Disable commandButton after first click to prevent double submission

I have an apex:commandButton on a visualforce page that invokes a method on the controller. There is currently no rerender value set for the button. Instead the controller method returns a PageReference to redirect the user as required.  E.g.  Visualforce:  <apex:commandButton value="Save" action="{!save}"/>   Controller:  public PageReference save() {     // save body ...      // return the user the a parent opportunity     return new PageReference('/' + opp.Id); }   Users are currently able to click on the resulting save button multiple times before the controller completes and returns the PageReference to redirect the browser to an opportunity.  How can I disable the commandButton after the first click?    I tried wrapping the commandButton in an actionStatus and facet, but the need to define the rerender property prevented the resulting PageReference redirect.  E.g.  This will render nicely in the browser and prevent multiple clicks, but doesn't redirect to the Opportunity on completion.  <apex:actionStatus id="saveStatus">     <apex:facet name="stop">         <apex:commandButton value="Save" action="{!save}" status="saveStatus" rerender="saveParentBlock" />     </apex:facet>     <apex:facet name="start">         <apex:commandButton value="Saving..." disabled="true" status="saveStatus"/>     </apex:facet> </apex:actionStatus>     There is a similar question . I need to support an existing PageReference redirect, which slightly alters the requirements.  Force.com Discussion Boards:   Ideas:


Is there a way to scale icons in the launcher smaller than 32 pixels?

I am using 11.10 beta and want to give Unity another chance (I was always very fond of XFCE) ... anyway is there a way to scale the Icons to a really small size, let's say ~25?? And can this also be done for unity-2d, I figure the Compiz configuration tool won't work with Unity-2D?


What does the graphics card do with the fourth element of a vector as the final position?

From  it appears you would want a four-element position vector, as it is simpler to modify its position with matrix multiplication.  On its own this would imply the fourth element should simply be ignored when considering it as a representation of a 3D point (assuming no transformation), but I know this is not true, as when I supply a vector4 to the GPU, if the fourth element is not one, it is not rendered - why?  What is the significance of the fourth element, once it is in the rasterizer?   EDIT: On review this question was somewhat poorly worded; it would be more accurate for the second paragraph to say: "if the value of the fourth element is not within a certain range, it is not rendered 'correctly'/'as expected'".


MWE  \documentclass[a4paper,11pt]{article} \usepackage{enumitem} \begin{document} \setenumerate[1]{label=\textbf{\arabic*)}} \begin{enumerate} \item Problem One\label{one}.  \end{enumerate} See \ref{one}. Problem. \end{document}   Output    But that I want    That is the right parenthesis removed. I'm waiting for your help.


Is there an option to create and Opt-in a user in the same API call?  At the moment I can find it only in 2 separate calls. Create then Opt-in to a keyword.  It will save us a lot of resources.


I have bumped into one simple task which I am not able to prove:  How to prove, that number $ \frac{1000!}{(100!)^{10}} $ is integer?


List of programming related StackExchange websites

I want to start a list of the programming-related StackExchange websites, since there are more and more SE sites that might have a more focused community, rather than SO.  If you have more than 100 rep feel free to edit the first answer itself. Otherwise post a link seperately and someone will add it in :). I'm not doing this for rep so please don't close this question.  Lists


How to correctly calculate the colour of the sky?

It is well-known that the sky is blue due to .    What bothers me though is the question how to actually calculate the spectrum of the scattered sunlight. Yes, use one of the formulas involving  $$I\propto \frac{1-\cos^2\theta}{\lambda^4},$$  that is clear, and the solar black-body spectrum has to be convoluted with the three human eye sensitivity curves to obtain an RGB image. But since our visual perception system (a.k.a. eyes) evolved such that the VIS-range is not strongly absorbed, I assume multiple scattering needs to be considered. So the formula above has to be applied to all paths involving no, single, double, triple etc. scattering, in other words there'll be a path integral involved.  Is there a closed form solution for this multiple scattering? Or at least an established routine to do the calculation?


Tom Riddle used Ginny Weasley to open the Chamber of Secrets, which requires the ability to speak Parseltongue.   Ginny must have spoken Parseltongue to open the chamber -- does this qualify Ginny as a Parselmouth?


How to round a mathematical answer to 5 decimal places

I have written a java program that does exactly what it's supposed to, however, the answer needs to be rounded to 5 decimal places.   I've googled it a ton, but every post I see has a double input. This is a sumArea answer that needs to be rounded.  public class COSC_HW13 {     // Main method     public static void main(String[] args)      {     // Create an array of four objects     GeometricObject[] array = {new Circle(5), new Circle(8),     new Rectangle(3, 4), new Rectangle(4, 2)};      // Display results     System.out.println("Total area of elements in array: "              + sumArea(array));     }      // Returns the sum of the areas of      //all the geometric objects in an array     public static double sumArea(GeometricObject[] a)      {         double sum = 0;         for (int i = 0; i < a.length; i++)          {             sum += a[i].getArea();          }         return sum;     }  }


Is the sentence, "I wrote him," grammatically correct?

I am wondering if the sentence I wrote him. is grammatically correct. Can I wrote him. take the place of I wrote him a letter. and/or I wrote to him.? Can one omit the preposition to? Can one omit the (what I think is) the direct object a letter?


How to find a player's redstone clock (or other aggressive circuitry)?

I'm an admin for a minecraft server where I suspect one of the players has set up a fast cycle redstone circuit. The reason is the server uses what seems to me to be too high of cpu for only one or two players logged in, and lately there always seems to be a bit of lag.   I've found where he had built one before and he said that he wouldn't build one again, but knowing him, it's likely that he build one similar and not "exactly" like before.   So, are there any good ways to find where there is a redstone circuit like that, or better, is there a bukkit plugin that I can use to globally disable such circuits?  edit  Just to be clear, I'm not an op, I'm the full blown server admin (I pay for the VPS) lol. It's a windows server 2008 rc2 server so I have access to all files. It's currently running bukkit so that's why I would like to know about bukkit plugins that would make my life easier.   I did search for bukkit plugins but I couldn't find any "official" ones, which is why I asked for other unreleased or beta plugins. =)


What can I do with "stale" checks? Can I deposit/cash them?

Back in December 2013, I paid the insurance for a "friend's" business on my credit card so that it wouldn't get canceled.  The amount was $1,700+ but before I did, I requested a post-dated check for repayment.  I received 3 separate checks for $575 each dated 2/1/13, 3/1/13 and 4/1/13.  The first problem is that they were all immediately stale checks because the year should have been 2014 but I'm sure it was an honest mistake.  Anyway, when those dates had passed, I inquired about cashing them as I didn't want them to bounce and incur more expenses for bounced checks (unfortunately, they are drawn on a bank that does not have any offices near me).  I kept getting promises of dates that I would be able to cash ONE OF THEM but that still hasn't panned out.  I'm thinking now I should just deposit all 3 and let them bounce if they're going to just so I have something to start legal action with.  However, I'm not sure what to do about the stale date.  Can you offer any advice for this Central NY loan-not-getting-repaid fool?


I recently heard someone say 'between he and I there's difference' Is it correct not to use him and me?


Smallest multiple whose digits are only ones and zeros

I have a collection of typewritten pages that formed the basis of a third year problem solving course offered about 25 years ago at U. Waterloo. I've been slowly working through the problems and have come up with a solution to one of the questions but was wondering if anyone had a better solution.  The question is: Find the smallest natural number composed only of ones and zeros which is divisible by 225.  My solution: We are looking for a positive integer $k$ so that $N=225k$ has only ones and zeroes in the digits.  Since any multiple of 5 has a 0 or 5 for the last digit, then k must be even.  But $2\times 225=450$, so it really means that $k$ must be a multiple of 4.  Now $N=900K$, where $4K=k$.  Let $100K=\sum_{i=0}^\infty a_i 10^i$, where (potentially) an infinite number of the $a_i$'s vanish.  The solution method is to look at each term $a_i$ starting with $a_0$ and choose the $a_i$ so that the ones digit of the product $9a_i + c_{i-1}$ is a one or zero, where $c_{i-1}$ is the carry from the previous product.  This forms a tree, starting with $a_0$ at the root.  The smallest $N$ is found from the smallest limb of the tree.  Each of the following congruences are $\mod 10$.  We choose $a_0$ so that $9a_0 \equiv 0$ or $9a_0 \equiv 1$.  Only $a_0=9$ works here, so there is a carry of 8 when considering $a_1$.  Then we have the congruences $9a_1+8\equiv 0$ or $9a_1+8\equiv 1$.    This gives two options to consider for $a_1$: either $a_1=8$ with a carry of 8 or $a_1=7$ with a carry of 7.  The first just leads to a larger number for $N$, so we ignore it and move on to $a_2$.  This has four options, but the only one we can use that has smallest $N$ is $a_2=6$ with a carry of 6.    Continuing in this way leads to $K=12345679$ and $k=4\times 12345679 = 49072716$, which means that $N=11111111100$.  This was verified by a simple computer program I wrote that checked all of the smaller multiples.  Question for the group:  For different numbers from 225, this leads to very dense and deep trees when solving for $a_i$.  In fact, I had a originally solved this question using 255 instead of 225 because I misread it, which had a much denser tree because none of the branches could be eliminated at each step.  Does anyone know of a cleaner/simpler solution?


Why does Newt say Lumos Maxima in the Fantastic Beasts trailer?

At the beginning of , someone (who I think is Newt Scamander) says the spell "Lumos Maxima". The problem is that Lumos Maxima is not a canon spell. The spell that everyone uses in the books is Lumos. (Rowling has said "That's showbiz!" when asked about the movies versions of the spells.)  A fact that further complicated matters is that JKR said  that she "wrote the entire script".  So why does Fantastic Beasts have Lumos Maxima?  (An out of universe answer is fine, I'm more of trying to figure out where this movie stands canonwise than trying to mesh two incompatible things.)


Simple case, for comments:   Navigate to a question page that has a link away from the current SE site. Upvote a comment. [Most probably there’s an issue with flagging as well.] The comment score is updated. Click the link. [Most probably the link is not essential and any navigation works.] Click the browser back button to return. Observe your upvote is not displayed, try to upvote once more. Get an error popup saying “you cannot mark a comment more than once”, observe that your upvote is still not displayed. Refresh page, observe your original upvote is correctly recorded.   Complex case, for questions and answers (could actually be a feature, or rather a somewhat confusing workaround that wasn’t applied to comments by mistake):   Do steps 1–5 above, but for a question or answer rather than a comment. Observe what looks like a successful upvote. Refresh page, observe that the question score has (correctly) only been increased once even though you pressed clicked the upvote arrow two times overall.   ETA I’d argue that, even if showing the page as it was when I navigated from it is infeasible, at least the reaction to upvoting an already-upvoted comment should be the same as for upvoting an already-upvoted question or answer: either both should show an error message, or both should succeed.  [Browser: Chromium 64.0.3282.167 on Linux x86-64]


why a two-step process to live boot with UEFI?

