If I deleted my Google account, I cannot register a new account with the same name.  How long does Google keep that name taken, before I can register it again?
If I close (is delete an option ?) my Gmail account, will somebody be able to register using my email address and read my mails?  I want to close my Gmail account but I don't want anybody to impersonate me with my old address.  Same question with Yahoo! Mail. Do they allow addresses to be re-used?
I need to prove that the center of $A_n$ is trivial for $n \geq 4$.  $Z(A_3) = A_3$, since $A_3 = \mathbb{Z}/3\mathbb{Z}$ is commutative.  One idea is two use "counting" technique. First of, all we count cojugacy classes of even permutations in $S_n$. It's the classes correspodning to the types $[\lambda_1, ..., \lambda_r]$ where $n \equiv r \mod 2$  Now, the conjugacy class in $S_n$ correspoding to the type $[\lambda_1, ..., \lambda_r]$ splits into two equal-sized classes in $A_n$ if $\lambda_1, ..., \lambda_r$ are distinct odd numbers. If they aren't then it is preserved in $A_n$.  Then we can use "the counting formula"(  ) of elements in each "even" class of $S_n$ and divide one by $2$ if needed.  Still, I'm not sure if it can be done. Seems to be a lot of work there. Maybe there are other, he easier ways? Or, maybe, it is the way, in this case, I wouild appreciate any advices. The situation is my  has been enchanted with .  The creature has      when it dies, return it to his owner’s hand   The enchantment says     When enchanted creature dies, return that card to the battlefield under your control with a +1/+1 counter on it.   Who gets the creature? Me or my rival?  Does the creature ability trigger before or after enchantment? The best free and most up to date phylogenetic tree on the internet? I found phylogenetic tree in wikipedia is lacks of accuracy. It actually confusing with versions. Some terms was not scientifically accurate with dna analysis anymore  So are there anyone know where is the most updated datasource on the internet? How to loop through arguments in Bash ($1 $2 $3 and so forth)? I try to initialize an array in bash-4.2 next way:  ring=() ls -las | tail -n +4 | while read line &gt; do &gt; ring+=("$line") &gt; echo ${ring[-1]} &gt; done 3924 -rw-r--r-- 1 username group 4015716 Mar 23 15:14 script.jar 4 -rw-r--r-- 1 username group 9 Feb 29 12:40 rec.lst 5541 -rw-r--r-- 1 username group 5674226917 Mar 28 15:25 debug.out 8 -rw-r--r-- 1 username group 6135 Mar 25 12:16 script.class 8 -rw-r--r-- 1 username group 6377 Mar 25 11:57 script.java 8 -rwxr-xr-x 1 username group 4930 Mar 8 15:21 script-0.0.0.sh 8 -rwxr-xr-x 1 username group 6361 Mar 28 15:27 script-0.0.1.sh echo ${ring[0]}  echo "${ring[0]}"  echo "${ring[@]}"   What is wrong, why i get empty array after the finish of the loop? Cannot edit posts on iOS app When I try to submit an edit in the iOS app it returns this message:        Text:     Account is not allowed to suggest edits   What happened and can it be fixed please? 18.04: color emoji not showing up at all in Chrome, only partially in Firefox Suppose $f:\mathbb{R}\to\mathbb{R}$ is Borel measurable. I want to show that $\displaystyle \int_a^b f(x)\mathrm dx=0$ for all $-\infty&lt;a&lt;b&lt;\infty$ with $a$ and $b$ rational implies that $f=0$ a.e. I'm really not sure how to approach this problem; any help would be welcome. Pass a PHP string to a JavaScript variable (and escape newlines) In terms of purely set theory, the axiom of choice says that for any set $A$, its power set (with empty set removed) has a choice function, i.e. there exists a function $f\colon \mathcal{P}^*(A)\rightarrow A$ such that for any subset $S$ of $A$, $f(S)\in S.$ Is this correct?  My question then is about proving this fact, so that we do not need to put it as an axiom. Now as per the research done on this single object- Axiom of Choice, I believe here that there should be some falsity in my argument. I do not find the mistake.  For any $S\in \mathcal{P}^*(A)$, since $S\neq \emptyset$, $\exists s\in S$. Define $f(S)=s$. Then $f$ is a choice function.  