I want check if my application is already running and close the duplicate instance.  Into my code use a semaphore based on the application file name, if already exists, halt the new instance:  program MyProgram;  uses   Vcl.Forms,   Winapi.Windows,   Vcl.Dialogs,   System.SysUtils,   System.UITypes,   WinMain in 'WinMain.pas' {WMain};  {$R *.res}  var   aSemafor: THandle;   aAppName: string; begin   aAppName := ExtractFilename(Application.ExeName);   aSemafor := CreateSemaphore(nil, 0, 1, PWideChar(aAppName));   if (aSemafor <> 0) and (GetLastError = ERROR_ALREADY_EXISTS) then   begin     CloseHandle(aSemafor);     MessageDlg(Format('Application "%s" is already running!', [aAppName]), mtError, [mbOk], 0);     Halt;   end;    Application.Initialize;   Application.MainFormOnTaskbar := True;   Application.CreateForm(TWMain, WMain);   Application.Run; end.   t works...  The question is: there is a standard/common way for make that?   i see some users use a mutex but it seem the same approch of semaphore, others iterate over the process list and check if already  exists the same process name...

How do i tell if one instance of my program is running? I thought I  could do this with a data file but it would just be messy :(  I want to do this as I only want 1 instance to ever be open at one point.


I got lots of NPEs and was wondering how you manage this common task.    There is a button in my fragment, here the WelcomeFragment. The button will clicked and the event is handled in the MainActivity class. The fragment is a NPE, the view, too ...   Here is my code snippet of my MainActivity:  @Override public void onClick(View v) {      switch (v.getId()) {         case R.id.button1:             ...             WelcomeFragment welcomeFragment = (WelcomeFragment) getFragmentManager().findFragmentByTag(WelcomeFragment.WELCOME_FRAGMENT_TAG);             if (welcomeFragment == null){                 welcomeFragment = new WelcomeFragment();             }             View view = welcomeFragment.getView();             if (view == null){                 view = new View(this);             }             TextView text1 = (TextView) view.findViewById(R.id.welcomeFragmentHeader);             text1.setText(newTextToShow + resStr);             break;   ...

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


I'm looking for a one-click shortcut to log out, restart, and boot in the opposite operating system. The only information I've found online is between Windows and Windows and I'm not sure if it's different.

I'm looking for a way to reboot into Windows from Ubuntu on a 10.10/Vista dual boot system. The specific use case is that I would like to be able to ssh into my running Ubuntu instance and issue a command that will initiate a reboot directly into Windows.  I found , but the script that it suggests isn't working:  #!/bin/bash  WINDOWS_ENTRY=`grep menuentry /boot/grub/grub.cfg  | grep --line-number Windows` MENU_NUMBER=$(( `echo $WINDOWS_ENTRY | sed -e "s/:.*//"` - 1 )) sudo grub-reboot $MENU_NUMBER sudo reboot   man grub-reboot isn't much help, but it seems to be leading me in the right direction:     set  the default boot entry for GRUB,   for the next boot only   WINDOWS_ENTRY=`grep menuentry /boot/grub/grub.cfg  | grep --line-number Windows` MENU_NUMBER=$(( `echo $WINDOWS_ENTRY | sed -e "s/:.*//"` - 1 )) echo $MENU_NUMBER   This returns the expected value, but on reboot the first menu entry is still highlighted. Any ideas why this isn't working or suggestions for other solutions?


Table dbsize loading with data of every database size every night.   dbsize (id, database_name, database_size, insert_date)    It looks like this:   - 1   dbname1   1000   1/1/1900  - 2   dbname2   2000   1/1/1900   - 3   dbname3   3000   1/1/1900   - 4   dbname1   1200   1/2/1900   - 5   dbname2   2200   1/2/1900   ... etc  I need to get result like this   - insert_date dbname1 dbname2 dbname3  - 1/1/1900      1000      2000     3000  - 1/2/1900      1200      2200   Tried with this sql, but nothing:  declare @ColumnNames NVARCHAR(MAX) = ''  declare @SQL NVARCHAR(MAX) = ''  select @ColumnNames += QUOTENAME(database_name) + ',' from  dbo.dbsize   set @ColumnNames = LEFT(@ColumnNames, LEN(@ColumnNames)-1) set @SQL =  'select * from ( select     database_name   ,insert_date    ,id     from dbo.dbsize) as BASEDATA  PIVOT   (      count(id)   for database_name   in      ('          +@ColumnNames +           ')  as PivotTable'   execute sp_executesql @SQL

My table is like this:  Sitecode    Month  Amount --------    -----  ------ XX          Jan     1000 XX          Jan     3000 XX          Apr     3000 XX          Apr     1000   What I want is, to show the result something like this:  Sitecode    MonthJAN   MonthAPR --------    --------   -------- XX          4000       4000


If I spend 20 and pay back that 20 instantly after using it, will the credit card company state that I spent 20 and paid 20 back (to the bureaus), if I paid that amount before they reported it?  Example: they report on day 20; I spend and pay back on the 19th; on day 20 they report "nothing" since, if I pay back what I owe, my credit goes back to max and my balance would be 0.  I'm just saying because having zero is bad  (check the lower part of the answer).  If having zero is bad, I would need to know at what point I should pay before the due date, but after the credit activity has taken place. I would ask the company, but there's no simple way to word this.  It would be very pointless to use the credit and pay it back instantly if they company just reports "0" to the bureaus because that is not the best thing for my credit score. Now, I'm not saying it's smart to skip payment due dates, but it seems nearly as dumb to pay too quickly if the company then says you're using no credit to the bureaus which means you never get a higher credit score despite using the credit and paying it off. The credit card company in question is Capital One.

I heard that it's good to have a balance because then the bureaus report that balance -- if you pay it off before they report it, they report zero.  Since you want the bureaus to know that you use credit because that's how your credit score increases, should I pay the balance as soon as possible or wait as long as I can before  I have searched far and wide and I am confused in what I should do here.  I want my score to increase the best and fastest way possible, but the concerns I have are not with utilization -- they are with when I should pay and how that will affect my score based on if the bureaus see any credit use or not if I may be paying too soon.  To make this very clear, I want to know if the credit utilization will still be reported if I pay my bill as soon as possible, because I want my credit use to be known -- I don't want the reported credit use to be zero if I am using credit and paying it off if before it is sent to the bureaus.  If this doesn't make sense, I'm sorry -- I can't think of any other way to word it. I want my credit use to be known to the bureaus basically, and I am worried that if I pay too soon they won't know I used any (when I did). Is there any definite, clear answer to my concerns?


I'm trying to use the First Isomorphism Theorem to show that $\mathbb{T}^1 \cong \mathbb{C}^*/\mathbb{R}_{>0}$ by constructing a surjective group homomorphism from the nonzero complex numbers to the circle group whose kernel is the set of positive reals. I haven't yet taken a course in complex variables, so I did some digging around and could only find a homomorphism from $\mathbb{R}^*$ to $\mathbb{T}^1$ defined by $f(\theta) = e^{i\theta}$. I don't really know what that means, so I'm struggling to construct any homomorphism $\phi : \mathbb{C}^* \to \mathbb{T}^1$, let alone one whose kernel is $\mathbb{R}_{>0}$.  EDIT: Does $f(z) = \frac{z}{|z|}$ work? EDIT2: Probably not. I think the image of this is actually just $\{\pm 1\}$. I really have no idea how to work with complex numbers at all.

Let $G = (\mathbb{C} - \{0\}, \cdot)$, a subgroup $U = \{x+yi \mid x^2 + y^2 = 1\}$. Use the Fundamental Theorem to show that $G/(\mathbb{R}_{> 0},\cdot)$ is isomorphic to $U$ where $\mathbb{R}_{> 0}$ denotes the positive reals.  I am struggling to find the correct mapping from $G$ to $U$ that results in the the kernel being the nonnegative reals under multiplication. I'm hoping to get help with this mapping then I can show it is a homomorphism and onto and can use the Fundamental Theorem.


For $a_0,a_1,a_2,......,a_n \in R, \,\, a_0<a_1<a_2<....<a_n$ show that $$ \frac n{a_1-a_0}+\frac {n-1}{a_2-a_1}+....+\frac 1{a_n-a_{n-1}} \ge \sum_{k=1}^n \frac {k^2}{a_k} $$ i recently studied inequalities am gm hm , tchebychev, weirstrass, cauchy schwarz. i am trying to solve some questions i don't know how to start on this one can someone please help me on this.

For $a_1, \ldots , a_n \in \mathbb{R}, a_1 < a_2 < \cdots <a_n$ and $a_i \ne 0$, show that  $\dfrac{n}{a_1 - a_0} + \dfrac{n - 1}{a_2 - a_1} + \cdots + \dfrac{1}{a_n - a_{n-1}} \ge \sum_{k=1}^n \dfrac{k^2}{a_k}$  where $a_0 = 0$.  I tried mathematical induction but not able to solve (not able to simplify n = k +1) expression.  The inequality mentioned in the chapters are   Cauchy-Schwarz Inequality  Weierstrass's Inequality  Tchebychev's Inequality  I think we need to use Tchebychev's Inequality to prove this but I'm not able to solve this.


I'm truing to upgrade my packages because Ubuntu Software Center doesn't work. It just chashes when I'm trying to execute it. In terminal I wrote:  sudo apt-get update   And here is an answer:  E: Malformed line 57 in source list /etc/apt/sources.list(dist parse) E: The list of sources could not be read.   So what should I do to solve this? And why this error occurred?

I have unistalled and reinstalled the Ubuntu Software Center as per info I found in a similar thread and I got the same response about line 91 or something like that.  I just tried to upload a screen shot but since I'm new it won't allow me to.  I also can not figure out how to cut and paste anything so I have to hand type what the error screen says, both when I attempt to open the software center and nothing happens, when I try to enter commands into the terminal to uninstall, reinstall, whatever I get the same following:  COULD NOT INTITIALIZE THE PACKAGE INFORMATION An unresolvable problem occured while initializing the package information Please report t:his bug against the 'update-manager' package and include the following error message: 'E: Malformed line 91 in source list/etc/apt/sources.list (dist parse)  E: The list of sources could not be read.,  E: The package list of status file could not be parsed or opened.   How do I report bugs?  What can be done about this.  I have searched and everything everyone says to do leads me back to the same line error message.  So, I don't know how to get to line 91 in the source list; to tell you what it says. Sorry, I'm really new to this. That is what I need is to find out how to get there and fix what it says. I would really like to NOT have to re partition my hard drive and start from scratch, so I'm really looking forward to getting this problem solved. I need to be able to install new software.