Assuming that the  works to allow the  thumb drive to boot from an  laptop which boots with UEFI and GPT:  Open the notebook and press quickly F2 to enter the BIOS. Under the MAIN menu, enable the F12 Boot Menu option. Under the BOOT menu, select Legacy boot and press F10 Save & Exit. While the notebook is rebooting, press F2 again to enter the BIOS. Under the BOOT menu, select as your first boot option the USB HDD stick (your USB stick). Press F10 Save & Exit.   why the two step process?


I've been trying to find the source of why my render distance is so low (I'm new at using LWJGL and don't know the complete basics yet) and I believe it falls down into this code. My idea for my game (Well, this is more of a practice run to get used to coding 3D games.) is going to be a small island with a size of around 800 which seems extremely low however it is only loading a small portion which I'd estimate to be 600. The code for my MasterRenderer class is below. createProjectionMatrix() is called in the constructor and prepare() is called at the beginning of every render.  private static final float FOV = 70; private static final float NEAR_PLANE = 0.01f; private static final float FAR_PLANE = 1000f;  public void prepare() {     GL11.glEnable(GL11.GL_DEPTH_TEST);     GL11.glClear(GL11.GL_COLOR_BUFFER_BIT | GL11.GL_DEPTH_BUFFER_BIT);     GL11.glClearColor(0.49f, 89f, 0.98f, 1); }  private void createProjectionMatrix() {     float aspectRatio = (float) Display.getWidth() / (float) Display.getHeight();     float y_scale = (float) ((1f / Math.tan(Math.toRadians(FOV / 2f))) * aspectRatio);     float x_scale = y_scale / aspectRatio;     float frustum_length = (FAR_PLANE - NEAR_PLANE);      projectionMatrix = new Matrix4f();     projectionMatrix.m00 = x_scale;     projectionMatrix.m11 = y_scale;     projectionMatrix.m22 = -((FAR_PLANE + NEAR_PLANE) / frustum_length);     projectionMatrix.m23 = -1;     projectionMatrix.m32 = -((2 * NEAR_PLANE * FAR_PLANE) / frustum_length);     projectionMatrix.m33 = 0; }   I've tried altering the FAR_PLANE and NEAR_PLANE with no results other than some minor bugs with changing the NEAR_PLANE to a small number.


How to prevent iPhone from vibrating during calls?

I can't figure out how to prevent my iPhone SE (iOS 10.2) from vibrating when messages arrive while I'm on a call (that is, it vibrates right into my ear). This happens regularly, and I'm sure it occurs with other models/software versions.  I cannot find any setting regulating this, therefore it looks like a major bug: it doesn't have any function and interferes with the normal phone usage.  Does anybody know if anything has been/is being done with respect to this issue?


I have been stumped in characterizing Medbh McGuckian's style of poetry: she often vividly describes the actions of things in her works to imply what they are. For example, within the context of war, the following stanza could be read such that "From behind the moon boys' graves \ bleed endlessly" refers to the mothers or lovers of dead men sent off to war. Thus making sense of the next clause "from photograph to browning photograph they blacken headlines"- referring to the newspapers held by the indicated lovers to remember their loved ones who died. The later would be perhaps imagery, but what of the first?     From behind the moon boys' graves   bleed endlessly; from photograph   to browning photograph they blacken   headlines, stranded outside of time   at the story's frigid edge.   I wouldn't call this metaphor because two objects aren't being compared, rather they are being described. Yet I wouldn't call it imagery because she isn't describing the scene, but instead the very nature of her subjects.  Would this be metonymy, ambage, or something else?


In the Walking Dead, where and when did the infection start?

Where and when did the infection start? I'm curious because it isn't explained in The Walking Dead. If it was then I will have to start it all over again.


Let $f:V\times V \rightarrow \Bbb C$ be a bilinear form in a finite inner product space. Will there always be a single linear transformation $T:V\rightarrow V$ for which $f(v,u) = \langle Tv,u\rangle$ for each $v,u\in V$. If not - what's an example of this not happening?  (I can prove this for bilinear forms $f:V\times V \rightarrow \Bbb R$, but can't see if the same applies to $\Bbb C$).


How to press insert on a keyboard without numpad or insert

Hello I have a mini gaming keyboard (60%) how can i press Insert? it doesn't have that key


Record date when command was executed in the terminal?

bash_history lists only the previous commands executed.  Is it possible to record the times ie. date when they were executed?


bash - zip multiple files, take argument from variable, one of them has space in name

I want to zip file.txt and file with spaces.txt. I need to keep them in one variable. I can concat these string like this:  files="$files \"$newfilename\""   Then I have all the file names in one variable, separated by space and each one covered with quotation marks. "file.txt" "file with spaces.txt"  so I need to zip them now. However If I do:  tar czf output $files   then bash will produce:  tar czf output '"file.txt."' '"file' with 'spaces.txt"'   If I do  tar czf output "$files"   then bash will do:  tar czf output '"file.txt." "file with spaces.txt"'   In first case, bash insert a apostrophe after and before each word, in the second case, tar takes both files as one name. What should I do to produce tar czf "file.txt" "file with spaces.txt" if I have exactly this string in $files variable?


Votes display under Linked Questions is broken

I've noticed this only on MSE; the number of votes under the linked or related sections gets displayed in more than one rows if the number of votes exceeds 99 votes (two digits):    and    Using Google Chrome Version 34.0.1847.132 on Debian


What equations of general relativity and quantum mechanics are we trying to unify?

In other words, what equations hold the most promise in this endeavour? Are we all looking at the same equations or is this pursuit subjective?


Compute eigenvalue of a $4\times4$ matrix with all entries $1$

I have the following matrix, call it A: $\begin{bmatrix} 1 & 1 & 1 & 1 \\ 1 & 1 & 1 & 1 \\ 1 & 1 & 1 & 1 \\ 1 & 1 & 1 & 1 \end{bmatrix}$ I need to find its eigenvalue using its characteristic polynomial. I already did this on smaller matrices which were comfortable to calculate. But calculating an eigenvalue for this matrix seems too complex - Possibly there's a better method?  Edit: This needs to be done without an external help (e.g. Wolfram Alpha).


Reconnect an external HDD after proper ejection

After I "properly eject" an external HDD or USB stick, can I "reconnect" it without physically unplugging it?


Prevent SIGINT from interrupting function call and child process(es) within

Consider the following script:  #!/bin/bash  set -o pipefail set -o history  trapper() {    func="$1" ; shift    for sig ; do       trap "$func $sig" "$sig"    done }  err_handler () {   case $2 in     INT)        stop_received=1     ;;     TSTP)     ;;     ERR)        if [[ $2 != "INT" ]]; then # for some reason, ERR gets triggered on SIGINT           code=$?           if [ $code -ne 0 ]; then              echo "Failed on line $1"              echo "$BASH_COMMAND returned $?"              echo "Content of variables at the time of failure:"              echo "$(set -o posix; set)"              exit 1           fi        fi     ;;   esac }  main() {    ping -c 5 www.google.com # this is a test to see if INT interrupts main()    # do a bunch of stuff, I mean a real bunch of stuff, like check some    # files, do some processing, connect to a database,    # do more processing, move some files around, you get the drift }  exec > >(tee -a my.log) exec 2>&1  trapper 'err_handler $LINENO' INT TSTP ERR while main do   if [[ "$stop_received" == "1" ]]; then      break   fi   setsid sleep 2 & wait done trap ERR   What I am trying to accomplish is to run the script in an infinite loop until either the function main() returns some non zero value, i.e. some error occurred, or SIGINT is received.  However, I don't want SIGINT to stop main() from executing, in other words, if the script receives a SIGINT, it should wait for main() to finish, then exit nicely. But when I hit CTRL+C, I can see that ping is interrupted. At the moment I commented out everything under main() just to see if this works. Since ping gets interrupted, I am assuming other commands under main() would also get interrupted. When ping is interrupted, the processing jumps to the line where I check if $stop_received=1 and then the loop breaks and the script quits. If I replace the break with just an echo, then the script just continues on to the next iteration of the while main loop.  How can I stop SIGINT from interrupting the currently running command(s)? Since my script does a bunch of stuff, including DML statements in a database, interrupting main() would cause lot of grief.  Secondly, the script does not trap ctrl+z either. Or rather, the script just gets stuck on ctrl+z requiring a kill pid to terminate. I assumed that sleep being a child of bash as opposed to the script itself, ctrl+z would cause the script to pause, leaving sleep in limbo land. Hence the setsid and wait on sleep, but it still hangs.  thanks.


Why is uncommon geometric houses expensive to make?

I was making a heptagonal miniature house and wanted to research why they are so feasible. However, the Internet does not have anything over the specific question. How much exactly would it cost for one to make a heptagonal or seven sided house compared to a regular house? Why is it so much more expensive than a regular house? It has a better volume to put more housing material into it than a regular one.


I have a data table like this in excel:  ColA     ColB A        1 A        2 B        2 B        3 C        4   In a different sheet, I am trying to create two column for which the values will be drop down, using the validation.  For each row of this sheet, the first column will need to be the unique values from ColA, i.e. {A, B, C}, and depending on what was selected there, I want the second column to be presented only with the acceptable choices, i.e. if A is selected, the drop down would show {1, 2}, if B is selected, the drop down would show {2, 3}, ...  Any ideas? I feel I need a function in the validation selection that would return a subset of a list based on a selection criteria, like a SELECTIF ... All the functions I find are aggregate functions that have a nice if version (e.g. COUNTIF, ...)  I prefer to do this without VBA.  Thanks


How to return a list from a function for a "select... IN.." statement

I wish to write a function for an ERP system that returns a list that can be used in a "select...IN" statement.  For example...  instead of...  "select * from A where b in ('c','d','e')"  I need something like...  "select * from A where b in (get_items('a'))"    I've tried a function that can create the 'c','d','e' bit, but that doesn't give me any results.  I've tried several methods, but I can't seem to hit upon the right idea.  I'm okay with writing API's/functions, but what's the best method to get a list of items out of a function and into that select statement?  would an array or a sys refcursor work?


Appending variable that is modified in a for loop doesn't work as expected

I have this code:  lst = [] given = [1, 2, 3, 4, 5] result = []  for item in given:     lst.append(item)     print(lst)     result.append(lst)  print(result)   My expected result is [[1], [1, 2], [1, 2, 3], ...], but displayed result is [[1, 2, 3, 4, 5], ...] with 12345 repeated 5 times. What is wrong?  lst printed is as expected, which is [1] for the first loop, [1, 2] for the second loop, and so on.


Is there a notion of the product of confidence bands?

Given two confidence bands, it seems natural to consider the confidence band of the product of these two distributions. Does this have a name? Are there any reference that might be helpful regarding this notion?  Edit: Assume that the errors of the first, say, regression curve are not correlated with the errors of the second.