This was showing me that the axiom of choice is proved, but then why it had been put as an axiom? For example, in  book, the author asserts that      It is a metatheorem of mathematical logic that it is impossible to specify the function that assigns to each non-empty subset of $\mathbb{R}$, an element of itself.     There are several notes and books on axiom of choice, but here I am trying to understand through doing some argument for some problem, where problem actually arises. What does a "CALLBACK" declaration in C do? I was looking through some code from the  library and came across a function declared like this:  LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)   Now, I'm a Delphi coder.  No hablo C muy bien, senor.  But I remember enough syntax from my college courses to read it like this:  Function name is WndProc.  Argument list is pretty self-explanatory.  Function return type is LRESULT.  But what in the world is that "CALLBACK" doing there?  In Delphi, any function can be used as a callback; you just need to pass the right type of function pointer.  Is there any particular reason why C doesn't work that way?  Or does it mean something different? Let $ D = 2^\mathbb{N} $, i.e., D is the set of all sets of natural numbers.   What's the meaning of this definition? Intuitively, I would suggest that $ D = \{1,2,4,...\} $ but the explanation "set of all sets" leads me to the guess that this is wrong. I get different lightning render with the same scene camera setup.  Cycles render (both experimental and supported feature set) gets weaker lightning and needs more energy.  How can I get the same lightning and reflection setup with EEVEE and Cycles? HTML escapes appearing in node titles on bespoke content type — substitutions? What is Reflection in Java Can anyone explain? Convert file contents to lower case I have temp file with some lower-case and upper-case contents.  Input  Contents of my temp file:  hi Jigar GANDHI jiga   I want to convert all upper to lower.  Command  I tried the following command:  sed -e "s/[A-Z]/[a-z]/g" temp   but got wrong output.  Output  I want it as:  hi jigar gandhi jiga   What needs to be in the substitute part of argument for sed? Gedit has a transparent background since upgrade to 16.10 Since I upgraded to from 16.04 to 16.10, gedit has strange new "feature": its background is totally transparent.    Where can this come from ?  Notice I'm using Unity and don't have any specific gnome package installed besides what comes by default. Notice also that in 16.04 I used the Vivacious theme from ravefinity PPA, but I had to go back to Ambiance as Vivacious was broken in 16.10. Maybe it's related.  [EDIT] changing the 'Fonts and Colors' in gedit to any theme other than default (Kate, Solarized, Oblivion, etc..) solves the issue. So there must be a faulty gtksourview file in my home somewhare, but I can't find it... Suppose $f$ and $g$ are entire functions, and $|f(z)| \leq |g(z)|$ for all $z \in \mathbb{C}$, Prove that $f(z)=cg(z)$.   My try :  I consider $h(z)=\frac{f(z)}{g(z)}$. If I prove that $h(z)$ is entire, using the fact that $|h(z)|\leq 1$, the result follows immediately from Liouville's theorem.  To prove that $h(z)$ is entire, I have to prove that $h(z)$ has removable singularities at possible zeros of $g(z)$.  Suppose $g(z_0)=0 \Rightarrow |g(z_0)|=0 \Rightarrow |f(z_0)|=0$, BUT what if $z_0$ be a root of of order $k$ of $g(z)$ (i.e. $f^{(n)}(z_0) = 0 $ for all $ 0 \leq n \leq k-1$) and be a zero of order $m$ of $f(z)$ and $k&gt;m$ ?  And if that's not the case, how to rigorously show that $z_0$ is a removable singularity ?  Thank you all in advance. How can I assign the output of a command to a shell variable? 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 &quot;Screen Shot&quot;; echo &quot;Most recent screenshot is: &quot;$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? In terminal emulation applications, pressing CTRL + Left / Right arrows jumps from one word to the previous or next one. Is it possible to have the same functionality in a Linux console, whether it is in text or in framebuffer modes?  In my configuration, the CTRL + arrow keys are transformed into escaped character sequences and not interpreted.