Before I start explaining I'll just get you into the code.   EditText br = (EditText) findViewById(R.id.editText);  if ( br.getText().toString() == "0") {     Toast.makeText(MainActivity.this, "It works", Toast.LENGTH_LONG).show(); }   It's that simple. But I don't understand why it doesn't work! I typed in ("1" == "1") in the if statements just to see if there is anything else wrong. But the message shows up on my phone.   The edittext field has the number 0 on it. I have no clue why this simple if statement would not work.

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


I am supposed to determine if function:  $$ f(x,y)=\begin{cases}\frac{x^{3}y}{x^{6}+y^{2}},&(x,y)\neq(0,0)\\ 0,&(x,y)=(0,0) \end{cases} $$ is continous on $\left ( 0,0 \right )$.   What I did: I substitute $y=x^{3}$:  $\lim_{\left ( x,y \right )\rightarrow \left ( 0,0 \right )}\frac{x^{3}y}{x^{6}+y^{2}}=\lim_{ x \rightarrow  0}\frac{x^{6}}{x^{6}+x^{6}}=\frac{1}{2}$  But I  do not know what to do next, I know that it is not continous, so that limit should does not exist.   Can anyone help me?

Lets study the limit   $$ \lim_{(x,y)\to(0,0)} \frac{x^3 y}{x^6 + y^2} $$  If we look at the limit along any straight line eg $y = mx$ we find that the limit tends to $0$.   Studying the limit closer we test for every curve $y = x^k$, where $k$ is some integer number.  This gives that for every $k\neq 3$, the limit tends to $0$. If  $k=3$, the limit tends to $1/2$.   Now this shows that no matter what straigt line, or curve (except $y=x^3$) the limit tends to zero. I also tried a few other polynomials and they all tend to zero.  My assumption is the following:      The limit    $$ L = \lim_{(x,y)\to(0,0)} \frac{x^3 y}{x^6 + y^2} $$   Is equal to zero if $y$ is any polynomial except $y = m x^3\,,\ x \in \mathbb{R}$.   Is the claim true? If so can anyone help proving it?


Question: An ant starts at one vertex of a solid cube with side of unity length. Calculate the distance of the shortest route the ant can take to the furthest vertex from the starting point.  Now, in the answer, the cuboid is unfolded and a rectangle of side 1 and 2 is formed. Calculating the hyptoneuse gives the distance.   That was the proposed solution. I wanted to calculate it via sqrt(1+1+1). Why is my answer wrong?

An ant is caught on one corner of a cuboid with sides $l, b,$ and $h$. It wants to reach the diagonally opposite corner, However, the ant can perform a walk only along the faces of the cuboid. What is the least amount of distance that the ant needs to walk to reach the other corner?  Example : Let $l=b=h=4$ then answer is $8.944271$. How to find it for given $l , b $ and $h$ ?


Given a set $S$ of samples from a random variable $X$ with pdf $f$ and cdf $F$, is it reasonable to estimate $F(x)$ by finding an estimation  $\hat{f}$ of $f$ via kernel density estimation on $S$, and calculating, using an appropriate numerical integration method, $\int_{-\infty}^{x}{\hat{f}(z)}dz$?  What I mean by "reasonable" is this: would there be any sort of general characteristics of $X$ (e.g., a high kurtosis of its pdf) that would ensure this estimate to be better than the one obtained via the empirical distribution of $X$ implied by $S$?

I have a set of observation, let's call it $X$ and would like to fit a cdf to it. $X$ has a distribution which is roughly approximable with the normal distribution. This CDF should correspond to a continuous distribution function.  So far I've used a parametric approach by estimating mean and standard deviation and using a normal cdf but I would like to know what other options are available and how to use them.  How does the set of available option change if I require the cdf to be a smooth curve?


I'm fairly new to Linux but not computing in general and can't find what seems to be a fairly common appearance setting.  I'd like to change the color of my mouse pointer, and perhaps its size and maybe even its shape (like a bullseye or something clever). I use dark themes when I can preserve my eyes so I was hoping for at least something a little "glowy", iridescent like a gun sight.  I just installed Ubuntu 20.04 MATE a week ago.  I've poked around on here and found an ancient post telling me to: sudo apt install dconf-editor dd@SemperFi:~$ sudo apt-get install dconf-tools Reading package lists... Done Building dependency tree        Reading state information... Done  E: Unable to locate package dconf-tools*  Must be an outdated program.  Any suggestions?

I have Ubuntu 18.04 with the gnome-desktop  and parallel the Ubuntu MATE desktop installed. While I can easily change the size of the mouse pointer (DMZ-White) in the Gnome3 desktop , this does not work on the MATE desktop. I use for this the dconf-editor.  Maybe someone knows a solution?  Thanks a lot.


Ubuntu Software has become fully transparent after switching to a Mac shell theme.

I'm using Ubuntu 20.04. Recently I've deleted some default icons from /usr/share/icons folder. I don't know if it's related, but, since then, my Ubuntu Software gets into a transparent background. There's a way to revert this?  Here is a screenshot:  Ubuntu Software


I might have moved my home folder by mistake, and now I'm stuck in a login loop. Every time I log in, the screen just flashes as if it logs in and then asks me to log in again. When pressing Ctrl+Alt+F3 and logging in it says  no directory logging in with home=/   I've looked around and it seems I've messed up the location of my home folder. But how do I fix it?

I am trying to understand system administration on Ubuntu. So, as an example, I create a dummy user using   sudo useradd -d /home/linda linda   and passwd to create the password. I check that an entry has been made using cat /etc/passwd  linda:x:1004:1004::/home/linda:/bin/sh   However, when I su - linda, I get    No directory, logging in with HOME=/    and indeed, no home directory has been created. What am I missing?  Thanks.


Let a ring $R$ and let $X\subseteq P\subset R$ such that $P$ is a prime ideal of $R$. Prove that there's a minimal prime ideal $M$ of $R$ such that $X\subseteq M\subseteq P$.  I think of using Zorn's lemma but the last one deal with a maximal subgroup and not a minimal one. Thanks.

Let $R$ be a unital commutative ring, $P$ $\subseteq$ $R$ a prime ideal, $X\subseteq P$ a subset. Show there exists a minimal (inclusion minimal) prime ideal contained in $P$ which contains $X$.   My approach: Let $\langle X\rangle$ be the ideal generated by $X$. $P^c$ is a multiplicative set, as $P$ is prime. $\langle X\rangle\subseteq P\subseteq R$ and $P^c\cap\langle X\rangle=\emptyset $ so by Zorn's lemma there exist prime ideal $I_1$ satisfying $\langle X\rangle\subseteq I_1\subseteq P$. As $I_1$ is prime, it's complement is a multiplicative subset which does not intersect $\langle X\rangle$, hence I can find prime ideal $I_2$ satisfying $\langle X\rangle\subseteq I_2 \subseteq I_1$ and so on... I've got an infinite descending chain of prime ideals and I can't be sure that the process will stop.  Hints will be appreciated, thank you.   Edit: Can I conclude that every prime ideal contains a minimal prime ideal?


Many university in North America or in Europe offer fundings for masters program . But it only for those students who have a good CGPA in undergraduate examination .I have completed my bachelor degree in Economics . I have a very poor cgpa . It's 2.84 out of 4.00. Is there any possibility that I can get myself admitted in those institution for masters program with fundings . I don't have any publication. I was champion in two Business case solving competition as extra curriculum. Will good GRE score ( like 320) help me to get fund? Can I get funding if I have a good GRE score with this poor profile?  Thank you.

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


I've installed an SSD and HDD in the optical drive slot on my notebook. I'm using windows 8.1 x64, running from my SSD which is my primary drive.  My problem is taht HDD spins up/down constantly, in the past 8 hours the number of spinups reachead 400.  I've changed "Turn off hard disk after" feature to "Never" in Advanced Power Options, but no luck, nothing changed.  Could this be a hardware oriented problem, or can I configure the energy management features for this?

I have an HPdv6t quad notebook with Windows 7 and Ubuntu 11.04 dual booted, both OSes installed on a partitioned Crucial 128 GB SSD.  I replaced my optical drive with the HDD that came with the computer which I use for most of my storage.   Same question as  but for Windows 7 - I want to keep the HDD drive spun down when I don't need it.  Occasionally it will spin down on its own but only after about 10 min of not accessing it, and then it spins back up on its own shortly afterwards for no apparent reason.  As an aside, the reason I want to do this is to prolong the life of the HDD and save battery power.  Will it even make much of a difference on either account?  How significant is power consumption of a spinning HDD compared to, say, power consumption of the screen or of the sandy bridges integrated graphics?


This is a follow-up question to        If you want to redo the same command with sudo !! after doing a command like this:  echo "something">/path/file   You can use the global replace syntax to recall the command:  !!:gs/>/|sudo tee -a /   Use a space after the -a parameter.  This is the equivalent to sudo !! but helps you bypass sudo restrictions for the < and >. Because sudo does not allow you to use [<, >].  How can I put this into an alias on my .bashrc so I can use it simple?  I tried  alias redo='!!:gs/>/|sudo tee -a /'   But this doesn't work, I get the error:  $ echo "sdfdsf">/path/file bash: /path/file: no permissions  $ redo bash: /: Is a directory tee: /: Is a directory

I'm trying to set an alias for sudo !! in Bash. I tried alias sbb='sudo !!', but it interprets that as a literal  !! and prints   sudo: !!: command not found   If I use double quotes, it substitutes the double bang in the string itself, so that doesn't work.  Is there any way to make this work? Or an alternative alias? `


I'm trying to create substrings from each index in a string using this helper method public  List<int> AllIndexesOf(string str, string value) {     if (String.IsNullOrEmpty(value))         throw new ArgumentException("the string to find may not be empty", "value");     List<int> indexes = new List<int>();     for (int index = 0; ; index += value.Length)     {         index = str.IndexOf(value, index);         if (index == -1)             return indexes;         indexes.Add(index);     } }  And the way I am using it is like this string input = "27758585926302004842"; List<int> eh = AllIndexesOf(input, "2");  So I essentially want to grab each string between the indexes in two. So the subscring between index 0 and 9 and 13 and 19. I'm just not sure how to do this without using linq

If I have an IEnumerable like:  string[] items = new string[] { "a", "b", "c", "d" };   I would like to loop thru all the pairs of consecutive items (sliding window of size 2). Which would be   ("a","b"), ("b", "c"), ("c", "d")   My solution was is this       public static IEnumerable<Pair<T, T>> Pairs(IEnumerable<T> enumerable) {         IEnumerator<T> e = enumerable.GetEnumerator(); e.MoveNext();         T current = e.Current;         while ( e.MoveNext() ) {             T next = e.Current;             yield return new Pair<T, T>(current, next);             current = next;         }     }   // used like this :  foreach (Pair<String,String> pair in IterTools<String>.Pairs(items)) {     System.Out.PrintLine("{0}, {1}", pair.First, pair.Second)  }   When I wrote this code, I wondered if there are already functions in the .NET framework that do the same thing and do it not just for pairs but for any size tuples.  IMHO there should be a nice way to do this kind of sliding window operations.  I use C# 2.0 and I can imagine that with C# 3.0 (w/ LINQ) there are more (and nicer) ways to do this, but I'm primarily interested in C# 2.0 solutions. Though, I will also appreciate C# 3.0 solutions.