Full statement: If $a, b, c > 0$ and $a+b+c = 6$, Find the minimum value of $(a+\frac{1}{b})^2 + (b+\frac{1}{c})^2 + (c+\frac{1}{a})^2$ I've found this problem online, to me it seems like a typical olympiad inequality problem. However, I wasn't not able to solve it, at least correctly. I tried using the AM-GM inequality directly, but I think I did a mistake in that approach or the approach itself is incorrect since I got the minimum to be 432, which is obviously false and easily proved so by a direct calculation.


char!=(signed char), char!=(unsigned char)

The code below compiles, but has different behavior for the char type than for the int types.  In particular     cout << getIsTrue< isX<int8>::ikIsX  >() << endl;    cout << getIsTrue< isX<uint8>::ikIsX  >() << endl;    cout << getIsTrue< isX<char>::ikIsX  >() << endl;   result in 3 instantiations of templates for three types: int8, uint8 and char. What gives?  The same is not true for ints: int and uint32 which result in the same template instantiation, and signed int another.  The reason seems to be that C++ sees char, signed char and unsigned char as three different types. Whereas int is the same as a signed int. Is this right or am I missing something?  #include <iostream>  using namespace std;  typedef   signed char       int8; typedef unsigned char      uint8; typedef   signed short      int16; typedef unsigned short     uint16; typedef   signed int        int32; typedef unsigned int       uint32; typedef   signed long long  int64; typedef unsigned long long uint64;  struct TrueType {}; struct FalseType {};  template <typename T> struct isX {    typedef typename T::ikIsX ikIsX; };   // This  int==int32 is ambiguous //template <>            struct isX<int  >    { typedef FalseType ikIsX; };  // Fails template <>            struct isX<int32  >  { typedef FalseType ikIsX; }; template <>            struct isX<uint32 >  { typedef FalseType ikIsX; };   // Whay isn't this ambiguous? char==int8 template <>            struct isX<char  >  { typedef FalseType ikIsX; }; template <>            struct isX<int8  >  { typedef FalseType ikIsX; }; template <>            struct isX<uint8 >  { typedef FalseType ikIsX; };   template <typename T> bool getIsTrue(); template <>           bool getIsTrue<TrueType>() { return true; } template <>           bool getIsTrue<FalseType>() { return false; }  int main(int, char **t ) {    cout << sizeof(int8) << endl;  // 1    cout << sizeof(uint8) << endl; // 1    cout << sizeof(char) << endl;  // 1     cout << getIsTrue< isX<int8>::ikIsX  >() << endl;    cout << getIsTrue< isX<uint8>::ikIsX  >() << endl;    cout << getIsTrue< isX<char>::ikIsX  >() << endl;     cout << getIsTrue< isX<int32>::ikIsX  >() << endl;    cout << getIsTrue< isX<uint32>::ikIsX  >() << endl;    cout << getIsTrue< isX<int>::ikIsX  >() << endl;  }   I'm using g++ 4.something


I wanted to know is, is it violate any rules if I wrote a blog post for a given question and post it as a answer for that question.  There might be many reasons that answer is more suited as a blog post, like answer can be too long, have strong links to previous set of posts, etc.


Editing GRUB to avoid grubrescue after deleting original OS

I deleted Parrot and Ubuntu is hd2,gpt2  This screenshot shows what happens when I boot now.   what should I do to make Ubuntu default?


Is it better to take time answering a question or to answer quickly and edit?

I have been on StackOverflow for about a month now and I am noticing a pattern. The faster you get your answer in, the more chance you have of getting it upvoted. Even if it is not complete. And generally the more votes your gets, the better chance it has of being accepted.  I initially tried to post quality answers but got tired of my answer being lost to the multitude of similar answers that get thrown in before hand. Only after they have added their one-liner, do they then edit it to add links and examples.  My question is this, is this the way that the site works? Like a flock of birds going after a seed? Does speed really matter more than quality?


Give a non-admin windows account admin access except for changing a specific file

I need to give a non-admin account most admin permissions except for modifying system files. I'd like that admin account to retain all normal admin permissions but not be able to modify the hosts file. I've written a , and I'd like to do something similar in Windows 10.  The best solution I've found is to make something like this script start when the user logs in.   #Specify the file name $fileName = "C:\Windows\System32\Drivers\etc\hosts"  #Open the file in read only mode, without sharing (I.e., locked as requested) $file = [System.io.File]::Open($fileName, 'Open', 'Read', 'Read')   I understand that it won't be bullet proof, but I would like something that makes it sufficiently inconvenient to modify this file.


Let $G$ be a group. Let $H$ and $K$ be two subgroups of $G$ and $K$ is normal in $G$. Show that $K$ is normal in $HK$. My attempt: We will prove that: \begin{equation*}     \forall z \in HK, \forall k \in K, zkz^{-1} \in K     \enspace . \end{equation*} Let $k \in K$. Let $z=h'k' \in HK$. \begin{equation*}     zkz^{-1} = h'k'k(h'k')^{-1}=h'k'k(k')^{-1}(h')^{-1}     \enspace . \end{equation*} Yet, $\forall k, k' \in K, \enspace k'k(k')^{-1} \in K$. Furthermore, by assumption, $K$ is normal in $G$ and $H$ is a subgroup of $G$. Therefore, $K$ is normal in $H$. So, \begin{equation*}     h'(k'k(k')^{-1})(h')^{-1}  \in K     \enspace . \end{equation*} which implies that: \begin{equation*}     zkz^{-1} \in K     \enspace . \end{equation*} In conclusion, $K$ is normal in $HK$. I'm really not sure about the fact that $K$ is normal in $H$. Could you confirm it?


How to download all images with the full resolution (i.e. svg) from a single wikipedia article

I was asking myself how to download    all (.svg) images  from a single wikipedia article    without doing it manually for each single image. Wikipedia is offering images in different resolutions and several formats using a more complex looking url-scheme  Example url:


Showing  =nZ is a prime ideal of Z IFF n is a prime

Question: If n is an integer greater than 1, show that $\left \langle n \right \rangle=n\mathbb{Z}$ is a prime ideal of $\mathbb{Z}$ IFF n is a prime.  I have a bit of problem proving the only if condition is true.  Attempt:  Suppose $\left \langle n \right \rangle$ is a prime ideal of R. Then $a.b \in \left \langle n \right \rangle$. It is thus true that $a \in \left \langle n \right \rangle \text{or} b \in \left \langle n \right \rangle$ Any hints is appreciated. Thanks in advance.


Failed to Copy SDE Dataset Error 000260 Using arcpy.Copy_management and arcpy.env.overwriteOutput = True

I thought I could use the arcpy.env.overwriteOutput = True to overwrite the existing datasets within my target SDE "JeffCoGIS.sde"; however, I get an error that states:   ExecuteError: ERROR 000260: Failed to copy Database Connections\GISData.sde\GISData.DBO.GIS_Dept into Database Connections\JeffCoGIS.sde\GISData.DBO.GIS_Dept ERROR 000260: Item with the same path name already exists. Failed to execute (Copy).  I am new to python and couldn't find any help in ESRI Resources on how to overwrite the datasets.  Some have mentioned to use replication; however, for our particular workflow, we need to pursue overwrite and copy, if I can get it to work.    Is there a different tool I should use?  If I run this script on the empty SDE, it works fine - just when trying to overwrite the existing datasets.  #Name:  Copy_JeffCoGIS_Rev2.py #Copy all datasets including the feature classes within each dataset from #    SDE database "GISData.sde" to SDE database "JeffCoGIS.sde" import arcpy arcpy.env.overwriteOutput = True arcpy.env.workspace = "Database Connections\\GISData.sde"  fcList = arcpy.ListDatasets() #print fcList  for dataset in fcList:     arcpy.Copy_management(dataset, "Database Connections\\JeffCoGIS.sde\\"+      dataset)


Scaling and importing from blender to unity

When I make a 3d model in blender and import it to unity the model has an incorrect size and im thinking the problem has to do with the units but I don't know what units to use while modeling in blender (cycles).  Another problem is that when I import it into unity it imports itself without textures so im thinking it has something to do with how I save the model in blender, right know im saving it as .blend  And the final problem is that when I import the model from blender to unity the y,x,z axis are inverted or weird.  Thank's in advance.


I am looking for a list of standard LaTeX macros which are symbols and available without any packages. Macros like:  \LaTeX, \TeX, \slash, \textbackslash, \dots   Is there a list for such macros?


Is it safe to install Ubuntu 12.04 alongside windows 7?

Is it safe to install ubuntu alongside windows 7?  I have a laptop with 500 GB hard disk and 2 GB RAM and it is pre-installed with windows 7.My professor asks me to install ubuntu 12.04 alongside Windows 7.  However I am not sure whether it is safe to make a dual boot system? Will it affect my hard disk ?Is there any chance of a hard disk crash?  Please help.


How can I remove these apps from my device?

I am trying to remove the Facebook and Messenger apps from my Asus Zenphone Laser 2.  Unfortunately, in both cases, I seem to be unable to find the option to fully delete them from the device. I have disabled them, but the app management screen now shows the following:     How can I fully delete/uninstall them?


How do I drive 12 strings of 12 leds each?

I would like to drive 144 leds with a battery power supply. I want to drive all the leds all the time. 12 leds in series on each string.  The Led specs are:   PD 100 mW Max.  VR 5 V IAF 25 mA IPF 85 mA VF at 20mA 1.8 Typ, 2.1 Max IR at 5V 100 uA   Where do I start for something with a low cost?


Why Is $1^{\infty}$ an indeteminate form?

For me, multiplication is a binary operation so it can be applied only on a finite sequence of numbers. but $1^{\infty}$ requires that we apply multiplication infinitly which is not defined as multiplication is a binary operation.  Is that a good reason? If not, what is the reason?   If my reason is ok, So similarly, $5^{\infty}$ is indeterminate ?   ِAdded:   I noticed that all answers are in context of "limits". Algebraically, multiplication is a binary operation, So it ONLY can be used to define multiplication of finite sequence of numbers as not a infinite sequence. So algebraically, what does $1^{\infty}$ even mean?


I am working on JSON-LD schema for SEO purpose and stuck at @id. What type of value can I use? Or is there anything specific value that should I use? Or How it is works? Or How much it is useful? It is totally confusing for me. <script type="application/ld+json"> {    "@context":"https://schema.org",    "@type": "GiftShop",    "name": "Example Showcase",    "@id": ""    "url": "https://example.com/" } </script>


I sometimes want to make use of black operators corresponding to \Box and \Diamond. \blacksquare is a good blackened version of \Box, but \blacklozenge does not have quite the same shape as \Diamond. Are there other fonts I can access to resolve the problem?  No, \blacklozenge does not have the same shape as \Diamond and the question referred to has other concerns than mine.


Use the division algorithm to prove that 3|(n³ + 2n) for all n ∈ ℕ

I can do it by induction, thanks to the wonderful people of this website, but I'm not sure how to do it by the Division algorithm. Can anyone help me? I think I can show how 3 divides 2n, but I'm not sure how to show that 3 divides n³.


