from the inside is reflected and some light from the outside comes in.   Is it physically (and technically) possible to have a "window" screen for which the the two 'some' in the sentence above can be changed to 'all', as in the diagram?     Light from the left passes through 100%, independent of angle. Light from the right is reflected 100%, independent of angle.   I wonder if this is possible and if yes, if there exist technical solutions, or whether some physical principle prevents this?


Both     Bob: Who are you?      Joe: I'm Joe.   Or     Bob: Who are you?      Joe: I am Joe.   Is fine.     Bob: Are you Joe?      Joe: Maybe I am.   Seems fine, but     Bob: Are you Joe?      Joe: Maybe I'm.   Seems a bit weird. Is it correct to say it like that?


There is a Windows 10 lock screen wallpaper that really caught my attention. Does anyone know the location of this picture?

The information given by Windows 10 is that this picture was taken somewhere in Montenegro. Can someone please give the exact location?


Can I install Lineage OS on unsupported device?

I don't know what to do, because I have older phone HTC Desire 526G and updates are just not pushed and I believe that they will not push them ever, but out there there is so many vulnerabilities for the OS which I'm running currently 4.4.2 Kitkat.  Buying a new phone is not an option for me right now. So my question here is; can I somehow install Lineage OS on that device? What is the worst it can happen?


Counteracting a metallic taste in canned tomatoes?

I used some canned tomatoes to make chili, which normally works fine, but today it has a really strong metallic flavor. From what I can tell, this is just because they're probably low-quality, so I won't be using this brand again.  Anyway, is there anything I can do to save this chili? I didn't notice the flavor until I added everything else.


Lightcycles or whatever it was called like.    Given a 2d array representing the game map, where each element can be either 0 or 1 (0 representing blank space and 1 representing filled space), what is the algorithm used for TRON enemy A.I?


Construction of Continuous Functions, help me

Show, if $f:X->\mathbb R$ is continuous at point $a \in X$, then it is bounded in a neighborhood of the point $a$. That is, it exists $\delta>0$ such that $U_{\delta}=X \cap (a-\delta,a+\delta)$ or $f(U_{\delta})$ is bounded. Help me, please


Where can I find help files or documentation for commands like \@startsection for LaTeX?

I can't find official documentation for the \@startsection command. I already looked in:   LaTeX Wikibook LaTeX: Structured document for TEX, 2008 beginLatex — a book that comes with ProTeX in the files that comes with MikTeX in the folder doc   and Google. I found a lot of sites that show examples and discussions about it but I'd like to find the official help or document.


Is there a general formula to the: sum n!

For example as the: sum n   has the general formula >>> n(n+1)/2  Is there a formula for the n!


How do I create a YAML file in order to set a static IP for my /etc/netplan directory? Server 18.04 LTS

I currently do not have any YAML files in my /etc/netplan directory than I can edit in order to set a static IP for my Ubuntu 18 server. I have tried:  sudo netplan generate   It returns no errors but there is also no new files (or any files for that matter) created under /etc/netplan. Can I use nano to create a file a save it with a .yaml extension and still use  sudo netplan apply   in order to update my Ethernet interface settings?


does it matter if its internal or external usb hdd?

Can i install ubuntu(any flavor at that) onto am external hdd and will it run normally? If so what are the procedures and how do i do it? I wanted to install into a usb external hdd


This is a question which I seem to have tackled multiple times, solved each time after reading a dodgy internet explanation, then partially forgotten about and retackled half a year later. It is time to put an end to this.  So first, at the power plant, a set power is produced. Let's call this $P_g$. Then there is a transformer that can say hypothetically transform this power into any voltage, and therefore following the equation $V = IR$, any current desired. Cool so far.    Consider the case where you simply condense all the power lines into a single resistance, R. Now we can relate the power lost from the resistance $P_l$ as $P_l = I^2R$. By inspection, as the resistance is a constant, lowering the current drastically lowers the power lost. This is great, as lowering the current means raising the voltage, which seems all handy dandy.  But wait: here's my problem. Can't the Equation for power loss be translated as thus:  $P_l = I^2R$  $P_l = IV$  $P_l = \dfrac{V^2}{R}$  BAM. Now the power seems to depend upon the voltage alone, as the resistance does not change, so it seems pretty logical that REDUCING the voltage reduces the power lost. Nuts. Evidently I have done something wrong. Lets take a simple case, $P_g = 10$. Lets say I set the voltage to 10, and the current to 1, and the resistance to 1 as well. That seems ok, as $P = VI$. Now lets use the two equations we have to determine the loss of power.  $P_l = I^2R = 1$  Seems logical, the current is 1 definitely, and the resistance is 1 definitely, so the power loss is one. Makes sense too.  $P_l = \dfrac{V^2}{R} = 100$  WHAT IS LIFE!! But this seems pretty logical to me too, the voltage across the resistance is 10 (is it not? I might be forgetting something fundamental here? not sure), and the resistance is 1.   Any help is helpful, I'm probably just being silly at one step or another.  EDIT  Well I was right, I WAS being silly i think. I pretty much completely ignored the fact that $V = IR$, so in the case where $P_g$ is 10, and the resistance was 1. I seem to have run into a complication now. If I set the voltage to 10, according to $P = VI$ the current should be one, but according to $V = IR$ the current should be 10. I run into a conundrum? I am now thoroughly confused. Any help is helpful.