Does anyone know any fun dice/card/gambling games that i can throw into my campaign for some good flavor?  Here are a few links to a  that I posted and a  of dice games.  If you've got any other good ones, please share!

Sometimes my players want to engage in gambling or other games of chance within the role-playing game itself (I know, vaguely meta). The question is two-fold:   How can I approach this without squashing their aspirations to be the next Poker King, indulge them, and not have it become an obsession or throw off game balance due to poverty and/or extreme wealth given their current place in the world? Does anybody have any good, easy/quick games that could be played in a casino/gambling-hall type locale? I'm thinking something similar to Dragon Dice, an older, briefly manufactured dice game. It should have a fantastical element but be simple enough to learn within 15-30 minutes. I'm not looking to play craps at the gaming table, but having a few alternatives should wet the party's thirst for casino-style action.   Importantly, I want to avoid a Chocobo-racing scenario (I'm referring to Final Fantasy 7 wherein players would become immersed in breeding and racing wingless birds, rather than actually spending time winning the game).


If I have a database MyDB, is it considered good practice / bad practice to use schemas other than dbo?  For example:  MyDB.reports.YearlySales MyDB.reports.TopSellers MyDB.[data].ProviderX MyDB.[data].ProviderY etc

When it comes to the dbo schema:   Is it a best practice to avoid using the dbo schema when creating database objects? Why should the dbo schema be avoided or should it? Which database user should own the dbo schema?


Let $N \subset G$ be a normal subgroup. Show there exists a finite collection of irreducible representations $\phi_i: G \rightarrow GL(V_i)$ of $G$ such that  $$ N = \bigcap{\ker(\phi_i)}$$

The question is as follows:  This can be the third part of this question :     Let $G$ be a finite group and $N$ a normal subgroup of $G$.      c) Show that $N$ is the intersection of the sets of the form $\ker \xi$ that contain $N$ with $\xi \in \operatorname{Irr}(G)$.   Some attempts:  For the finite group $G$ and $\rho$ a representation with induced character $\chi_{\rho}$, we have $\ker \rho = \{ g \in G: \chi_{\rho}(g) = \chi_{\rho}(e) \} $ by Lemma 15.17; Isaacs "Algebra: A Graduate Course". Then it makes sense to define the kernel of the character $\chi$, denoted $\ker \chi$ by $\ker \chi = \{ g \in G: \chi(g) = \chi(e) \}$.  In particular, we know that for every character $\chi$ one has that $\ker \chi \unlhd G.$ For the irreducible characters $\chi^{(\alpha)}$, $\alpha \in \hat{G}$, we give the special symbols $N^{(\alpha)}$ for $\ker \chi^{(\alpha)}$. Now what we are going to show is that knowing $N^{(\alpha)}$ for every $\alpha \in \hat{G}$ enables one to know $\ker \chi$ for every character $\chi$. Indeed, if we let $\chi$ be a character with representation as a linear combination of the irreducible characters $\chi = \sum_{\alpha \in \hat{G}} m^{(\alpha)}\chi^{(\alpha)}$, then we have  $$\ker \chi =\bigcap \{ N^{(\alpha)} :  m^{(\alpha)} > 0 \}.$$ Because if $\chi^{(\alpha)} (g) = d_{\alpha}$ for every $\alpha$ such that $m^{(\alpha)} > 0$ one sees that  $$\chi (g) = \sum_{\substack{\alpha \in \hat{G}\\ m^{(\alpha)} > 0 }} m^{(\alpha)} \chi^{(\alpha)} (g) =  \sum_{\substack{\alpha \in \hat{G}\\ m^{(\alpha)} > 0 }} m^{(\alpha)} \chi^{(\alpha)} (e) = \chi (e) $$ and so $g \in \ker \chi$.  Conversely, since one evidently has that $|\chi^{(\alpha)} (g)| \le d_{\alpha}$ for every $\alpha \in \hat{G}$ we see that for $g \in \ker \chi$ one has that  \begin{align}  |\chi (g)| &= \left| \sum_{\substack{\alpha \in \hat{G}\\ m^{(\alpha)} > 0 }} m^{(\alpha)} \chi^{(\alpha)} (g) \right|\\ &\le \sum_{\substack{\alpha \in \hat{G}\\ m^{(\alpha)} > 0 }} m^{(\alpha)} \left| \chi^{(\alpha)} (g) \right| \\& \le  \sum_{\substack{\alpha \in \hat{G}\\ m^{(\alpha)} > 0 }} m^{(\alpha)} d_{\alpha} \\ &= \chi(1)  = \chi(g)  \end{align} from where it follows from this that $\chi^{(\alpha)} (g)$ must be real and so if $\chi^{(\alpha)} (g) \le d_{\alpha}$ for any $\alpha \in \hat{G}$ then this would induce a strict inequality for $\chi(g)$  and $\chi(1)$. It follows that $\chi^{(\alpha)} (g) = d_{\alpha}$ for any $\alpha \in \hat{G}$ such that $m^{(\alpha)} >0$. Then the conclusion follows.     Can someone please let me know if I am wrong and we cannot get the result through what I wrote?   Thanks!


Please take a look at this code snippet  #include <iostream> using namespace std;  class foo{     public:     virtual void v1(){         std::cout << "In Base this:" << std::hex << this << "\n";        } };  class bar:public foo{     public:     void v1() {         std::cout << "In Derived this:" << std::hex << this << "\n";     } };  int main() {     bar a, b, c;     static_cast<foo*>(&a)->v1();     static_cast<foo*>(&b)->v1();     static_cast<foo*>(&c)->v1();     static_cast<foo>(b).v1();     static_cast<foo>(b).v1();     return 0; }   The output is  In Derived this:0x7ffe8a9e8890 In Derived this:0x7ffe8a9e88a0 In Derived this:0x7ffe8a9e88b0 In Base this:0x7ffe8a9e88c0 In Base this:0x7ffe8a9e88c0   As evident from value of this pointer static_cast<foo>(b) creates a completely new variable.   Moreover, further calls to static_cast<foo>(b) refer to the previously created variable.  Could someone explain this behavior.  EDIT: From the comments I get why static_cast<foo>(b) would create a new variable. Still what I could not understand is that why multiple calls to static_cast<foo>(b) refer to the same variable. Is is a compiler optimization ?

Someone mentioned it in the IRC as the slicing problem.


Is there an easy way in Powershell to resolve a path like c:\a\b\c\..\d   so that the result is c:\a\b\d

I have two paths:   fred\frog   and  ..\frag   I can join them together in PowerShell like this:  join-path 'fred\frog' '..\frag'   That gives me this:  fred\frog\..\frag   But I don't want that. I want a normalized path without the double dots, like this:  fred\frag   How can I get that?


Given two random variables X and Y with some distribution D, is it possible to choose a D such that Z = X - Y is uniform? Is there a standard distribution D that would satisfy this?

Is it possible to have the PDF of the difference of two iid r.v.'s look like a rectangle (instead of, say, the triangle we get if the r.v.'s are taken from the uniform distribution).  i.e. is it possible for the PDF f of j-k (for two iid r.v.'s taken from some distribution) to have f(x) = 0.5 for all -1 < x < 1?  There are no restrictions on the distribution we take j and k from except that the min is -1 and the max is 1.  After some experimentation, I'm thinking this might be impossible.


SE app version 1.4.3.7 on iOS 9.2.1.  In iOS apps in general, one is accustomed to a link being followed upon pressing and then releasing the link.  Also, the standard behavior is that, if you press (the link becomes "active") and then decide you don't want to follow the link you can move your finger up or down to scroll, which cancels the follow-link behavior when you lift your finger.  In other words, a press followed by vertical motion is interpreted as a scroll, not follow-link.  The iOS Stack Exchange app has for a long time had an annoying "feature" where if you touch an image embedded in a post and your touch gets captured as a link-activation, then the scroll-to-cancel-link behavior does not work.  Putting your finger down on an image (i.e. as part of normal scrolling in the post) captures your press and will then erroneously follow the link.  Very occasionally, you can avoid following the link by quickly flicking your finger off the left or right side of the screen, but this works less than 10% of the time.  It seems you can avoid the initial capture if your finger is already moving up or down at the instant it touches the screen, but the SE app seems to be the only one that requires this level of dexterity to avoid unwanted link-following behavior.  This does not seem to happen on regular links, only embedded images.  In previous versions following the link launched the embedded browser.  In the most recent version it now launches Google Chrome and pulls up the image in a new tab, which takes longer and is much more annoying.  Basically, the distinction between normal scrolling and following a link to an embedded image does not seem to work correctly.

When you hold your finger down on a post in the iOS mobile app, then move your finger, the page scrolls, no matter how long it is until you start moving your finger - this is fine.  When viewing posts with images in, you can tap on the image to open it up full screen for zooming etc - still fine.  When you hold your finger down on an image and begin moving it fairly soon, the page scrolls - also still fine.  When you hold your finger down on an image, but pause because you were just finishing reading a sentence, then begin scrolling, the image gets the "active" overlay and when you finish scrolling and release your finger, it opens up full screen - rather annoying and breaks the flow of reading the post.  I think the act of beginning the scroll action should cancel the "I want to open this image for full viewing" action.  iOS App, Version 1.4.0  Update: I just realised that links exhibit the expected behaviour too - holding down then pulling a link to scroll won't navigate to the link upon releasing your finger - it is just the images.    As mentioned in the comments, using the website in Safari on iOS displays the expected behaviour - holding your finger on an image makes it gain the "active" overlay, but as soon as you start scrolling it loses that overlay, and doesn't open when you release your finger.


I have 12 people that arranged in a circle and 6 balls. In how many ways can I divide them for couples to play ball that no one will be disturb by the other?  In other words:All the people arranged in circle i want to draw lines between every 2 people in the circle so that there are not cut between the diagonals.  Update: I thought more about it and the solution is exactly Catalan number of N/2, this is mean the solution of this question is Catalan number of 6= 132 options.  What is a legal arrangement is on the right, and on the left an illegal arrangement:    thank you

For $n \geq 0$ evenly distribute $2n$ points on the circumference of a circle, and label these point cyclically with the numbers $1, 2 . . . , 2n$ Let $h_n$ be the number of ways in which these $2n$ points can be paired off as $n$ chords where no two chords intersect  I want to find a recursive formula for $h_n$.  First I find $h_1,h_2,h_3$ to see the recursive nature.    $h_1 = 1$ as their only one way to make one chord  $h_2 = 2$   Now $\require{enclose}      \enclose{horizontalstrike}{h_3=4}h_3=5$ ((1,4), (2,3), (5,6) case is missed in image)  I found a wikipedia link    and it is very close to my problem, But in this link you don't need to pair off $n$ chords.  But I can't get to come up with a recursive formula for my question.  If I would to guess I would say $h_n = 2 \times h_{n-1}$, And would this means that $h_4 = 8$ ??