Can't reasonably complete a low quality question review

I looked in the low quality review queue (there was a 1 on it).  Turned out to be a question.    That is certainly not a looks good.  I've already added a comment before it hit the queue (and have the only comment there at all).  Its not an edit I can save.  And .  The only possible answer is skip.  If this is the case, I don't believe I should have seen the review in the first place.  Given that:   I already commented on the question have no close votes   These two criteria should have the question not show up in the review queue because there is no action I could reasonably take.  You might say that 'Edit' is an action, but I believe that the fact that I've previously seen (and commented on) the question means that I don't have any idea of an edit to make to fix it.  (Aside: I am curious if it would have hit my low quality review queue if I had previously cast a close vote on it)  Yes, I know this is not the easiest thing to reproduce, but its there and can be reproduced in the right circumstances.


\renewcommand being ignored when babel is loaded

my Problem is, as will be shown in the following 2 MWEs, that the custom column names i specified for my glossary, will be overwritten when babel ist loaded. The associated .bib file can be found at the end. How can i prevent this behaviour? I already treid altering the position of the \renewcommand prompts. First without babel loaded: \documentclass[english, a4paper, 11pt, DIV=calc, headsepline, titlepage, bibliography=totocnumbered]{scrartcl} \usepackage[T1]{fontenc} \usepackage[utf8]{inputenc} \usepackage{siunitx} \usepackage[record, abbreviations, symbols, nonumberlist, hyperfirst=false, toc=false, stylemods={longextra}]{glossaries-extra} \glsaddstoragekey{unit}{}{\glsentryunit}  \GlsXtrLoadResources[     src={bibfiles/symbols}, % data in symbols.bib     sort-field={name}, % sort by name field     sort={letter-nocase}, % case-insensitive letter sort     type=symbols, % put these terms in the symbols list     field-aliases={unit=symbol},% convert unit key to symbol     save-locations=false % don't save location lists ] % change column headers: \renewcommand{\entryname}{Symbol} \renewcommand{\symbolname}{Unit} \renewcommand{\glslongextraSymbolAlign}{l}  \begin{document}  \printunsrtglossary[type=symbols, style={long-name-sym-desc}]  \end{document}  The result is exactly how i want it to be:  Now when babel is activated as so: \documentclass[english, a4paper, 11pt, DIV=calc, headsepline, titlepage, bibliography=totocnumbered]{scrartcl} \usepackage[T1]{fontenc} \usepackage[utf8]{inputenc} \usepackage{babel} \usepackage{siunitx} \usepackage[record, abbreviations, symbols, nonumberlist, hyperfirst=false, toc=false, stylemods={longextra}]{glossaries-extra} \glsaddstoragekey{unit}{}{\glsentryunit}  \GlsXtrLoadResources[     src={bibfiles/symbols}, % data in symbols.bib     sort-field={name}, % sort by name field     sort={letter-nocase}, % case-insensitive letter sort     type=symbols, % put these terms in the symbols list     field-aliases={unit=symbol},% convert unit key to symbol     save-locations=false % don't save location lists ] % change column headers: \renewcommand{\entryname}{Symbol} \renewcommand{\symbolname}{Unit} \renewcommand{\glslongextraSymbolAlign}{l}  \begin{document}  \printunsrtglossary[type=symbols, style={long-name-sym-desc}]  \end{document}  i will get the following:  Associated bib file: % Encoding: UTF-8  @symbol{alpha,   unit= {\si{\radian\per\second\squared}},   name = {\ensuremath{\alpha}},   description = {angular acceleration} }  @symbol{x,   unit = {\si{m}},   name = {\ensuremath{x}},   description = {position} }  @symbol{v,   unit = {\si{\metre\per\second}},   name = {\ensuremath{v}},   description = {velocity} }  @symbol{a,   unit = {\si{\metre\per\second\squared}},   name = {\ensuremath{a}},   description = {acceleration} }  @symbol{t,   unit = {\si{s}},   name = {\ensuremath{t}},   description = {time} }  @symbol{F,   unit = {\si{N}},   name = {\ensuremath{F}},   description = {force} }


How can I play a new character with the same progress as my old one?

Is there a way to play with another character without having to start all over again in Borderlands 2?


Show following series diverges $1/(log2)^p + 1/(log3)^p + 1/(log4)^p ... + 1/(logn)^p +...$

Show that following infinite series diverges for $p \ge 0$  $\displaystyle \frac{1}{(\log 2)^p} +\frac{1}{(\log 3)^p} +\frac{1}{(\log 4)^p} +\cdots +\frac{1}{(\log n)^p}+\cdots$


Cardinal of all well-orders of $\mathbb{N}$

Lets consider the set  $$ A = \{R\subset\mathbb{N}^2:R \text{ is a well-order of } \mathbb{N}\} $$ Now, it's clear that $\aleph_1\leq|A|\leq2^{\aleph_0}$(Since all the well-orders of $\mathbb{N}$ are isomorphic to some $\alpha<\aleph_1$ which gives $\aleph_1\leq|A|$ and every well-order of  $\mathbb{N}$ is a subset of $\mathbb{N}^2$, of which there are $2^{\aleph_0}$, giving $|A|\leq2^{\aleph_0}$)  If we were to assume the  then it clearly follows $|A|=\aleph_1=2^{\aleph_0}$(By Cantor-Berstein theorem)  However in ZFC, I'm not sure how to procced, I think that $|A|=2^{\aleph_0}$, but I do not know how to prove this or if this is right. Any idea on what to do?


just want to clear something up. Take a ball that's been dropped to the ground. Gravity acts and this ball as it has mass and then the ball now moves to the ground with a constant force of say ($X$). Now when the ball makes contact with the ground, Newtons 3'rd Law takes effect (no air resistance): If object A (the ball) exerts a force on object B (the floor), then object B will exert an equal force on object A in the opposite direction. (Action has equal opposite reaction). Now here's where I get confused. If the ball (which has a constant force when it hits the ground ($X$)) experiences the same constant force in the opposite direction ($-X$, minus indicating opposite direction), then the total force acting on the ball should be net ZERO ( $X + (-X) = 0$). So there are no net forces acting on the ball, so why does it BOUNCE BACK? What am I missing? Shouldn't the ball just stay on the ground? Bouncing back means a force greater than (-X) was applied to the ball giving it upward motion. Where did it come from?


Why do floating-point calculations have rounding error

While I'm fairly aware of the fact that floating-point calculations suffer sometimes from accuracy issues, I'm not aware of the scientific reason behind it. To be precise, I'm not aware why some apparent straightforward roundings sometimes fail to be executed correctly.  behave weird enough which makes me wonder whether a fair explanation exists:  alert(0.57 * 10000); // this is supposed to be 5700 alert(10 / 3); // this is supposed to be 3.33333333 (why the 5 at the end) alert(2.34 / 100); // this is supposed to be 0.0234 (why the 7 at the end)    popular article discusses floating points in details. I'm going to quote from it the following paragraph which looks like an explanation to my question. However, I was not able to understand what the paragraph wants to say:     Since rounding error is inherent in floating-point computation, it is important to have a way to measure this error. Consider the floating-point format with  = 10 and p = 3, which will be used throughout this section. If the result of a floating-point computation is 3.12 × 10-2, and the answer when computed to infinite precision is .0314, it is clear that this is in error by 2 units in the last place. Similarly, if the real number .0314159 is represented as 3.14 × 10-2, then it is in error by .159 units in the last place. In general, if the floating-point number d.d...d × e is used to represent z, then it is in error by d.d...d - (z/e)p-1 units in the last place.4, 5 The term ulps will be used as shorthand for "units in the last place." If the result of a calculation is the floating-point number nearest to the correct result, it still might be in error by as much as .5 ulp. Another way to measure the difference between a floating-point number and the real number it is approximating is relative error, which is simply the difference between the two numbers divided by the real number. For example the relative error committed when approximating 3.14159 by 3.14 × 100 is .00159/3.14159 - .0005.   In short, while the regular Windows calculator computes everything correctly, why can't JavaScript engines behave the same way?


When I install binwalk with apt-get install binwalk in Ubuntu 18 I get version 2.1.1 even in  there is version 2.2.0. long time ago. why binwalk didn't update in ubuntu repository?   By the way, why I can't install those project with apt-get?     Who is decided to enter then to Ubuntu repository?


How to get list of files with not having search string

I have a requirement to display all files in a directory which doesn't have CountOfFilesTransmitted=0 string in them.   If I give below command it gives only those files which has CountOfFilesTransmitted=1  find . -type f | xargs grep -l "CountOfFilesTransmitted=1"   Gives: 1.log, 2.log, 10.log  find . -type f | xargs grep -l "CountOfFilesTransmitted=1" -- gives 3.log, 7.log   There are logs in that directory with 0 to 100 files Transmitted I have to give 101 entries. Is there a way to get filenames which have non zero?  something like "find . -type f | xargs grep -l "CountOfFilesTransmitted!=0" which should return all files which doesn't have "CountOfFilesTransmitted=0" string.


I use the smartphone USB dethering internet.  The same is true when connecting through an internal router.  Only the internal network IP is found, and the real IP is not visible.  How can i find it.  ifconfig  enp0s20f0u3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500         inet 192.168.42.228  netmask 255.255.255.0  broadcast 192.168.42.255         inet6 fe80::1e25:40f2:93d6:20fa  prefixlen 64  scopeid 0x20<link>         ether 42:39:19:9d:ea:b3  txqueuelen 1000  (Ethernet)         RX packets 8831  bytes 6881241 (6.8 MB)         RX errors 3  dropped 0  overruns 0  frame 3         TX packets 7230  bytes 1269771 (1.2 MB)         TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0  enp4s0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500         ether f4:8e:38:ee:82:17  txqueuelen 1000  (Ethernet)         RX packets 0  bytes 0 (0.0 B)         RX errors 0  dropped 0  overruns 0  frame 0         TX packets 0  bytes 0 (0.0 B)         TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0  lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536         inet 127.0.0.1  netmask 255.0.0.0         inet6 ::1  prefixlen 128  scopeid 0x10<host>         loop  txqueuelen 1000  (Local Loopback)         RX packets 2002  bytes 137278 (137.2 KB)         RX errors 0  dropped 0  overruns 0  frame 0         TX packets 2002  bytes 137278 (137.2 KB)         TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0


Do we auto-detect and highlight CSS for questions tagged CSS?

Wasn't sure why this suggested edit was necessary.  The only tag is  so I thought this should be picked up by our algos.  Tagging as bug but it may be a feature request.


How many 4 digit numbers are there which contains not more than 2 different digits?  My attempt   total no. of digits -  the digits which have all different digits.  i.e (9.10.10.10)-(9.9.8.7)=4464  But the answer is 576..What am i missing..Is there any other way to solve this.?


How to set a personalized port as default in Apache?

My website work only if I run:     domain.com:44400   How to set port 44400 as the default in Apache?  I need have access by domain.com not domain.com:44400


Prove zeta function has coninuous derivatives of all orders

I need to prove that the $\zeta$ function $$\zeta(x):=\sum^{\infty}_{k=1}\frac{1}{k^x}$$defines a function that has continuous derivatives of all orders.  Here's my attempt:  So, the $n$'th derivative is $$\frac{(-1)^n\ln^n(k)}{k^x}$$  So, we can see that this is continuous on $x\in(1,\infty)$ and that the partial sums $\zeta_s(x)=\sum^s_{k=1}\frac{(-1)^n\ln^n(k)}{k^x}$ are finite, so hence the function has continuous derivates of all orders.  Is this enough/correct?