Question. Suppose that all the tangent lines of a regular plane curve pass through some fixed point. Prove that the curve is part of a straight line. Prove the same result if all the normal lines are parallel. I am working on differential geometry from the book by Pressley and I have a doubt in the solution of the above question whose (brief) solution is given by: Solution: We can assume that the curve $\gamma$ is unit-speed and that the tangent lines all pass through the origin (by applying a translation to $\gamma$). Then, there is a scalar $\lambda(t)$ such that $\gamma'(t) = \lambda(t)\gamma(t)$ for all $t$. Then, $\gamma '' = \lambda'\gamma   + \lambda \gamma' = (\lambda' + \lambda^2)\gamma$. Can anyone please explain me how does this line follow : " Then, there is a scalar $\lambda(t)$ such that $\gamma'(t) = \lambda(t)\gamma(t)$ for all $t$." Thanks in advance.


I have    public Object get(int index)     {         if (index <= 0)             return null;          Node Current = head.getNext();         for (int i = 1; i < index; i++) {             if (Current.getNext() == null)                 return null;              Current = Current.getNext();         }         return Current.getData();     }   this method for a linked list to get something in an index. That something is a Painting object, and I want to get the title of the painting using a getTitle method within the Painting class.  Here is what I tried to do,  for(int i = 0; i < paintings.size(); i++){         Painting x = (Painting) paintings.get(i);         System.out.println((i+1) + ": " + x.getTitle()); }   Unfortunately at x.getTitle() java gets extremely salty and gives a null pointer exception. I've tried multiple ways of doing this with different casts and I'm just personally lost. Any help would be deeply appreciated.


Expressing points in fractional dimensions?

Note: I'm not too experienced with branches of mathematics like topology, so a lot of the terminology I use is used pretty loosely.   I think we all understand the fact that a point in $n$-dimensional space is described with $n$ parameters. In 2d space, you have $(p_1, p_2)$ (where $p_k \in \mathbb{R}$), in 3d space you have $(p_1, p_2, p_3)$, so in an $n$-dimensional space you have $(p_1, p_2, ..., p_n)$. I know the way I'm stating this with the notation I use isn't as robust as it could be, but you get the idea.  Going into the world of fractal geometry, we find non-integer dimensional spaces. Applying what I said previously, how would you even express a point in such a space? What does it even mean to be that kind of space? Are you unable to express a "point" in such a space?


"I had fallen asleep" vs "I fell asleep"

Which sentence below is grammatically correct?  I didn't answer your questions because I had fallen asleep early last night.  I didn't answer your questions because I fell asleep early last night.   I'm leaning more toward the second sentence since the time was specified, and I don't see why the past perfect is needed. Please, correct me if I'm wrong, and thanks in advance.


High Voltage Powerlines - clarification of energy loss

I've been having a bit of trouble understanding the High-Voltage powerlines. If I was sending power from $A \rightarrow B$, we have:  Ohm's law $V = IR$  Power lost in the form of heat $P = I^2 R$  Power delivered to $B$ is $P = VI$  But using Ohm's law on the power lost formula, we get $P = V I$ also.  Does this mean that the total amount of power $A$ loses is $P_A = 2 VI$, and the total amount of power delivered to $B$ is just $P_B = VI$? Will transferring energy always result in half of it being lost?


Print only prints after functions are finished executing

I have this code:  def get_endpoint(type):     return "%s/%s.json" % (v2_endpoint,type)  def get_entities(type,endpoint=None,entities=None):     if not endpoint:         endpoint=get_endpoint(type)         entities=[]     r=requests.get(endpoint,headers=header)     entities.extend(r.json()[type])     if not 'next' in r.links:         return entities     else:         return get_entities(type,r.links['next']['url'],entities)  print "Fetching info from New Relic....", servers = get_entities('servers') applications = get_entities('applications') print "Done."   I noticed that it doesn't print the first and last print statements until it has processed those functions. Expected behaviour, I presume.  So, how do I make it print the first line before it starts processing the function?


What's the evidence supporting 1 singular Big Bang?

Possible Duplicate:          I love to dabble with science, I'm by no means a scolar in this field. One thing that haven't seen proven yet (maybe I missed it) is that there was only 1 singular Big Bang where it all started.   As I understand, when Hubble discovered that the universe was expanding, the conclusion was also that it was much smaller in the past. That I follow, but the theories seem to automatically agree on there being 1 Big Bang where everything started.   Couldn't there have been multiple points where matter etc 'flipped' into existence roughly around the same place and time? Is there any evidence for that? Does all the red shift for instance point to 1 spot?   Thanks for your time and knowledge in advance,  Gert-Jan


Find a vector equation and parametric equations for the line segment that joins $P$ to $Q$. Here $P(1,-1,7)$ and $Q(7,5,1)$.   I have tried to find $r(t)$ by using the formula $r(t)=p+t(p-q)$ but it is wrong. I am making a stupid mistake.


Divisibility of $2^n - 1$ by $2^{m+n} - 3^m$.

For what values of $m,n$ natural, do $2^n - 1$ is divisible by $2^{m+n} - 3^m$?  Thank you very much.


From the book First course on DE, there's the problem $2y''+ty'-2y=10, y(0)=0, y'(0)=0$. Implying laplace transform to both sides give a linear homogenuous DE $Y'(s)-(2s-\frac{3}{s})Y(s)=-\frac{10}{s^2}$ and it gives $Y=\frac{5}{s^3}+C\frac{e^{s^2}}{s^3}$, but I'm stuck here. The answer is $\frac{5}{2}t^2$, which means that $c=0$. Now I can't find the reason why $c=0$. Can anyone help???