I am new to development of android and i don't have a fair idea how to read logcat. I am trying to develop android webview application but ran into these errors.  E/AndroidRuntime:  FATAL EXCEPTION: main E/AndroidRuntime:  Process: com.tech.neucial, PID: 25698 E/AndroidRuntime:  java.lang.RuntimeException: Unable to start activity ComponentInfo{com.tech.neucial/com.tech.neucial.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setHomeButtonEnabled(boolean)' on a null object reference E/AndroidRuntime:   at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2329) E/AndroidRuntime:   at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2391) E/AndroidRuntime:   at android.app.ActivityThread.access$900(ActivityThread.java:147) E/AndroidRuntime:   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1296) E/AndroidRuntime:   at android.os.Handler.dispatchMessage(Handler.java:102) E/AndroidRuntime:   at android.os.Looper.loop(Looper.java:135) E/AndroidRuntime:   at android.app.ActivityThread.main(ActivityThread.java:5256) E/AndroidRuntime:   at java.lang.reflect.Method.invoke(Native Method) E/AndroidRuntime:   at java.lang.reflect.Method.invoke(Method.java:372) E/AndroidRuntime:   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:898) E/AndroidRuntime:   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:693) E/AndroidRuntime:  Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setHomeButtonEnabled(boolean)' on a null object reference E/AndroidRuntime:   at com.tech.neucial.MainActivity.onCreate(MainActivity.java:39) E/AndroidRuntime:   at android.app.Activity.performCreate(Activity.java:5933) E/AndroidRuntime:   at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105) E/AndroidRuntime:   at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2282) E/AndroidRuntime:   ... 10 more   I have tried every possible way to understand but no resolve. Here is the source code.   PS: i am uploading whole source because i don't know which file has cause the issue and there have been 5 or 6 files which i can't paste here.  Thanks.

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


claims that humans are immune to Pokemon attacks.     I believe within Pokémon canon Pokémon powers are simply ineffective against humans, so trainers need no special resistance.   Yet I'm pretty sure that in the TV show, the games, and (especially) Detective Pokemon, humans have born the brunt of Pokemon attacks.  According to canon, are humans officially immune to Pokemon attacks? There may well be exceptions (say, a super-powerful Pokemon, or some other way), but has canon ever explicitly addressed this issue?   What I'm not looking for: Examples of humans being attacked by Pokemon and either taking damage or surviving. There are examples either way, but generally humans are not attacked or damaged by Pokemon, and an exception does not explain the general rule.  What I am looking for: a quote from the games, tv show, or any other canon explicitly addressing if or whether humans are immune to Pokemon attacks, or some other quote addressing why Pokemon do or do not attack humans.

Obvious comedic aspects of the cartoon show especially aside, this may be a partial explanation. Think about it:  James can breathe Weezing's smog with no ill effects. Brock was able to hug a Sharpedo. And Ash has gotten trampled, tossed, smacked, singed, smothered, submerged, routed, run over, and electrocuted so often by his Pokemon he should be perpetually hospitalized! Yet these characters always seem to bounce back without serious injury.  Considering [a] it is partially cartoon logic, and [b] Pokémon trainers, much like animal handlers, likely will get somewhat more sturdy and hardy from simply regularly dealing with the animals they train....  Is it at all possible that just being around a Pokémon somehow helps their trainers develop a higher resistance to that Pokémon's special abilities?


Based on the 2021 numbers: 401(k) elective deferrals are limited to 19,500. Limits here make sense as savings offer obvious advantages: pre-tax contributions in case of regular 401(k); non-taxed distributions in case of roth (401)k. Additionally, individuals are allowed to setup after-tax contributions. As the name suggests, these contributions are made with after-tax dollars and earnings are taxed when distributed. This is no different than any investment account. The annual IRS limit for after-tax contributions is set at 58,000 in 2021. What is the point of that limit? Why should I prefer after-tax contributions when I can open a zero-commission investment account and buy/sell the same Vanguard ETFs without limits, paying taxes on earnings?

I max out my pre-tax 401k, HSA, and do a roth IRA or backdoor Roth IRA.   With my additional savings is there any reason i would want to do a post-tax 401k instead of keeping it in a regular taxable brokerage account? Right now I have always been doing a brokerage account because I never considered the after-tax 401k.   Pros of post-tax 401k (after Tax EE deferrals)  - capital gains deferred  - dividends tax-deferred  Pros of Brokerage account.  - I can withdraw the money to invest in buy & hold real estate or other asset classes  - It can be withdrawn without penalties (but with taxes) for expenses outside of what an emergency fund would cover.   definitions per fidelity   AFTER TAX EE DEFERRALS The amount you can contribute to a retirement savings plan, using a portion of your salary that has already been included in your taxable income. Income taxes have already been calculated on the amount contributed. However, any earnings on these contributions can grow tax-deferred. Income taxes are not due on any earnings until they are withdrawn from the plan.  Your company may match all or a portion of your after-tax contributions in order to provide them with the most flexibility regarding taxes. (It may be advantageous for some people to pay taxes on the contributions now, because they would be in a higher tax bracket during retirement).


I have a method that is supposed to return a ByteBuffer. The meat of the method does the following:  if (true) {     //code that puts some data into ByteBuffer bb     return bb } else {     //should not be writing any data to bb      //intention: leave bb as is     return null; }   After calling this method and putting the necessary data into the ByteBuffer, I turn it into a byte array by first calling bb.flip(). However, if the last iteration through the if-else loop happened to be false, the last data inputted was null and I get the java.lang.NullPointerException error.     According to the page above, I'm supposed to return a zero-length ByteBuffer, but I'm not sure how to return something like that.  Any ideas on how to return an empty byte buffer?


I am using ANT Build too to migrate the Custom Object Named as      All Component Failures:   1.  objects/TxConfiguration__c.object (TxConfiguration__c.W_Page__c) -- Error: duplicate value found:  duplicates value on record with id:  (line 3, column 13)   Here is the field which I am trying to migrate...  <?xml version="1.0" encoding="UTF-8"?> <CustomObject xmlns="http://soap.sforce.com/2006/04/metadata">     <fields>         <fullName>W_Page__c</fullName>         <deleteConstraint>SetNull</deleteConstraint>         <externalId>false</externalId>         <label>Wizard Page</label>         <lookupFilter>             <active>false</active>             <filterItems>                 <field>TxConfiguration__c.RecordTypeId</field>                 <operation>equals</operation>                 <value>W Page</value>             </filterItems>             <isOptional>false</isOptional>         </lookupFilter>         <referenceTo>TxConfiguration__c</referenceTo>         <relationshipLabel>Wizard Page</relationshipLabel>         <relationshipName>W_Page</relationshipName>         <required>false</required>         <trackHistory>true</trackHistory>         <trackTrending>false</trackTrending>         <type>Lookup</type>     </fields> </CustomObject>

When I try to redeploy an object that exists in source and destination orgs, the deploy fails with the cryptic and useless error message:  duplicate value found <unknown> duplicates value on record with id: <unknown>   This fails whether I deploy with Migration Tool or IDE. Note, individual fields are deployable, but not the object.


So tensors come up a lot in machine learning in various settings. Any math major will have studied linear algebra heavily and it's usually much simpler to use linear operators and the corresponding notation when working with matrices. I assume that similar notation exists for tensors and that using it would bring the same benefits of simpler to memorize formulas and less clutter when doing computations. Are there any good books or other sources that covers this topic?  I'm interested in a theoretical treatment, i.e. the definition, theorem, proof style with the assumption that the reader can handle abstract math.

I've noticed lately that a lot of people are developing tensor equivalents of many methods (tensor factorization, tensor kernels, tensors for topic modeling, etc) I'm wondering, why is the world suddenly fascinated with tensors? Are there recent papers/ standard results that are particularly surprising, that brought about this? Is it computationally a lot cheaper than previously suspected?  I'm not being glib, I sincerely am interested, and if there are any pointers to papers about this, I'd love to read them.


I have created a backup of a SQL database in SQL 2014 and want to use this backup to restore it to a different machine that also runs SQL 2014, hence no version issues. However, I keep receiving an error that the system cannot find the .mdf file. Once I have selected the backup file I receive the  check mark that the database is ready to be restored but as soon as I click Ok the error appears. Error message below; the provided link to MSFT does not contain any information.     TITLE: Microsoft SQL Server Management Studio Restore of database   'BEWEBAPP' failed.   (Microsoft.SqlServer.Management.RelationalEngineTasks) ADDITIONAL   INFORMATION: System.Data.SqlClient.SqlError: Directory lookup for the   file "C:\Program Files\Microsoft SQL   Server\MSSQL12.SQLEXPRESS\MSSQL\DATA\BEWEBAPP.mdf" failed with the   operating system error 3(The system cannot find the path specified.).   (Microsoft.SqlServer.SmoExtended) For help, click:      Does this means that a backup can only be restored to the machine it was taken from?? Frankly, I do not understand why restoring a database has to be so difficult.  Any solution for this problem are well appreciated.

I Copied some database backups from one server to another server(new instance no databases are present).I tried restoring using below command   Restore database dbname from disk='g:\e2bak\dbname.bak' with  stats=10   It failed with below error     Directory lookup for the file "G:\MSSQL$s73g\MDF\dbname.mdf" failed   with the operating system error 3(The system cannot find the path   specified.)Msg 3156, Level 16, State 3, Line 1   Also server level default database settings are to store data and log in   G:\MSSQL10_50.SG\MSSQL   I can overcome the error by specfying move option. But my confusion here is  1.Why database .bak file is looking for G:\MSSQL$s73g\MDF\dbname.mdf",this is the path   of dbname database files in production from where we copied the .bak file  2.Also when I restored the database with move option and took a backup in same server,   I was able to restore the Database with below command  Restore database dbname  from disk='G:\e1ebk\dbname.bak' with replace,stats=10   Can you please help me understand why .Bak file location is pointing out to some other directory(which doesn't even exist in our server and existed only on production server) and in second case why this worked without move option.


I wan't to install wine in Ubuntu but  after type this sentence a message appear that says :   E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied) E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?   what is the solution of this problem?