How do I prevent fake sessions on my Google Analytics?

In Google analytics I freqently experience what I am calling "SEO attacks", where a single visitor or entity visits all or may of the links on my website, but somehow resets the session for each page, making the bounce rate look incredibly high even though I have had a "large amount" of visitors. Even though there are "multiple" visits I know it's one entity (person, machine, company?) because I currently have very low website traffic and when these spikes in activity happen they stand out very strongly. As well, the behavior for each "separate" visit is exactly the same, though they view multiple pages (for example, they all bounce 100%, or they visit the page 3 times, or they all have a 20 second time on page). Screenshot below:  Sometimes it's 20 "sessions", sometimes it's 100, sometimes it's 300. The only semi-solution I have for the problem is to go through and delete every individual user, but that takes a lot of time. Has anyone else had this type of problem? Does anyone else know how to prevent it?


Split disconnected polygons into separate features after using clip tool?

I'm working with a series of forest polygons (geodatabase feature classes), which I'm trying to clip to an area with a specific land use history (marked as "undisturbed" in the screenshot below)in ArcGIS 10.3.1. I'm then hoping to filter out all polygons less than 1 hectare for additional analysis.   My problem is that some of of the forest polygons ("cove_ecogroup" below) overlap the larger land use polygon in multiple areas, which leaves me with some disconnected features in my output. This is fine, except that it makes my 1-hectare filter impossible because these shapes are being stored as larger than they actually are because they retain the FID of the original feature instead of splitting into multiple new features (See image 2).  Is there a way to split these into multiple features so that I can filter out everything under 1 hectare? This analysis covers hundreds of thousands of acres, and so I won't be able to edit each new polygon individually.


“Is there a way you could/would accept?”

Is it correct to write this in a formal letter:     My certificate is not valid anymore. Is there a way you could accept my expired certificate?"   Or should I use would instead of could? And what is the difference between those two?


Any pointers on getting a 75% hydration wheat sour dough loaf to hold more shape and spread less?  Full details of current method:  I have a 100% wheatflour levain with a 75% hydration. It is stiffer than most I see online but grows well. It lives in the fridge all week until I make a loaf. It then gets fed with 40 g flour per 30 g of water and left to expand.  I then make a kilogram loaf using 400 g flour and 300 ml water. This is vigorously kneaded for 10 minutes by hand or a good 5 minutes by a Kenwood Chef Mixer with the dough hook.  After being left for an hour in a moist environment then folded and added to a cane banneton it is left untouched until it has expanded by varying amounts (somewhere between 50-100 % extra in volume).  It is only touched once more when the oven is preheated -it is turned out onto a silicone sheet on an oven tray and then placed on a preheated, upturned glass dish to warm the bottom of the loaf. It's then baked in an oven at 220 C for ten minutes and then 200 C for another 30 minutes.  Invariably, the loaf produced is very flat compared to the banneton with a nice crumb and flavour. The crumb is stretchy and a little chewy.    I have tried adding less water than this with similar results. This loaf was proved in fridge overnight and baked in the morning. The loaf looks similar when proved at room temperature over shorter durations.    All I want is to produce similar results except the bread holds its shape more and produce a taller. Any tips?  As my partner and I only eat one loaf per week it's a slow trial and error process varying hydration and watching for expansion.


Prove that the additive group $ℚ$ is not isomorphic with the multiplicative group $ℚ^*$. Prove that $ℚ^*_{>0}$ is not isomorphic with $ℚ$.


Can a sequence which decays more slowly still yield a converging series?

In Bergman's companion notes to Rudin, he says that "If a sequence of positive terms has convergent sum, so does every sequence of positive terms which decays more rapidly." So given a sequence $\{a_n\}$ of positive terms such that $\sum_n a_n$ converges, if $\{b_n\}$ is such that $$ \lim_{n\to\infty} \frac{a_n}{b_n} = +\infty, $$ then $\sum_nb_n$ converges. I can prove this given $\{a_n\}$ and $\{b_n\}$. However, can we find $b_n$ which decays more slowly, i.e. $$ \lim_{n\to\infty} \frac{b_n}{a_n} = +\infty $$ such that $\sum_n b_n$ converges?  Similarly, we have the claim "if a sequence of positive terms has divergent sum, then so does every sequence of positive terms which decays more slowly."


Remove Punctuation When Checking for Duplicate Titled Questions

I recently saw a question titled "" (10k+ users only). I thought, "surely someone has asked this question before", and began looking for a duplicate.  is a question with the exact same title, just with a little different punctuation and casing. It was "Jquery vs Javascript" and "jQuery vs. Javascript?". The only difference being the ., ?, and the casing.  Since we now , I propose that when checking for questions with duplicate names, certain punctuation be striped out to prevent the duplicate from occurring in the first place.  As pointed out in the comments, if isn't already, white-space and non-printable characters may want to be removed for duplicate detection as well.


Find the equation of the tangent line to $y=x^4-4x^3-5x+7$ at the point (1,-1)  I'm completely at a lost for this problem. Am i going to use $\frac{f(x+h)-f(x)}{h}$ formula?  Please Help!!!


I have a simple objective: Keep NumLock always on   and : Linux Mint 17.3 / 18 Cinnamon  I found this:    So, I created this small script  -rwxr--r-- 1 root      root      47 Apr 15 07:50 keep-numlock-on.sh   with content  #!/bin/bash xmodmap -e 'keycode 77 = NoSymbol'   and I added it to sudo crontab -e like this  @reboot /home/vlastimil/Development/bash/keep-numlock-on.sh   To my surprise, it does not work on reboot and I have no clue as to why.  It works if I manually call the script.  Any help appretiated.  Further attempts:  I created this file in ~/.config/autostart  -rw-r--r-- 1 vlastimil vlastimil 308 Apr 15 10:00 NumLock.desktop   with content  [Desktop Entry] Encoding=UTF-8 Name=Keep NumLock always on GenericName=Keep NumLock always on Comment=Keep NumLock always on Exec=/home/vlastimil/Development/bash/keep-numlock-always-on.sh Icon= Terminal=true Type=Application Categories= X-GNOME-Autostart-enabled=true Hidden=false X-GNOME-Autostart-Delay=0   while renaming the script and changing rights to  -rwxrwxrwx 1 vlastimil vlastimil 47 Apr 15 09:56 keep-numlock-always-on.sh   in order to rule out permission issue.  Well, I don't know what I did wrong, but it still does not work :(  EDIT1:  As for the comments, I changed the contents of the script to:  #!/bin/bash /usr/bin/numlockx on DISPLAY=":0" xmodmap -e 'keycode 77 = NoSymbol'   But without luck. This is really annoying to me. Please help and if you solve it, you will be rewarded with 50 points. Thank you.  EDIT2:  sudoedit /etc/X11/xinit/xinitrc   and placed the path to the file in there, still no luck.  . /etc/X11/Xsession /home/vlastimil/Development/bash/keep-numlock-always-on.sh     EDIT3:  xmodmap messes up with my keyboard mappings, making it unusable for this purpose.


I found a sentence in :     "Another example: You work in a kindergarten, and one day a child starts to walk in a strange way, and saying he broke his legs. You examine and find nothing wrong. Then you can reasonably infer that one of his parents broke their legs, since children then often actuate as described,"   I thought this should be corrected to be:     "Then you can reasonably infer that one of his parents broke his/her   legs,"   And logically "legs" should be leg(s) given that if one walks in a strange way it doesn't necessarily mean that his/her two legs are hurt.


Dual-booted system: How much space should I allocate for /, /home, and /swap?

I recently set up a dualboot with Ubuntu 17.04 and Windows 10 (Home 64). My system came with 8GB of RAM and 512GB of SSD. I followed some tutorials and most of them recommended a 15-25GB partition to install Ubuntu, regardless of the available space on the hard drive or SSD. Here's the partition breakdown:  Ubuntu partition: 25GB, the OS takes up about 5GB and I allocated 10GB for swap space Windows (C:) partition: 450GB, the OS takes up about 30GB  The remaining space on the Ubuntu partition is roughly 10GB out of 25GB. I'm trying to understand the file system. So everything in /home directory and / (root) is in the 25GB partition.   How do I access (or make use of) the rest of the SSD on the primary (C:) drive which is roughly 420GB (not including Windows OS) for bulk storage (projects, assignments, etc)? Would this also be a good place to install SDKs and other developer tools & packages? Should I allocate a separate partition for this?  If this isn't the right approach, is there a way to re-adjust the partition sizes to make sure I have plenty of bulk storage? Like re-allocating space from Windows (C:) drive and adding it to /home. Looks like most people work out of the /home directory and store all their work directories there, should that partition be as big as it can?


$\mathcal A$ is empty, what is $\bigcap_{S\in\mathcal A}S$?

Given a collection $\mathcal A$ of sets and a large set $X$. What are  $\bigcup_{S\in\mathcal A}S$ and $\bigcap_{S\in\mathcal A}S$ ?  The problem is  if $\mathcal A$ is empty, what  do  $\bigcup_{S\in\mathcal A}S$ and $\bigcap_{S\in\mathcal A}S$  mean  ?   Muknres's "topology" page 12,  if $\mathcal A$ is empty, then  $\bigcup_{S\in\mathcal A} S=\emptyset$ and $\bigcap_{S\in\mathcal A}S=X$.  I 'm puzzled about this. Can someone tell me why? Thanks a lot!


I have long running process at Debian. At some point in throw an error:     Too many open files.   Running:     ulimit -a   shows:     open files                      (-n)   1024   I wish to increase number of open files in 2 times. After execution     ulimit -n 2048   the limit is active until end of my session, which is not applicable for the task.  How can I permanently increase number of open files?


How do I skip os.makedirs if the folder already exists?

I'm writing a program that needs a folder to be created in the user's Documents folder. It runs perfectly the first time it is executed but fails if it is executed more than once. I'm using the os.makedirs function and it fails because the folder already exists after the first execution. How do I skip the os.makedirs function if the folder already exists?  path = "/home/" + username + "/Documents/Keys"     try:         os.makedirs(path)         filename = "file%s.txt" % random         with open("/home/" + str(username) + "/Documents/Keys/" + filename, 'w') as f:             f.write(str(createkey) + " " + random + " " +  d)             sys.exit()     except OSError:         print "There was a problem generating the key"   Expected Result: If the folder has already been created; it should skip over the os.makedirs function, and execute the rest of the code.


What does calling a method in this way mean in Java?

I am often coming across this syntax in a Java code-base that I am going through: className.class.method() What does that mean? Is it any different from className.method()?


I'm trying some things with my shell. This includes the following command:  kill $$  My expectation was that the shell would log me out and terminate itself. But instead the bash persists without change.   Any idea why?  I ran this command on different environments (archlinux, debian). The behavior was always the same.