I get this error when trying to use apt-get:  E: Could not get lock /var/lib/dpkg/lock - open (11 Resource temporarily unavailable) E: Unable to lock the administration directory (/var/lib/dpkg/) is another process using it?     How can I fix this?


I am insertnig into a table using a selection  INSERT california_authors (au_id, au_lname, au_fname) SELECT au_id, au_lname, au_fname FROM authors WHERE State = 'CA'   say i have an identity column in california_authors. Can i get all the ids inserted by the above particular insertion just like i can get @@IDENTITY for last single insertion ?  I can't use select command for california_authors as there may exists previously inserted records with filter State = 'CA'

I'm inserting multiple records into a table A from another table B. Is there a way to get the identity value of table A record and update table b record with out doing a cursor?  Create Table A (id int identity, Fname nvarchar(50), Lname nvarchar(50))  Create Table B (Fname nvarchar(50), Lname nvarchar(50), NewId int)  Insert into A(fname, lname) SELECT fname, lname FROM B   I'm using MS SQL Server 2005.


I need to create a searchable material dropdown that excludes grease pencil materials. However if I do it like this row.prop_search(item, "material_selector", bpy.data, "materials")  then all the materials in scene get included in material dropdown. How can I give custom search elements to prop_search method instead of generic bpy.data?

Is it possible to somehow search all objects on the scene which have a custom property enabled using prop_search?  I know how to do this with dynamic EnumProperty but it seems to be not an option as it has some bugs.


I'm working on a simple registration form which, when invalid data is entered, will display both a generic error (e.g: "There is an error on your form") and also specific errors (e.g: "This is not a real email address").  The specific errors will be placed next to the relevant input field, but I'm wondering where best to put the generic message, at the top of the form or at the bottom next to the submit button.  My thinking for placing it at the top is as follows...   Broad content (generic message) will drill down to specific content (messages). Screen readers will be told right at the start of the form that there's been a problem, rather than having to go through the whole form again (if it's at the bottom, they won't know there's an error message there until they get to it) Having a generic message at the bottom seems a bit pointless if the user has already gone back through the form and acted on the specific messages (especially relevant for screen readers) If the page increases in size (likely as more fields may be added), submitting the form would trigger a page reload, causing the generic message to drop below the fold.   On the other hand, placing it at the bottom would...   Maintain the practice of having the error in close proximity to the relevant input (in this case, the submit). Potentially be easier for visual users to orientate themselves, as the last thing they would be fixated on would have been the submit, so placing the message next to it would require less scanning on their part.

I've seen quite a lot of research on form design, but so far, I haven't come across any studies on error message design best practices. The only piece of advice seems to be that each error should clearly be associated with the invalid form field that it aims to correct. Has there been any research on this?  I have some specific issues I'm trying to work through and would appreciate any insight or resources.  Error message location  When you have live form validation, where should an error (or success) message appear in relation to the form element?  Some options:    To the right of the input         – Wireframes created with     To the right of the label            Above the label            Below the label            Below the input            There are some thorny issues that also need to be taken into account regarding location:   How are errors displayed for radio or checkbox groups? How wide is the error message? Is the error message multi-line?   Error message visibility  Besides location, I'm also interested in how the visibility of the error message affects its usability. Does it matter or is it strictly a aesthetic decision?  Consider the following 3 options:          Edit: There have been some excellent points on accessibility in some of the answers so far, as well as some interesting examples. However, I really would like to see some data from actual studies, if possible. Also, none of the answers so far have really addressed the two questions I had above:   Where should the error be located in relation to the input and label? How does the design and visibility of the error message itself affect its usability?   Regarding the accessibility of the forms, it seems to me as if there might be two potentially conflicting use cases, live validation and server-side validation (which would require reloading the page). If the page is reloaded and the user again starts at the top of the form, an error summary makes sense, especially from an accessibility perspective. However, in the case of live validation, the error summary at the top makes much less sense, both for form design and for accessibility purposes.   Consider how a user would actually use a form with live validation:  The validation occurs on the blur event. Usually, the focus of will be on the next form element, not the list at the top. As I understand screen readers, there wouldn't be any reason to return to the top of the form to read the error list. For users not using screen readers, the error list at the top pushes the entire form down, doubly so if the error takes up vertical space near the form field as well. In longer forms, this is a usability issue as the error summary may not be visible. In shorter forms that have per-field errors, like a login, the error summary just looks like overkill. For all forms, the interface would be pushed down, making a poor user experience.  For live validation, if you really want to make the form errors accessible, I think using  might be the preferred solution.


I want to install flash player on ubuntu 16.04 LTS. how i perform it kindly concern with your best

Even though I have the latest Adobe Flash player 11.2 for Linux in Firefox -   - a particular online flash game still requests that I update to the latest flash player.  I've tried this online game on my laptop (Windows 8 with Flash Player 11.8) and it has no problems.  Is there a way to trick Ubuntu or this game into thinking Flash Player 11.8 is "installed"?


Prove that if G is a group and H a subgroup of index n, then G has a normal subgroup K with [G : K] ≤ n!  I'm having trouble proving this because frankly I have no idea where to start. Any tips?

I would be very thankful if someone could give me a hint with proving this. It's a very common exercise in abstract algebra textbooks.     If $G$ is a group with a subgroup $H$ of finite index $n$, then $G$ has a normal subgroup $K$ contained in $H$ whose index in $G$ is finite and divides $n!$.   I found the proof on  at some point (although the proof appears to be no longer there), but I got lost in one of the details.


I wanted to simply create a cylinder with height of 1cm and a radius of 10cm. So I set the corresponding scales in the toolbar:   After that I went into edit mode, I enabled the edge length overlay and selected an edge from the bottom to the top:  I expected that it would be 1cm long (which is what I typed in object mode), but it is 20 cm. I also noticed the "Scale" entries in the toolbar in object mode. If you multiply 20cm by 0.005 you would arrive at 0.1cm which does not make any sense. What's going on? Is this a bug? I tried this in version 2.83.15 and 2.93.0 same behavior.

I just found out about the Mesh Display : Length feature in the "N" panel (thanks to ) that allows one to measure the length of a face or vertice.  But my first encounter with this tool gives me complex feelings of love and hate, see how, as I was trying to measure the aspect ratio of this TV screen, I am getting WIDTH = 20.33 and HEIGHT = 37.57.  These values seem awfully wrong, since my betrusted eyes tell me the height should be shorter than the width.    I have tried measuring the single vertices as well, to identical results.


I have notice two issues with the reputation graph: 1: This user has a higher score on the graph than in reality I happened to notice  where the user's graph reputation does not match their actual reputation.  The person in question was hit by a -100 penalty for an offensive answer a while back, but the graph doesn't reflect that.  I thought it just didn't update when I noticed this at the time, but the person has since gained and lost reputation and at all times the graph was +100 of their actual reputation.  It seems, based on Shadow Wizard's comment that this is because the reputation change is non-public. OK, fair enough... , which was marked as , noticed a similar phenomenon for placed DVs.  This prompted me to examine graphs more carefully.  It seems that this hidden -1 has been updated, as I checked several users and did not find any others that had lower actual reputation than graph reputation, so .  (Since the number of DVs placed is public, I can be reasonable sure that these users have placed -1 rep DVs, although strictly speaking they could be 100% question DVs.) 2: Some users have a lower score on the graph than in reality I did, however, find many users where the graph says their reputation is much lower than it actually is.  Perhaps that is from deleted downvotes turning into hidden +1s, but those should be balanced by hidden -1s, so its not clear what happened.  Seems there is some error in the logic - maybe the -1s do affect the graph now as per the , but the corresponding +1s don't?  Whatever the case, I can't imagine it is intentional. Edit: I went back to find some examples today & didn't find any.  I think the issue has been resolved - either it was a caching issue or a change was made to the code after this post.

If a post is deleted as spam or offensive, the user incurs a 100-rep penalty.  But SE made the conscious decision to not call that out on the reputation tab; if you go to the page of a user who's hit this penalty, you won't see those "-100" events in the history.  The big rep number on the profile will be correct (which is important for knowing about privileges), so you'd only notice the difference if you went through the history and added everything up -- probably not something that happens often. So these rep penalties would be invisible to most viewers, but for one thing:  (You'll need to get your own test case to verify this behavior; I'm not going to call out specific users.) How is the current rep both 404 and a smidge over 500 at the same time?  There's only one way I know for that to happen (and I know it happened here). You might think that, theoretically, answers that the user downvoted could account for the difference, because those too are not shown in rep history. But the -1 rep for downvoting answers is reflected in the graph, even if an audit of the rep history would come up with a different number. Additionally, reputation changes from normal deleted posts don't cause a discrepancy between the graph's reputation and actual reputation either. If we don't want to call out these events in the rep history, should we also do something about this graph to avoid broadcasting what happened in the summary?


Im much confused with the node editor. I want to know are there any ready made material with addon or website directly i can just apply (gold, silver, cloths, metallic etc) with material and textures

I'm wondering if there's any addons or online libraries of materials I can download. I've found one called , but then discovered it was from 2008 and thought by now something like that might already be integrated into Blender.


Is it possible to get and store a specific y value from a plot coordinate, so that it can be printed somewhere else (for example inside a node)? \documentclass{standalone} \usepackage{pgfplots} \pgfplotsset{compat=1.17} \usepgfplotslibrary{fillbetween} \begin{filecontents}{data-fake5.dat} x       y   1       0   2       3   3       1   \end{filecontents} \begin{document} \begin{tikzpicture}    \begin{axis}[ axis x line*=bottom, axis y line*=left,  ] \addplot[name path=myplot] table[x=x,y=y] {data-fake5.dat};  %\node at (1,1.5){\printy{myplot}{2}}; %this should print the y value of the plot 'myplot` associated with x=2, which is 3 \end{axis}   \end{tikzpicture}  \end{document}   desired result:

I am unable to get the right coordinate values for (A) and (B) in the following axis. Did I misunderstand some conversion step or is it because of the data?  Picture    MWE  \documentclass[ a4paper ]{scrartcl}  \usepackage{     newtxtext,     amsmath,     tikz,     pgfplots } \usepackage[T1]{fontenc} \usepackage[utf8]{inputenc}  \usetikzlibrary{     calc }  \listfiles  \begin{document}  \begin{center}     \begin{tikzpicture}[font=\small]     \begin{axis}[     height=6cm,     width=14cm,     %     scale only axis=true,     xlabel={Distance in mm},     ylabel={Voltage in volt},     ]     \addplot [sharp plot, no marks, x=Wegnormiert] table [col sep=tab] {data.txt} coordinate [pos=0.5] (A) coordinate [pos=0.6] (B);     \draw (A) -| (B);     \filldraw let \p1= (A) in (\x1,\y1) circle [radius=1pt] node[pin={[pin distance=1.1cm]270:{{\pgfmathparse{\x1}\pgfmathprintnumber[fixed,precision=2]{\pgfmathresult}\,pt}}}] {};     \filldraw let \p2= (B) in (\x2,\y2) circle (1pt) node[yshift=-0.5cm, pin=270:{{\pgfmathparse{\x2/2.845274}\pgfmathprintnumber[fixed,precision=2]{\pgfmathresult}\,mm}}] {};     \end{axis}     \end{tikzpicture} \end{center}  \end{document}   Data    Additional  code for y-coordinate  \documentclass[ a4paper ]{scrartcl}  \usepackage{     newtxtext,     amsmath,     subcaption,     biblatex } \usepackage[T1]{fontenc} \usepackage[utf8]{inputenc}  \usepackage{     tikz,     pgfplots     } \usetikzlibrary{     calc }  \listfiles  \begin{document}  \begin{center}     \centering     \begin{tikzpicture}[font=\small]     \begin{axis}[     height=6cm,     width=14cm,     %     scale only axis=true,      xlabel={Distance in mm},      ylabel={Voltage in volt},     ]     \addplot [sharp plot, no marks, x=Wegnormiert] table [col sep=tab] {data.txt} coordinate [pos=0.5] (A) coordinate [pos=0.6] (B);     \draw (A) -| (B); %   \filldraw let \p1= (A) in (\x1,\y1) circle [radius=1pt] node[pin={[pin distance=1.1cm]270:{{\pgfmathparse{\x1}\pgfmathprintnumber[fixed,precision=2]{\pgfmathresult}\,pt}}}] {};     \filldraw let \p2= (B) in (\x2,\y2) circle (1pt) node[yshift=-0.5cm, pin=270:{{\pgfplotsconvertunittocoordinate{x}{\x2}\pgfmathprintnumber[fixed,precision=1]{\pgfmathresult}}}] {} node[yshift=0.5cm, pin={355:{{\pgfplotsconvertunittocoordinate{y}{\y2}\pgfmathprintnumber[fixed,precision=1]{\pgfmathresult}}}}] {};     \end{axis}     \end{tikzpicture} \end{center}  \end{document}


I came across the below image today and thought it a great idea for storing bikes. However I wasn't sure if literally hanging a bike by its front wheel might cause undue stress to either the wheel itself or the front forks. Has anyone else done this to no ill effect? In the image below the back wheels don't even seem to be touching the floor, which I would have thought would take some of the weight.

Does it not distort the wheel to have the weight of the bike hanging from just that one spot?   Is it OK for any kind of wheel?  I have nicer race-type wheels on mine.  [Edited to connect with  ]


Prove that if G is isomorphic to K and H is isomorphic to K then G and H are isomorphic to each other. My strategy thus far has been to show that we can use composition of the respective isomorphisms to map from G to K then K to H. Would it be conclusive to show that this process can be inverted thus proving G and H are isomorphic?

An isomorphism is simply a bijective homomorphism. How would one show that isomorphism's are symmetric, reflexive, and transitive?


Conversely, is it true that if every sequence of pointwise equicontinuous functions from $M$ to $\mathbb{R}$ is uniformly equicontinuous, them $M$ is compact?

If every sequence of pointwise equicontinuous functions $M \rightarrow \mathbb{R}$ is uniformly equicontinuous, does this imply that $M$ is compact?


I want to send mail in every 7 days i.e please login site, you are not logged in since 7 days, only for those users which are not logged in since 7 days. I have already created an event i.e After creating new user a/c. But I don't think so that this event is good for existing users.  What event I need to add? What condition am I apply to check [account:last-login]<7 days & send mail in every 7 days.  Please Help. Thanks

I am using Drupal 7, and I want to send email to registered users who have not logged in to the site since 30 days; for example, an email saying:     Hello user, you are not login since 30 days.   Is there any way?


Today I visited the  to find  who got selected as the moderators. But in the results of the year 2018, I found something strange. It displays the username Snow.  has been a member in The Workplace only for 4 months.  I suspect there was an old user with the same username and their account got deleted as it leads to a  page.  Can this be fixed?

On Philosophy, one of the elected moderators has since deleted their account, and they're shown as "Departed" on :        However, , one of the elected moderators still has their "previous" flair shown in place, despite the fact that they've already resigned and left the Network completely in the wake of the recent events.        , the same happens (old flair remains), but without the clickable <a> around the image, and with a noticeable :        This looks inconsistent, so when exactly will a placeholder image showing "Departed" replace the flair for a departed election winner?


I've created the following MWE: \documentclass[aspectratio=169]{beamer}   \usepackage[citestyle=authoryear-comp,bibstyle=authortitle]{biblatex}  \begin{document}    \begin{frame} \begin{itemize} \item This is a bullet point \item Here, this is a very very very very very very very very very very extremely long bullet point that basically never ends, because it continues on the second line \end{itemize} \end{frame}      \end{document}  The second bullet point is so long that it gets continued on the next line, but with less indentation than usual (see picture below). If I remove any one of the options to the biblatex package, the indentation works as it's supposed to work. It doesn't matter if there are any actual citations in the document.  Any idea how to fix this? PS: I'm doing this with MacTeX 2020, and after having updated all packages to their current state, today. PS2:  indeed solves it.

I have this problem where it seems that itemize starts with a blank space, whereas the next line starts without it. Is there a way to have both the first and second line aligned? I am using LyX.  This is a minimal code with the behaviour: \documentclass{beamer} \usepackage[bibstyle=authoryear]{biblatex} \begin{document}  \begin{frame}{Test}  \begin{itemize}  \item Test Test Test asdjakhsdahsdk aklsdjklajsd akljsakljd tehlasdklhasd asdhkadha asdhasdha asdhashdasd   \end{itemize}  \end{frame}  \end{document}


i've looked around for it but I cant find it. Is it in the main menu or a specific location in the game? Thank you.

Where are the slaughter arenas in the game and which one can I get to the earliest? I just finished the part where Sanctuary lifts off.


this is my first time using linux ubuntu.  I'm trying to install java, i downloaded the file from the java website, extracted the file to the desktop and the extracted file's name now is jre1.7.0_45  i'm following this to install the java   but omg i can't even get past number 2. i get  Reading package lists... Done Building dependency tree E: Unable to locate package openjdk-7-jre   how can i do this please?

How do I install Java, including in my browser, so websites with Java work?


I know that we can write \sin x to get a non-italic sin. I would have expected there to be a similar command for curl, so I could write \curl \mathbf{F}. Is there such a command, or should I define my own?  Also, this really seems like a question for Google/a manual, but after making quite a few searches all I could find was information on how to format \nabla \times \mathbf{F}. Am I looking wrong or is this just something no one is interested in?

Mathematical operators, such as function names, should be set in roman type, not italics. Latex already has commands for some operators, including \max, \min, and \log.  How can I define additional such commands?


How can we prove that all irrational numbers in real line can not be represented as union of countable closed sets.  The result intuitively makes sense and we all know the irrational numbers are uncountable and dense on $R$. And I don't know how to use these facts to prove the result in strict math language.

I want to proove that the set of irrational numbers is not a $F_{\sigma }$ set and also the set of rational numbers is not a $G_{\delta}$ set using Baire theorem.  I started with saying that $\mathbb{R}$\ $\mathbb{Q}$ is a $G_{\delta}$ set because $\mathbb{R}$\ $\mathbb{Q}$ = $\bigcap_{ q\in\mathbb{Q}}^{}$$\mathbb{R}$\ {q}.   So, if $\mathbb{R}$\ $\mathbb{Q}$ were also $F_{\sigma }$ then $\mathbb{Q}$, as a complementary, would be a $G_{\delta }$ set.   Both $\mathbb{R}$\ $\mathbb{Q}$ and $\mathbb{Q}$ are dense in $\mathbb{R}$ and ($\mathbb{R}$\ $\mathbb{Q}$) $\cup $ $\mathbb{Q}$ = $\mathbb{R}$, so the whole space can be written as a sum of two dense and $G_{\delta }$ sets.   I've read that this is a contradiction with Baire theorem, but I can't see this.


I had three drives on my computer: C: D: E:  I installed Ubuntu 12.04 on the E: partition and now I'm using Grub boot manager to boot into Windows 7 and Ubuntu  I'm planning to install Windows 8 by removing Windows 7 on C:, but I don't want my old Ubuntu Installation to suffer.  Is there are way that after Windows 8 removes Grub from C: that I'm able to boot to Ubuntu again.

I installed Windows 7, which ate Ubuntu's boot file. When starting up the computer, it now goes straight to Windows, without giving me the option of booting Ubuntu.   How can I get Ubuntu back?


I found an IMHO annoying behavior of the App: it does not save which question sort I'm using.  I normally use the "Newest" sort, but "Active" is always selected. As the default sort, I think it is okay, but it also changes back to the default when I look at a question and press the Back button.  It would be really useful if the app can remember the sort I'm using.

Opening the menu and selecting an item from the "Favorite Sites" menu allows us to see a feed for a specific site. In the top right corner of this page is a drop-down which allows us to select the "sort order" for the posts. The default is "Active" with other options like "Newest", "Hot", etc.  The problem is that when I select "Newest" or any other option. This preference is not remembered when I change between a different "Favorite Site".  So I am requesting that the selection is persisted when changing between site feeds. I have no preference whether this is implemented per site (to allow a different default for each site) or just one single preferred default that works on all sites (last option selected). I just want it to remember that I have selected "Newest" when I am flicking though the sites.


I have $$ L = \{A \in \mathcal P(\mathbb N) | A \text{ co finite over } \mathbb N\}$$  How can I prove that $L$ is countable?  Thanks

Show that the set of all finite subsets of $\mathbb{N}$ is countable.   I'm not sure how to do this problem. I keep trying to think of an explicit formula for 1-1 correspondence like adding all the elements in each subset and sending that sum to itself in the natural numbers, but that wouldn't be 1-1 because, for example, the set {1,2,3} would send to 6 and so would the set {2,4}.  Multiplying all the elements in each subset and sending that product to itself in the natural numbers wouldn't work either since, for example, {2,3} would send to 5 and so would the set {1,5}. Any ideas?


How do I integrate the trigonometric term ?  $$\sec^{3} \theta$$  My assumption  I tried to write it in cosine form and apply formula of $\cos^{3}\theta$ , but to no purpose. What should I do ?

I need to calculate the following indefinite integral:  $$I=\int \frac{1}{\cos^3(x)}dx$$  I know what the result is (from Mathematica):  $$I=\tanh^{-1}(\tan(x/2))+(1/2)\sec(x)\tan(x)$$  but I don't know how to integrate it myself. I have been trying some substitutions to no avail.   Equivalently, I need to know how to compute:  $$I=\int \sqrt{1+z^2}dz$$  which follows after making the change of variables $z=\tan x$.