Triangle Inequality with Complex Numbers

I was wondering how to prove the triangle inequality with complex numbers:  Verify that the function $d(z_1, z_2)$ is a distance funtion on $\mathbb{C}$ and also on any subdomain on $\mathbb{C}$.  I finished all but the inequality, which is what I need assistance with. I don't know how to prove the distance function inequality:  $d(z_1, z_3) \le d(z_1, z_2) + d(z_2, z_3) $


I am having a difficult time trying to do something that seems like it should be really easy to do. I basically want to multiply 2 numbers in a node and then sum the total of those numbers for all the nodes. Here is the XSLT code I have tried.  <xsl:value-of select="sum(Parts/Part/Quantity * Parts/Part/Rate)"/>   This code results in an error that says "Argument 1 of function sum cannot be converted to a node set."   Does anyone have an idea of what is wrong or how I can accomplish what I am trying to do?


$M + N$ and $M \cap N$ are finitely generated $A$-modules implies $M$ and $N$ finitely generated using exact sequences

Let $0 \to M_1 \to M \to M_2 \to 0$ be an exact sequence of $A$-modules.  i) Prove: If $M_1$ and $M_2$ are finitely generated, then $M$ is too.  ii) Let $M$ and $N$ be sub-modules of an $A$-module $L$. Assume that $M+N$ and $M\cap N$  are finitely generated $A$-modules. Prove that $M$ and $N$ are finitely generated $A$-modules.  If have proved the first part, but i don't see how to do the second part. I tried to use the first part, so to find an exact sequence with $M$ in the middle and finitely generated modules in place of $M_1$ and $M_2$, but I can't find a surjective map $M \to P$ (for some f.g. $A$-module) in the sequence:  $$0 \to M\cap N \to M \to P \to 0$$  any hints/help would be appreciated.


Don't know why I am getting Null Pointer exception

Here I am retrieving data from an API everything works fine but 1. Suces is showing on Toast then App crashes   public class MainActivity extends AppCompatActivity {       public TextView textView;     @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);         textView = findViewById(R.id.textview);         MyWebService myWebService = MyWebService.retrofit.create(MyWebService.class);         Call<Train>  call = myWebService.getTrain();         call.enqueue(new Callback<Train>() {             @Override             public void onResponse(Call<Train> call, Response<Train> response) {                 if(response.isSuccessful() && response.body()!=null)                 {                      Train train = response.body();                     Toast.makeText(getApplicationContext(),"Sucess",Toast.LENGTH_LONG).show();                     textView.setText(train.getTrain2().getName());                 }             }              @Override             public void onFailure(Call<Train> call, Throwable t) {                 Toast.makeText(getApplicationContext(),t.getMessage(),Toast.LENGTH_LONG).show();              }         });     } }   I am getting error at this line  textView.setText(train.getTrain2().getName());  But I initialize the textview and also checking response!=null  Error is   02-14 22:41:40.003 1557-1557/? E/Zygote: v2 02-14 22:41:40.003 1557-1557/? E/Zygote: accessInfo : 0 02-14 22:41:41.963 1557-1557/com.piyushjaiswal121.rail E/AndroidRuntime: FATAL EXCEPTION: main     Process: com.piyushjaiswal121.rail, PID: 1557     java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String com.piyushjaiswal121.rail.Train2.getName()' on a null object reference         at com.piyushjaiswal121.rail.MainActivity$1.onResponse(MainActivity.java:36)         at retrofit2.ExecutorCallAdapterFactory$ExecutorCallbackCall$1$1.run(ExecutorCallAdapterFactory.java:70)         at android.os.Handler.handleCallback(Handler.java:739)         at android.os.Handler.dispatchMessage(Handler.java:95)         at android.os.Looper.loop(Looper.java:148)         at android.app.ActivityThread.main(ActivityThread.java:7325)         at java.lang.reflect.Method.invoke(Native Method)         at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)


Does it take energy to move something in a circle?

Work can be calculated by $W = Fd\cos\theta$ where $\theta$ is the angle between the force $F$ and the displacement $d$  Let's say there's a ball and a (physically ideal - no friction etc.) robotic arm situated in otherwise empty space. The arm takes the ball, moves it around in a circle, and then returns it exactly to where it started. The arm also returns to its starting position.  In this case, there is no displacement overall. The ball and the robot arm are in the exact same positions as when they began.  Thus, $W = F\cdot 0 \cdot \cos\theta = 0$ So no energy was required to move the ball in a circle.  However, this disagrees with my intuition, because if I were to make a robot arm that would do this, I feel like I would need to give it an energy source (for example, a battery), and that by the time the robot was done, I would have lost energy from that battery.  Does the movement require energy? If so, where did I mess up in my calculation? If not, why would my robot need a battery pack or some energy source in order to make this movement? (If it doesn't, please explain.)


We know that two black holes can merge to form a single black hole with the release of vast amounts of energy. Can the reverse happen? That is can it happen that large energy is supplied to a black hole and it splits into two?


Let $T > 0$. Let $f \colon [0, T] \to \mathbb{R}$ be a Lebesgue measurable function with \[ \int_0^T \lvert f(s) \rvert ds < \infty. \] Suppose that \[ \int_0^t f(s) ds = 0 \] for all $t \in [0, T]$. Does it hold that $f(s) = 0$ a.e. $s \in [0, T]$? I know that if we add $f > 0$ to the assumptions above, the conclusion holds. But I don't come up with a proof for sign-changing functions at the moment. We can prove the positive functions version if we notice that the inclusion $C^\infty_c [0, T] \subset L^1[0, T]$ is dense. Thus, I tried to apply this fact for sign-changing version with $f^+ = \max(0, f)$ and $f^- = \max(0, -f)$, only to find that they did not work well with my effort. Do you have a good idea to obtain a proof, or a counterexample?


How should I interpret these ACF / PACF plots for a time series?

I am trying to determine the most appropriate degree of difference to start building an arima model for this dataset. I already know that I need a first difference, but there is a seasonal component and I am not exactly sure where to go from here. I've tried several potential options but I am just not very confident when interpreting these plots. I will include the raw time series plot / acf / pacf plots as well as the first differenced time series / acf / pacf plots. Any help would be fantastic!! Original:    First Difference:


Anyone can assist me finding the cardinality of Complex Numbers and some of its subsets under ZFC?  and if we are to prove that if $\kappa$ is any uncountable cardinals, |$\omega \times \kappa$|=$\kappa$. Can it be proved by using if A $\subset$ B and if has uncountable cardinality then A has uncountable cardinality.


I see numbers next to comments but I cannot seem to do anything with them, can we enable comment voting and flagging in iOS app?


What are the recommended directory permissions?

I'm gearing up to deploy a Drupal 7 site and I can't find any documentation about what the recommended security-conscious file and directory permissions should be set to.  Specifically default/files/ (also sub directories?), settings.php, .htaccess and anything else I should be aware of.


How to create a pageview using ga() function?

I manage google analytics inside google tag manager and I don't have any separated script for google analytics in the head of my website.  I need to use ga() function like :   <!-- Google Analytics --> <script> (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){ (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o), m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m) })(window,document,'script','https://www.google-analytics.com/analytics.js','ga');  ga('create', 'UA-XXXXX-Y', 'auto'); </script> <!-- End Google Analytics -->   See? It has created ga right after google analytics script. But as I said, I don't have any script for google analytics. I have just a script (which is located in the head of my website) from google tag manager:  <script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start': new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0], j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src= 'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f); })(window,document,'script','dataLayer','GTM-{$google_tag_manager_token}'); ga('create', 'UA-{$google_analytics_token}', 'auto'); </script>   The problem is, it throws:     Uncaught ReferenceError: ga is not defined   Any idea where should I place ga('create', 'UA-{$google_analytics_token}', 'auto'); exactly?     It should be noted, when I run ga('create', 'UA-{$google_analytics_token}', 'auto'); in the console of the browser, it will be created as well. Do I need a settimeout() ?


Basic question about proofs with the goal $\exists x P(x)$

In Velleman, How To Prove It?, we learn to prove a goal of the form $\exists x P(x)$ by extracting the existential quantifier from the goal, assigning a value to an arbitrary variable x and then deriving $\exists x P(x)$ from the introduced assumption. In the example below, to prove $\exists y[y+2x=0]$ (1), we assume $y$ and assign to it the value $-2x$ (2) and derive the goal from this assumption (3).  $\exists y[y+2x=0]$ $ [y=-2x]  \rightarrow  [y+2x=0]$ $ [y=-2x]  \space \land \exists y[y+2x=0] \rightarrow  [y+2x=0]$  I really do not understand how is it possible to assume the value assignment to y as one of the givens in the proof. Is a mathetical equality logically treated as a tautology, so that it can be unrestrictedly assumed in any proof?


What does it mean "See something(3) or see something-else(5), etc..." in the man of a command in terminal?

I have a simple question I made my self but didn't find any answer and hints.  When I type for the man entries of a command, e.g. "man git", I get the following:  ...  DESCRIPTION        ...         See gittutorial(7) to get started, then see Everyday Git[1] ...        The Git User's Manual[2] has a more in-depth        introduction.         After you mastered the basic concepts, you can come back to this page to learn what commands Git offers. You can learn more about individual Git        commands with "git help command". gitcli(7) manual page gives you an overview of the command line command syntax.         Formatted and hyperlinked version of the latest Git documentation can be viewed at http://git-htmldocs.googlecode.com/git/git.html.   Could someone explain what are those "See gittutorial(7)...Everyday Git[1]...gitcli(7)" etc.? I mean, I know that they are telling "look at this resource if you want to know the basic concepts, for more info, etc.", but actually how should one interpret it? What is the meaning of the numbers (like 7, 1, 2, etc..) inside the parenthesis or brackets? And where I can find the resources the manual is telling me to see, do I have to type something in the man prompt, or search on the Internet?   I just would like to ask for an elucidation.   Thank you for your attention!


List files installed by a package on my Linux system (Ubuntu / APT)

When I install a new package in Ubuntu (using APT), like this:  sudo apt install binutils  it will install me the /usr/bin/nm utility. But it will also install other files in other locations.   Is there a way to see what files were installed by a specific package and in what locations? (Maybe see the list of files that will be installed before actually installing the package!)  I know that the reverse operation (see the belonging package for a file) can be achieved with the apt-file command.


Is there a limit to how much concise information a human can learn adequately?

Like, I am trying to learn more chemistry, but also computer programming from the higher-level programming methodologies, frameworks, languages, APIs, XML, web development, and I'm also hoping to improve especially with computer hardware/electrical engineering, and I am trying to improve my pixel art/graphic design/animation skills all at the same time, that is no set schedule for any, and just learning whatever I get my hands on.  Is it possible to learn this way for a human, or will this eventually become too much, and I'll have to sort them/order what I learn separately?  I have not been seeing very much success, but I do keep learning. The problem? Well, I can't get a good grasp on any subject because I am interchangeably attempting to learn all of the aforementioned subjects sporadically, interchangeably, and without any fine schedule. Is this a wrong way for a human to learn, or is the human brain capable of constantly & linearly learning anything in any order very well?