Let $Y$ be a random variable s.t. $E|Y|<\infty$. Let $E[Y|\mathcal{G}]$ and $Y$ have the same distribution. I need to prove that $E[Y|\mathcal{G}]=Y$ a.s. How does one use the fact that a random variable and its conditional expectation has the same distribution ?

Let $X$ be in $\mathfrak{L}^1(\Omega,\mathfrak{F},P)$ and $\mathfrak{G}\subset \mathfrak{F}$.  Prove that if $X$ and $E(X|\mathfrak{G})$ have same distribution, then they are equal almost surely.  I know what I have to show, that $X$ is $\mathfrak{G}$ measurable, but I don't know how...


Given that the real numbers $a,b$ satisfy $a^3 + b^3 +3ab = 1$, find $a+b$.   I tried to factorize it but unable to do it.

Solve the following equation for $(a,b)\in \Bbb{Z}^2$:   $$a^3+b^3+3ab=1$$   I tried all of the standard techniques I know. I tried modular arithmetic:  $$a^3+b^3+3ab\equiv 1 \pmod{3} $$ $$a^3+b^3\equiv 1 \pmod{3} $$  Now by Fermat's Little Theorem:  $$a^2 a+b^2 b\equiv 1 \pmod{3} $$ $$a+b\equiv 1 \pmod{3} $$  But I can't see the next move I have to do. I can't find any banal factorization of the first term(it would require solving a $3$ degree equation). I tried using classic scomposition such as the sum of $2$ cubes and the cube of a binomial. Thank you for your time :)


//given array in main class   class Program      {          static void Main(string[] args)         {             int[] nums = new int[] { 1, 5, 7, 10, 20, 12};             BinaryTree bt = new BinaryTree();                          //what I want to do             bt.insertElement(45);          }     }  // don't mind that the class says binarytree I just want to know how to insert a number in an array  public class BinaryTree  {         public void insertElement(int num)      {          //not sure how to go about it       }  }

How to add new item in existing string array in C#.net?  I need to preserve the existing data.


I have a script, with two jQuery click functions in. The first one works perfectly, but the second doesn't work at all. Even though they follow similar code pretty much, just with different selectors. Anyone got any ideas? Thanks in advance! <script type="text/javascript"> jQuery('li.inactive').click(function() {     var letter = jQuery(this).attr("id");     jQuery('li.active').addClass('inactive');     jQuery('li.active').removeClass('active');     jQuery(this).removeClass('inactive');     jQuery(this).addClass('active');     jQuery('div.profile-mini').hide();     jQuery("div#" + letter).show(); }); jQuery('li.active').click(function() {     jQuery(this).removeClass('active');     jQuery(this).addClass('inactive');     jQuery('div.profile-mini').show(); });

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


I want the name of command running , e.g unzip to be visible through the title bar of gnome-terminal , but it seems to be impossible , if the application running doesn't set a title explicitly , even though I choose 'Replace initial title' option in the profile dialog.

I often run commands in parallel that take a long time to finish and sometimes I lose track of what is running where since they output basically the same sort of information on screen.   Do you know of any way to find out what command is running in what terminal?


We know that there is a particular velocity with which a satellite will move in a circular orbit ( orbital velocity ) but if its velocity is more than the orbital velocity but less than the escape velocity then it would move in a elliptical orbit, however  but my question is that why it moves in a elliptical orbit when it is moving with velocity more than the orbital velocity?  Further this question can be extended because it indirectly also asks that why is there a specific value of escape velocity and also why the escape velocity is $\sqrt2$ times the orbital velocity?    thanks in advance!

Almost all of the orbits of planets and other celestial bodies are elliptical, not circular.   Is this due to  by other nearby massive bodies?  If this was the case a two body system should always have a circular orbit.  Is that true?


I do a lot of video converting on my laptop, and I notice that during conversion the temperature of the processor is between 90C-99C, which is a bit alarming for me.   I am using Windows 8.1 and I can't find any option in task manager to limit computational resources. My current fix for this is to disable hyper-threading and turbo-boost in BIOS setup which helps to limit CPU temperature around 80C, but it also reduces overall speed of my computer.   Is there another way of doing this within Windows for a single process?

I am using an old laptop and doing heavy processing that needs high CPU usage for a long time (~30mins - 2hours). When the process puts heavy load on CPU for a long time, CPU overheats and computer shuts down. I don't want to use a cooler/stand because I am carrying this laptop around and working outside home.  Is there a way/application that I can limit CPU usage of a process in Windows?  Note: Setting the priority of the process from task manager does not work.  Note 2: Fans are clean.


My last visit to the US was on Dec 17-2014 until Mar 14-2015 under the ESTA/VWP. I flew home in the Netherland after that. I plan to fly to Mexico on 15 May and want to stay there for a month, then get back to the US by motorcycle on 15 June. Would it be alright with the 90 days rule ?

I am a British citizen visiting the USA in early August for a two week vacation with friends. After the holiday I'm returning to my home in the UK for three weeks. After that I will return to the USA and will be working for my British employer under the Visa Waiver Program for a period of 80-85 days.  I have read already that there is technically no problems with this under ESTA rules, but should I limit this working period to a shorter time frame (e.g. 70 or so days) so that it does not negatively affect the decision made by the POE officer? Ideally I would love to be over in the states for the near-full 85 day period.  Any advice or previous experiences anyone can offer?  Some clarifications: As confirmed by the immigration attorney, as I am employed by my UK employer, it will be regarded as a business trip, the important part being that I will be working officially as a consultant for my UK employer just overseas for the allotted 85 or so days


Here on Meta, I was able to edit , without it going to a review queue, even though I only have 268 rep here.  However, on Spanish SE Beta, I have 800 rep and my edits go to the review queue.  What's the difference?

Some questions and answers are marked Community Wiki and are owned by a community wiki user:  (In fact, this very question is one of them)  Why have Community Wiki posts? How do Community Wiki posts work? How does a post become a Community Wiki post? How can the Community Wiki status be removed from a post? How can I find Community Wiki posts?


I have a custom post type for events, and I wish to remove the Publish/Visibility options from the side as they are not relevant to the user.  Is there a way to do so?

I have a custom post type (called contacts). Since this post type is not working like a post, I don't want to show SAVE DRAFT, PREVIEW, Status, Visibility or Publish Date.  The only options I want to show are PUBLISH & Move to Trash buttons.   Is there a way to hide these other options? If not, how do I create a new PUBLISH & Move to Trash that I can add to a new metabox?


I have 100+ sql server instances (from sql 2005 to sql 2016) installed in my environment, is there a good way to find when an instance was initially installed?   I tried to check the [master] database creation date, and found (for sql 2012 onward at least) it is always Apr 8, 2003.  The only possible date is [msdb] creation date, which I see it changing for different sql server instances. (I am not sure about this is because I am not sure whether a service patch will change the [msdb] creation date?)  Is there any other reliable way that can indicate the sql server instance creation date? I am open to use of t-sql or powershell to figure it out.  Thanks in advance.

I am interested in determining the ages of all 70+ my servers. I would like to create a growth graph showing when servers and databases were added to the environment either/both monthly or annually. I executed the following query using the SSMS multi-query feature with only partial success.  SELECT [name], create_date FROM sys.databases   It's partial success because the master and model databases return with a date of 'April 8, 2003' when I know that I created some of these servers during the past couple years.  I refresh databases from one server to another several times a week, which appears to be causing issues with the database create date.   Is there a simple method to determine the actual create date for both servers and databases?


Is $\mathbb Z[i/2]:=\{f(i/2) : f(x) \in \mathbb Z[x]  \}$ (smallest subring containing $\mathbb Z$ and $i/2$ )  dense in $\mathbb C$ ?   NOTE : $\mathbb Z [i/2] \ne \mathbb Z + \dfrac i2 \mathbb Z $

Let $\alpha$ be a nonreal algebraic number. I'm interested in conditions that imply that $\mathbb{Z}[\alpha]$ is dense in $\mathbb{C}$. I'm particularly interested algebraic integer $\alpha$.  This is what I know so far:   if there is a $n \in \mathbb{N}$ such that $\alpha^n \in \mathbb{R} \setminus \mathbb{Z}$, then $\mathbb{Z}[\alpha]$ is dense in $\mathbb{C}$; algebraic integers of degree two don't satisfy the condition, although algebraic nonintegers of degree two may.   Many thanks in advance.


I like to know what is the main reason that all C programs should start with the standard function of "int main()"? and why it should be "int" ? Thank you

What is the correct (most efficient) way to define the main() function in C and C++ — int main() or void main() — and why? And how about the arguments? If int main() then return 1 or return 0?  There are numerous duplicates of this question, including:       — For C++, with a very good answer indeed.     Related:


I'm taking Discrete Mathematics and am a little confused on the "empty set" or "null set" defined by ∅.  I understand that ∅ is not a member of {∅} but is ∅ a member of {∅, {∅}} given that there is a null set inside this set?

Herbert in his book "Elements of set theory" on page no 3 says that      we can form the set $ \{ \emptyset \} $ whose only member is $\emptyset $. Note that $ \{ \emptyset \} \neq  \emptyset $, because $ \emptyset \in \{ \emptyset \} $ but $\underline{ \emptyset \notin \emptyset} $·   By the last argument $\emptyset \notin \emptyset$, is he saying that empty set is not a member of or does not belong to empty set  OR  it is a typo and he wanted it to be $ \{\emptyset \} \notin \emptyset $, that set containing empty set is not a member of empty set


Before you say      Oh, this is a duplicate of insert thread here   I've already read some of them, they all say something about a component tag thats being added. Well while messing around with commands and typing "/give" the template says this   /give (player: target) (itemName: Item) [amount: int] [data: int] [components: json]   So since those questions were asked awhile go, did they add components, can we get custom heads now?

This question was recently split into different questions for each workaround. See   meta posts for more information.   Can you use NBT tags in commands? I’ve tried commands that normally work in Java Edition like: give @s minecraft:planks 30 1 {display:{Lore:["Wooden planks"]}} give @s stone_pickaxe{Unbreakable:1b} give @s item_frame{EntityTag:{Invisible:1b}} summon villager ~ ~ ~ {Offers:{Recipes:[{buy:{id:"emerald",Count:5b},sell:{id:"diamond_sword"}}]}} summon tnt ~ ~ ~ {Fuse:20s}


Home folder DEFAULTS to showing hidden files. CTR-H does toggle between showing hidden files and not. But I prefer to NOT have them show in default. Is there a different version that looks more like 14 to show folder options?