Smarter way to solve $ \int_0^1\arctan(x^2)\,dx$

I'm trying to solve the following definite integral: \begin{equation} \int_0^1 \arctan(x^2)dx \end{equation} I tryed first by parial integration, finding: \begin{equation} x\arctan(x^2)\Bigl|_0^1-\int_0^1 \dfrac{2x^2}{1+x^4}dx \end{equation} Then: \begin{equation} \int_0^1 \dfrac{2x^2}{1+x^4}dx=\int_0^1 \dfrac{(x^2+1)+(x^2-1)}{1+x^4}dx=\int_0^1 \dfrac{x^2+1}{1+x^4}dx+\int_0^1 \dfrac{x^2-1}{1+x^4}dx \end{equation} and i introduced the following substitution: \begin{equation} t=x-\dfrac{1}{x}\qquad s=x+\dfrac{1}{x} \end{equation} Than I used this weird substitution: \begin{equation} \dfrac{\sqrt{2}}{2}\arctan\left( \dfrac{t}{\sqrt{2}} \right)\Bigl|_0^1+\int_0^1\dfrac{ds}{(s-2)(s+2)} \end{equation} In the end simple fraction: \begin{equation} \left[\dfrac{\sqrt{2}}{2}\arctan\left( \dfrac{t}{\sqrt 2} \right)+\dfrac{1}{4}\log(2-s)-\dfrac{1}{4}\log(s+2)\right]_0^1 \end{equation} and that is the solution.  Now: does it exist a simpler path to solve this integral?


I've just finished watching the  movie and having had time to reflect a bit more on it, I still cannot understand why the government would not just send a second pod through the machine if they seriously did not believe Dr. Arroway. I mean, the thing cost what? Half a trillion dollars to build, why not use it at least a second time? Unlike religion there is actually a way to test the testimony and they do not have to take it on faith at all.  Note that I did not read the novel (yet) and I would appreciate it that if it is answered in the novel that somebody tells me.


With the commands \openout and \write I output text into a file. I want this file to have a name of containing an underscore (eg. name_01.txt), but I'm unable to get the underscore in the filename. My attempt (with \_):   \documentclass{article} \begin{document} \newwrite\tempfile \immediate\openout\tempfile="name\_01.txt" \immediate\write\tempfile{this is interesting} \immediate\closeout\tempfile \end{document}


What is the best method to deal with harassing users?  For reasons unknown I have become the target of what I believe to be an abusive user.  Within a few days he had downvoted nearly all of my answers or questions.  He has left comments on a number of my questions which aided in making the connection between him and the downvotes.    I know rep isn't really a big deal, but at this point this has become absolutely obnoxious.Is there no way to limit a user from downvoting another user repeatedly?  I have emailed SO, flagged his comments, flagged my own post and left a comment for the moderator (at the suggestion of the SO staff).  But nothing thus far.  I have a record breaking ~700 rep and he ~10K.    Edit:  Just to clarify, I understand that a wrong answer or less appealing answer should be downvoted.  I have no issues with this.  The downvotes I'm referring to didn't happen over days or even hours.  The majority of them occurred in the same 30 minute time span.


LaTeX can't find my .bst file. How do I show it the way?

My question is nearly identical to that posed in these:        but unfortunately, I've followed the instructions in various ways and LaTeX still doesn't find my .bst file UNLESS it is in ./ (the PWD).  I've tried 3 approaches:   export TEXINPUTS=.:~/my/path:  (attempted with both ~ and the full-path) put the file in ~/Library/texmf/  (I'm on a mac) specified the full path to the .bst file in the \bibliographystyle command   Any ideas what I'm still doing wrong?  I've tried texhash (even though it's not supposed to be necessary) and that also failed.  The fact that it works if I put the file in the same directory as the .tex file says it's not a problem with the .bst.


I am asked to solve the following problem $$\sum_{n=0}^\infty{\frac{\sin^3{(3^n)}}{3^n}}$$ My work: Using the identity $\sin{(3x)}=3\sin x-4\sin^3x$ $$\sum_{n=0}^\infty{\frac{\sin^3{(3^n)}}{3^n}}=\frac{1}{4}\sum_{n=0}^{\infty}{\frac{3\sin 3^n-\sin{3^{n+1}}}{3^n}}$$ From here I do not know how to procede, even tough it looks like it is a telescoping series, I cannot find a way to arrive at it. I also tried: $$n\rightarrow3^n\\ \sum_{n=1}^{\infty}{\frac{\sin^3{n}}{n}}\\ \text{Applying the identity}\\ \frac{1}{4}\sum_{n=1}^{\infty}{\frac{3\sin n-\sin{n}}{n}}$$ Which again looks like it might telescope, but I do not see how to arrive at the result. Any help, hint or solution is welcome!


If we want to refer to "Lemma 3.4", we can write  " Lemma \ref{number9}". Is there a command that the word "Lemma" or "Theorem" or ... appear automatic too? (i.e we write ... and in pdf appear "Lemma 3.4")  Thank you for your help.


I'm learning Factor Analysis  in SPSS. I faced the following problem. I am performing a PCA for factor extraction on a 49×5 dataset using SPSS. Separately I computed factor loadings by using the formula Loadings=(Orthonormal Eigenvectors) X  (Square root of Absolute Eigen values)  using spreadsheet (MS excel).   Two factors have been extracted in my study.  But loadings of my 1st factor in Excel  is just of opposite sign of the result of SPSS. The loadings of the second factor matches exactly in both Excel  & SPSS.  This mismatch is due the direction of orthonormal eigen vectors considered in both the cases. I can realize the fact that direction is not important but the absolute values are required to know which variables are loaded on which factor.   But  the problem arises when I am going to calculate factor scores, which will be utilized in further regression analysis. If I consider SPSS out put as right then I will get different factor scores for the first factor and if I consider Excel out put  as right then I will get a different factor scores for the first factor. Basically the factor scores in both the cases are of different sign but having same magnitude.   Which one should I accept in my research?   However , for the second factor, there is no ambiguity between SPSS result and Excel result.


How to Write a Test Class for an InvocableMethod?

I have a simple invocable method (thanks, Rakesh Gupta!) that I'm calling from a Process Builder when certain criteria are met.  I'm getting good results from the code as evidenced by reviewing data in the UI, but I'm not sure how to write a test class for an @InvocableMethod.  Here is the invocable method:  public class AssignLeadsUsingAssignmentRules  {     @InvocableMethod     public static void LeadAssign(List<Id> LeadIds)     {         Database.DMLOptions dmo = new Database.DMLOptions();         dmo.assignmentRuleHeader.useDefaultRule= true;                   Lead Leads=[select id from lead where lead.id in :LeadIds];         Leads.setOptions(dmo);         update Leads;     }  }   Here is test class that I've written:  @isTest private class AssignLeadsUsingAssignmentRulesTest {      private static testMethod void doTest() {          Test.startTest();         Lead l = new Lead(LastName = 'Test Lead',                      Company = 'Test Company',                      IsRecruitmentLead__c = True);         insert l;         Test.stopTest();      } }   The test class creates data that meets the criteria for the Process Builder, and the test class executes to completion in the Developer Console, but I'm still getting 0% code coverage for the invocable class.  Thanks in advance for your advice - Tom


I have understood that I have problem with driving High Side MOSFETs as their Gate Voltage must be bigger in respect to their Source voltage. How do I provide a higher voltage supply rail for the gate drivers than what is used for output positive voltage rail so as to turn on the MOSFETs?


How long can a can a container of unopened hummus be left out?

I have a container of Sabra hummus (garlic, for those judging my decision making abilities) that I left out for about 14 hours today. The container still has the plastic seal inside the lid unopened.  Cooked chickpeas, oil, and tahini are the main ingredients but I don't have the full ingredient list. How long could this sit out and still be good?


Existence of normal subgroups for a group of order $36$

Prove that a group of order 36 must have a normal subgroup of order 3 or 9.  Let n2 be the number of 2-Sylow subgroups of G (with |G|=36). Then n must be 1 or 3.  Let n3 be the number of 3-Sylow subgroups of G. then n3=1 or n3=4 if n3=1 we have 1 3-sylow group of order 9. and it is also a normal group(from sylow theorem ) if n2=1 there is normal group of order 4 but I cant show normal group of order 3.


Simplifying help: If ${n \choose 3} + {n+3-1 \choose 3} = (n)_3$, compute $n$.

If ${n \choose 3} + {n+3-1 \choose 3} = (n)_3$, compute $n$.  So far, I have:  $\frac{n!}{3! (n-3)!} + \frac{(n+2)!}{3! (n-1)!}$  Then I simplified to:  $\frac{1}{6} (n-2)(n-1)(n) + \frac{1}{6} (n)(n+1)(n+2)$  Is this correct, and if so, what is the next move? It needs to equal $(n)_3$.  Thanks!


Is there a best practice for blog URL formatting (dated vs. non-dated)?

Wondering whether there's any written best practice from an authoritative source (Google or a Google representative like John Mueller) that discusses best practices for blog URL formatting.  I believe I've read (although I can't exactly remember where) that including dates in your blog URL is preferred for news-based sites, while omitting the date in the URL is preferred for non-news sites.  www.example.com/2017/march/how-to-blog/ vs www.example.com/how-to-blog/  Is there any documented best practice on dated URL structures?


How can I get the first 50% of all posts (within a custom post type)?

I'm trying to make a multi column layout. Seen as CSS3 adoption of column layouts is still thin on the ground, I was thinking maybe I could grab the first half of all my posts (and then the second), and add them in their own UL elements.  I'm not sure how / if this is possible with a Wp_Query?  I want to end up with my posts in alphabetical order, but split into two lists (using two queries, I guess), thus:

a
 . . .
m

n
 . . .
z

   I could then style each list with CSS and get a layout kind of like a multi column layout in CSS3.  Does anyone have any ideas about how to structure my queries here?  edit to explain how this isn't a duplicate  It's about forming a two column layout sure, but the question is very different: 'how to get half of all posts', not how to solve a very specific layout use case as is the linked 'duplicate'. (which I didn't find on account of it not being the same question).  Further, I was looking for posts sorted alphabetically, vertically descending, not A|B, C|D as in the example.


Hotspot and Internet access together — why not?

If I try to set up a hotspot in GNOME, I get the following message:  If you have a connection to the Internet other than wireless, you can use it to share your internet connection with others. Switching on the wireless hotspot will disconnect you from <network name>. It is not possible to access the internet through your wireless while the hotspot is active.  What are the technical reasons why I can't set up an Hotspot and be connected to the Internet at the same time?


If I run CAT5/6 cables parallel to electrical cables, is it possible to shield the cables with copper tubes to stop interference?

I'm remodeling my home and I wanted to hardwire some extensions of my ethernet near my 220v outlet, by near at least a foot away from it. I was wondering, would I be able block the interference if I layer the patch extensions with copper tubes and PVC tubes to prevent EMI from the 220v line? If not, what do I do?


How to identify these HTML tags from front-end?