How do you show a hidden folder (whose name starts with .) in File Manager a.k.a. Nautilus on Ubuntu?  I am somewhat new to Ubuntu and can't seem to find the "view" menu.


Provided that dark matter coaleces in halos around and within a galaxy and gravity seems to affect dark matter in a similar way as regular matter, would it be possible for dark matter to coalece into a black hole and would not the mass of a black hole include regular matter and dark matter.

Some people speculate that the mysterious dark matter in the universe could be tiny black holes. But on the other side, could dark matter particles attract each other by gravity and finally form a black hole? Since dark matter is even more abundant than normal matter, the dark matter black hole should not be rare.


Let us have the following equation of motion (it might not necessarily correspond to a physical system):  $$\dot{x} + a \cdot x + b \cdot x^2 + c=0.$$  I would like to deduce the corresponding Lagrangian. I have tried multiple combinations but I have not been able to obtain the $\dot{x}$ term.  All the systems I have worked with before had a $\dot{x}^2$ term instead of $\dot{x}$. I have unsuccessfully tried to compare the problem with a damped harmonic oscillator, but the $\dot{x}^2$ term is still missing.  I have solved the equation just in case:  $$x=\frac{A_1 \cdot e^{A_2 t} + A_3}{1 - A_4 \cdot e^{A_2 t}}.$$

Define a physical system when Aristotelian mechanics $F=mv$ instead of Newtonian mechanics $F=ma$.  Then we could have action $I=\int L(q,t)dx$  rather than $\int L(q',q,t)dx$.   Is there an action principle?  Will the formula $I=\int p d q$ still hold? What will be the Hamiltonian and conservation laws look like in this case?


If I vote to close my own Q as dupe, it has no effect other than casting a dupe vote.   But if I then refresh the page, I see that note on top of it asking whether that other question solved my problem.   Clicking on "Yes" there finally lets the Community user close it.  An example where this happened on Ask Ubuntu is .  Why doesn't my first own dupe close vote immediately close my own question instead?

Someone voted to close my question as a duplicate. I agreed, so I cast my close vote (I have enough reputation to vote to close).  . So I expected this to happen.  But it didn't. This confused me — is this not a question I asked after all? No, it is. Maybe I need to reload the page? Nope, the question still isn't closed. Is the asker confirmation feature broken? Well, there's the “This question may already have an answer here” banner at the top. What if I click “That solved my problem!”? Ah, that does close the question.  It turns out that only clicking “That solved my problem!” instantly closes the question. Casting a close vote has a different effect, it's just an ordinary close vote.  Please make casting a close vote equivalent to clicking “That solved my problem!”.


When two singular subjects are connected by "neither...nor", does it take a singular verb or plural verb? Which is more natural and acceptable?  Neither Mary nor Jane is / are beautiful.

In school, I was taught whenever coming across the pattern "either..or" or "neither..nor", we should always consider the noun/pronoun nearer to the verb when deciding which form to use.   For example:      Neither my parents nor John _______ (agree) with that.   In this case, we should use "agrees" instead of "agree" since John is closer to the verb.  Then I have a question. What if when there is only "either" or "neither"?  For example:      There are two particles: quarks and gluons. Neither ________ (detect) in the lab in isolated form yet.   In this case, should I use "has been detected" or "have been detected"?


I come across the following python puzzle:    x=4*[[]] # x is now [[],[],[],[]]   for i in range(len(x)): x[i]+=[i];   print x;   # this returns [[0,1,2,3],[0,1,2,3],[0,1,2,3],[0,1,2,3]]   now if I do instead:    x=[[],[],[],[]];   for i in range(len(x)): x[i]+=[i];   print x;   # this returns [[0],[1],[2],[3]]   The question is, why?  I also find that if the code is changed to     x[i] = x[i] + [i]   then we have in both cases    [[0],[1],[2],[3]]     Does someone know why python behaves in this way?   Edit: the first half of my question is answered in the duplicate reference, and the second half is explained by @joriki below.

I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?


I'm trying to store the first 5 lines from a file in the variable url.  But I get an error   -n5: command not found   fn_all_urls stores the path to the file /home/urls.txt  My Line is:  url=head -n5 ${fn_all_urls} #get first 5 lines in file echo "$url"   I'm using bash on Ubuntu 18.04 64 bit

I want to assign the result of an expression (i.e., the output from a command) to a variable and then manipulate it – for example, concatenate it with a string, then echo it.  Here's what I've got: #!/bin/bash cd ~/Desktop; thefile= ls -t -U | grep -m 1 "Screen Shot"; echo "Most recent screenshot is: "$thefile;  But that outputs: Screen Shot 2011-07-03 at 1.55.43 PM.png Most recent screenshot is:   So, it looks like that isn't getting assigned to $thefile, and is being printed as it's executed. What am I missing?


My Matlab version is R2012a Why in Matlab 1.1-0.2 is not equal to 0.9!!!!!?  This is awful!     >>1.1-0.2 == 0.9      ans =   0

I am writing a program where I need to delete duplicate points stored in a matrix. The problem is that when it comes to check whether those points are in the matrix, MATLAB can't recognize them in the matrix although they exist.  In the following code, intersections function gets the intersection points:  [points(:,1), points(:,2)] = intersections(...     obj.modifiedVGVertices(1,:), obj.modifiedVGVertices(2,:), ...     [vertex1(1) vertex2(1)], [vertex1(2) vertex2(2)]);   The result:  >> points points =    12.0000   15.0000    33.0000   24.0000    33.0000   24.0000  >> vertex1 vertex1 =     12     15  >> vertex2     vertex2 =     33     24   Two points (vertex1 and vertex2) should be eliminated from the result. It should be done by the below commands:  points = points((points(:,1) ~= vertex1(1)) | (points(:,2) ~= vertex1(2)), :); points = points((points(:,1) ~= vertex2(1)) | (points(:,2) ~= vertex2(2)), :);   After doing that, we have this unexpected outcome:  >> points points =    33.0000   24.0000   The outcome should be an empty matrix. As you can see, the first (or second?) pair of [33.0000 24.0000] has been eliminated, but not the second one.  Then I checked these two expressions:  >> points(1) ~= vertex2(1) ans =      0 >> points(2) ~= vertex2(2) ans =      1   % <-- It means 24.0000 is not equal to 24.0000?   What is the problem?    More surprisingly, I made a new script that has only these commands:  points = [12.0000   15.0000           33.0000   24.0000           33.0000   24.0000];  vertex1 = [12 ;  15]; vertex2 = [33 ;  24];  points = points((points(:,1) ~= vertex1(1)) | (points(:,2) ~= vertex1(2)), :); points = points((points(:,1) ~= vertex2(1)) | (points(:,2) ~= vertex2(2)), :);   The result as expected:  >> points points =      Empty matrix: 0-by-2


I'm wondering if it's a good idea to allow casting close votes AND down votes.   Usually, when a user casts a close vote, they will also cast a downvote. This obviously doesn't happen all the time, but based on what I've seen across Stack Exchange, I would say it's fairly common.   Now this doesn't make any sense. Voting to close a question is the act of registering your opinion that the question has problems, and needs to either be edited or closed. Downvoting a question is the act of saying, as the description text says when you hover over the button, 'this question does not show any research effort; it is unclear or not useful.'   Are these two things the same? No. Certainly there can be some overlap, but they aren't the same. For example, you can have a perfectly researched, clear, and helpful question, and it still deserves to be closed because it's off topic for the site it's on. I've seen this many times. I've even seen users downvote a question simply because it was on the wrong SE site, even though it would be perfectly on-topic once migrated.   So, given that close votes and downvotes are the acts of registering two separate opinions, should a user be allowed to register them both? There are certainly questions which deserve to be closed AND downvoted, but not all of them. And if we're perfectly honest, is that one missed down/close vote really going to matter, if the question obviously needs to be deleted/closed? I doubt it.   So this is what I propose: make it so that if someone casts a close vote, they cannot downvote. And vice versa. If they downvote, they cannot vote to close that question.   What are the community's thoughts on this? Am I off my rocker, or is there something to this?

Now that I've reached 3K on SO, I find myself with the awesome power and responsibility (sic) to vote to close. So I've been thinking about the four possible responses to a poor question:   edit comment downvote vote to close   Oddly, I don't see a lot of use for downvoting.   If I can make something of a question by editing it, I do. If I can't, unless it's a giant stinker, I comment. If the comment doesn't yield an improvement, I ask, 'just how awful is this?' If the question's not answerable close. If it is, well, I suppose I could downvote, but somehow, I feel that the posters of such questions get all the punishment they deserve when they don't get useful answers.  "A Giant Stinker" should mean: qualifies under the stated criteria for a close.  Answers are another story. An answer that is actually incorrect to the best of my knowledge get a swift downvote.  In other words, it seems important to me to give rep feedback to answerers, so that people who post actually incorrect answers fail to accumulate rep and acquire a label of legitimacy. On the flip side, bad questions almost always come from people with so little rep that 'whacking them' with a downvote has no real effect.  There's an interesting question of 'downvoting people' versus 'downvoting things.' As per someone who posted an answer, it is questions and answers that get voted. However, I observe that it is people who gain and lose rep.   Of course, once people reach empyrean rep, downvotes are mere mosquito bites, and we just have to hope that they never turn to the dark side. Even the anticipated larger negative scores on downvotes aren't going to put much of a dent into 44K.  All this adds up to an artifact of the rep system. Downvoting a person with 1 rep sends a message but has no practical effect. Downvoting someone with 1K rep is just the same. The only people who really feel a downvote as a crimp in their ambitions are those who are initially climbing the rep hill.  Does this make sense?


I'm running out of slots in my old electrical panel. All of my breakers have a single wire plugged in. Can I free one up by feeding my doorbell low voltage converter into the same circuit breaker that I use for my ceiling lights?

US, Georgia I am adding some new ciruits to add some additional outlets.  The closest place is to run a wire to the main panel box.   My question is, can I connect more than one wire to a breaker and still meet code or do I need to get a new breaker.  Both the wires and plugs are the same rating as the breaker - 15 amp.  Making the assumption that only one wire can be under each screw in the breaker, can I make a junction in the panel box?  IE, one wire to breaker, but two wires to a wire nut connecting them together, or does the junction need to be in a separate box?


Today while I browsed around the SE sites I found an interesting answer on SciFi Meta SE. The answer can be found  if relevant. Since I don't have an account there yet I was prompted to sign up or sign in. So I clicked the link and was redirected to the . Then I clicked on "Confirm and create this account" and was greeted with a , which is obviously a dead end.  How can I create an account on SciFi Meta SE anyway?

Steps to reproduce:   Goto a post on a meta site you don't have account on () Click "add a comment" Click "join this community" Click "confirm and create this account" Receive 404 page not found   I have seen this on multiple site metas (Chemistry and Portuguese).