I have a question regarding HTML tags. I'm still not clear totally when to use <strong> instead of <b>, and <em> instead of <i>. My question is: The HTML Strong Importance Element (<strong>) indicates that its contents have strong importance, seriousness, or urgency and The HTML Bring Attention To element (<b>) is used to draw the reader's attention to the element's contents, which are not otherwise granted special importance (as per MDN). Both are used to bold out the letters. Then what's the use of <strong>, as the front-end user won't know the difference between the <b> and <strong>. Similarly, both <em> and <i> italicize the words enclosed between that tag. Then how can we identify which tag has been used? In short, I want to know when to use these tags and what are practical applications of developers using these tags. PS: I am a bit unsure about the cite tag. I understand that it's used in the titles of creative works but I'm still unclear on its usage. Please help me with this as well.


In this question:   The Accepted answer is floating along with other answers (sometimes on the 2nd level, sometimes it is the third answer), why is it treated as ordinary answers? Shouldn't it be a fixed top answer?


I tried installing gksu but getting the following error.Someone help me to fix this

sudo apt-get install gksu Reading package lists... Done Building dependency tree        Reading state information... Done E: Unable to locate package gksu


Prevent LaTeXiT from cropping large Tables


How do I compare two folders to see if they have the same files and list the common files into text file?

I have two directories which may contain the same files as the other. I want to know which files are common to both directories so that I can delete the duplicate files and save space.


Dialog Window moved to background when opening CommonFileDialog

From my MainWindow the user can open a custom dialog using the menu. This custom dialog offers the possibility to select a path using the CommonFileDialog.   The CommonFileDialog opens as it should, however, at the same time the custom dialog is moved behind the MainWindow. Now when the user exits this CommonFileDialog by either selecting or cancelling, the MainWindow is shown on top while the custom dialog is in the background.   This is really unintuive. What I want is that the windows behave like a normal stack, meaning that they spawn on top of each other and one exits them in reverse order.  Does anyone have an idea why the windows behave the way they do and how I could fix it?


Let $G$ be an abelian group of order n.   Let $\mathbb{C}^*$ be the multiplicative group of non-zero complex numbers, and suppose $f:G \rightarrow \mathbb{C}^*$ is a homomorphism. Prove that $\sum_{g \in G} f(g) = 0$ or $\sum_{g \in G} f(g) = n$.  I can prove this for cyclic groups but am unable to generalise to all abelian groups.


Create a multiboot USB drive with Ubuntu and Windows 7 using ISO images

I would like to have a bootable USB drive with some bootable ISO images on it, where some sort of menu appears on boot to select a specific image file on the USB drive and continue boot from that one.  Is there a way to create that? I am interested in e.g. Windows 7 and Ubuntu.


Direct cut-elimination for natural deduction.

Just reading:  "Gentzen was motivated by a desire to establish the consistency of number theory. He was unable to prove the main result required for the consistency result, the cut elimination theorem - the Hauptsatz - directly for Natural Deduction. For this reason he introduced his alternative system, the sequent calculus for which he proves the Hauptsatz both for classical and intuitionistic logic."   Any direct proofs of cut-elimination for natural deduction around? Whats their underlying substantial idea exactly?  Best Regards


Say I have a table of numbers 1-6. I throw a 6 sided die a number of times. Each time I get a number I have not already had, I mark it in the table. What is the expected number of times to throw the dice to fill out the table?


Does the following usage of const have any value?  void Func(const bool state) {     std::cout << "The state is: " << state << std::endl; }   const references are certainly recommended and I surely see the benefit of it. But, coming to simple const addition to non-reference parameter. Is that of any use?


How can I set the priority of Wi-Fi networks on my iOS device?

I have two Wi-Fi networks in my house, one at one end of the house and one at the other.  While signals crossing from one side of the house are usually audible on the other side, they are generally fairly weak and quite nearly unusable - something in the house's construction attenuates signals traveling through certain walls.  So, to enable good connectivity while roaming the house, I have to have my Wi-Fi clients configured for both networks.  This works fine on PCs where I can configure both networks and set a priority order, so that the system prefers the network closest to its normal location and should only roam when its usual network gets too weak.  However, I cannot find a way to set this priority in iOS.  This results in some devices occasionally connecting to the farther AP, despite being in their regular spot where they should prefer the closer one.  How can I customize the roaming preferences for Wi-Fi networks on the iOS devices?  I at least want to assign a "preferred" network for each, but would also like to know if there's a way to set a "roaming threshold" - a point at which the device should choose to change APs, versus remaining on the current one.  I'm pretty sure all my iOS devices are running iOS 5 or higher.


Solving an exponential inequality problem

How do I prove the following inequality :  $$\Bigg(\frac{2}{\alpha^2} \, \big( e^{\alpha x} - e^{\alpha y} \big) \, + \, e^{\alpha y} (y^2 - x^2) \; \Bigg) \geq 0 $$  given, $x, y \geq 0$ ?  Can anyone provide me with hints about this problem ?  Here, $\alpha$ is a strictly positive constant.


Suppose $U$ is k-dimensional vector space on complex field, and $S\in L(U)$. Assume $S$ has at least $m$  distinct nonzero eigenvalues. Show that $\def\null{\operatorname{null}} \null (S^{k-m})= \null (S^{k-m+1})$  Here is my approach:  Suppose $ S \in L(U) $ and k is non-negative integer and $S$ has at least $m$ distinct non-zero eigenvalues. If $S^{k-m} v = 0 $ for all $v \in U$, then $S^{k-m+1} v = S (S^{k-m})=S(0)=0$. Thus, $ \null (S^{k-m}) = \null (S^{k-m+1})$.  Please give me feedback on my answer. If it is wrong, direct me to right track.  Thanks in advance!


Counting the exact number of coin tosses

This is a question that has received various answers. This questions seems simple, but it proves to be rather tricky.  So :  We flip a coin (H-T) independently $10$ times. Let's for the moment not care about whether it is fair or not.   How many $3$-head sequences are there?  Solution:  Some say that the answer is $\displaystyle\frac{10!}{7!3!}$, but this is the number of ways  by which $3$ heads can be arranged in $10$ positions. This answer , however, does not say anything about the remaining $7$ positions.   Each of these seven positions can be H or T. The total number of $7$-element sequences is $1\cdot1\cdot1\cdot2^7=2^7$. Then we have to multiply this by $\displaystyle\frac{10!}{7!3!}$ as the three heads can be anywhere. But I have found that this is not the correct answer. The correct is just $\displaystyle\frac{10!}{7!3!}$. So why not multiply by $2^7$?


I'm on OSX and if I run python --version in a bash shell, I get this:  $ python --version Python 3.7.3   But the which python command appears to be pointing to version 2.7.   $ which python /usr/local/bin/python ls -al /usr/local/bin/python lrwxr-xr-x  1 me  admin  36 11 Apr 22:28 /usr/local/bin/python -> ../Cellar/python@2/2.7.16/bin/python   I think this is because I have done alias python=python3: but why does which python not pick up the alias?


Keep both accented and unaccented versions in a tsvector column?

I am facing a situation where users SHOULD submit items that are written in plain English. However, it happens that names have accents - coming from various languages. I have a tsvector column in my table which is indexed for fulltext search.  Here is the info about this column, and relevant info about the table:                                                           Table "public.companies"      Column     |          Type          |                       Modifiers                        | Storage  | Stats target | Description  ----------------+------------------------+--------------------------------------------------------+----------+--------------+-------------  id             | integer                | not null default nextval('companies_id_seq'::regclass) | plain    |              |   name           | character varying(128) | not null                                               | extended |              |   description    | text                   |                                                        | extended |              |   tsmeta         | tsvector               |                                                        | extended |              |   Indexes:     "companies_pkey" PRIMARY KEY, btree (id) CLUSTER     "companies_search_idx" gin (tsmeta) Triggers:     companies_tsmeta_update BEFORE INSERT OR UPDATE ON companies FOR EACH ROW EXECUTE PROCEDURE companies_tsmeta_trigger()   Now the problem comes when the user creates a name like français. Not all the users have the ç character at hand and those who don't will have troubles finding this entry - meaning that it will be stored with the cedilla-c in the tsvector column. So my thought was to use the unaccent extension in order to strip these accents. However now users that just type français will have problems and will not find the entry. So I came up with a function that just concatenates both versions (accented and accent-stripped) of the name and descriptions. However, descriptions can get pretty large and I worry the index will take too much storage.   create or replace function companies_tsmeta_trigger() returns trigger as $$ begin   new.tsmeta :=     setweight(to_tsvector('english', coalesce(new.name, '')), 'A') ||     setweight(to_tsvector('english', unaccent(coalesce(new.name, ''))), 'B') ||     setweight(to_tsvector('english', coalesce(new.description, '')), 'C') ||     setweight(to_tsvector('english', unaccent(coalesce(new.description, ''))), 'D');   return new; end; $$ language plpgsql;   What are your suggestions?


How to avoid loosing precision using implicit conversion (SqlParameter) with DateTime (C#) even if I am using DateTime2 in my SQL Server?

This is my definition column in my database.    I have a problem with DateTime in C# and the value that is being saved into my  database SQL Server.  When the applications sends: 2019-06-14 17:10:39.0192950  Saves into SQL Server this: 2019-06-14 17:10:39.0200000.  And When I need to check if the file already exists in my database using the following function:  protected Func<DateTime?, DateTime?, bool> TimeEquals = (x, y) =>    x.Value.Hour == y.Value.Hour       && x.Value.Minute == y.Value.Minute         && x.Value.Second == y.Value.Second && x.Value.Millisecond == y.Value.Millisecond;   That is my code when I insert the values into my SQL Server database:              foreach (var parameter in parameters)             {                command.Parameters.Add(new SqlParameter(                         parameter.Label,                         parameter.Value                     ));             }   I start having problems loosing precision. What is the best way to not loose precision when dealing with dates between C# and SQL Server?


why there are two way of using thread in java?

I know there are two ways to use a thread in java:   implement Runable extend Thread   I also know implementing  Runable is better than extending  Thread.   But why there are two ways - why not only one?  If implementing Runnable is a better approach, why is there another option?   What would be wrong with having only one option ?


Macbook Pro 13" and two external monitors

I have a Macbook pro 13" and I want to connect 2 monitors to it. Is it OK to connect one monitor via a USB-c cable directly and the other through a hub? My concern is that both the hub and the USB-c monitor will provide charging to the laptop and I'm afraid that might damage the laptop. Are my concerns valid or should it be OK?


how to make text be copied to another part of a document?

I have a paragraph in one part of the .tex file that I want to be duplicated in another part of the .tex file.  I could do ctrl-c, ctrl-v... as easy as that, but then if I modify one place, I will have to do the same for the other.  Is there a way to take a piece of text, in some part of the document, surround it by some reference marker, and then just use this reference marker elsewhere to duplicate the text?  EDIT: I could just do    \newcommand{\textA}{piece of text}   and then use "\textA" anywhere I want this text to appear.  However, I want "\textA" to be defined in a certain place in the document (in the .tex file). That location appears after the first time I want to use this macro.  Macros can be used only in places in the document after which they were defined, so I can't do that.


Is there any way to completely disable the caps lock key without using any third-party apps?  (Virtually, of course—I don't plan on jamming something under the key.)