There have been many questions that ask if a user is allowed to cross-post a question on multiple sites, and the general conclusion is that they are not allowed to do so. However, sometimes there are questions which are asked on multiple sites by different users not knowing another SE site had an answer already, where it is on topic on both sites, that have some overlap. What is the policy for such questions? Should they be closed on one site, migrated, or is each site independent enough to allow the question to remain on both sites?
What's the right course of action for cross-site duplicates?  There are two flavors:   A question is posted which belongs on another site and ends up already having been asked there. I can't find an example right now, but it's bound to happen soon if it hasn't already. The same question is posted in two places at the same time. Take  for example, which is a duplicate of , posted within a half hour of each other by the same user.   Possible actions:   Move it to the proper site and close it once it gets there as a duplicate. Provide a way to close it right away as a cross-site duplicate, without moving it first. Flag it and let a moderator merge them. Close it as "no longer relevant" or something else.   Additionally, flavor 2 is a bit of a special case; perhaps the question really spans both sites in terms of content and intended audience. Should multiple-postings in this case be allowed? If so, should they somehow be linked to each other? If not, how do we avoid a migration war?
Combinatorial argument for $\sum\limits_{k=i}^{n}\binom{n}{k}\binom{k}{i} = \binom{n}{i}2^{n-i}$ Can bounties be awarded multiple times by the same person on the same question? Is there any restriction to prevent multiple bounties ( not simultaneously) being awarded to different answers on the same question ?  i.e., on a question  -  I want to set multiple bounties since I've received 2 awesome answers. Can I set award a bounty on answer A first, and then set the bounty and award it to answer B ? How to install PostgreSQL 9.2 with PostGIS 2.0 on Ubuntu 11.10 (or higher)? Is there a way to view &amp; modify the code of standard lightning components that are visible when editing the Napili template in the community builder. I was wondering if I could modify some of the code and use it as lightning out. This is my code:  import datetime today = datetime.date.today() print(today)   This prints: 2008-11-22 which is exactly what I want.  But, I have a list I'm appending this to and then suddenly everything goes "wonky". Here is the code:  import datetime mylist = [] today = datetime.date.today() mylist.append(today) print(mylist)   This prints the following:   [datetime.date(2008, 11, 22)]   How can I get just a simple date like 2008-11-22? I would like my JSON output in Ruby on Rails to be "pretty" or nicely formatted.   Right now, I call to_json and my JSON is all on one line.  At times this can be difficult to see if there is a problem in the JSON output stream.  Is there way to configure to make my JSON "pretty" or nicely formatted in Rails? Vector spaces for the irreducible representations of the Lorentz Group How to concatenate multiple lines of output to one line? Why did Voldemort hide two Horcruxes in Hogwarts? Most of you if not everybody will agree that the stronger the gravitational pull, the faster an object will fall. For example, on a planet with 50 times the gravity of Earth, any object will hit the ground on that planet much quicker than it would on Earth. So taking all of these into the equation, does it mean that at a blackhole, an object will fall at an infinite speed because of the infinitely strong gravitational pull of the blackhole? Apostrophes and double quotes don't show up until I type the next letter in Windows XP, when I type an apostrophe ', or  ", no character is displayed.  If I type another character, the apostrophe or dumb quote and the next character appear at the same time.  This happens with double quotes ", apostrophes ' and tilde ~ characters.  What could possibly be causing this?  This occurs in all applications I have tested - wordpad, firefox, ms word etc. Where does "pay through the nose" originate? How do I get the Glare node to output transparent instead of Black background This is what I have so far:  The rendered image has a transparent background, but the glare filter creates an output with a black background, so after merging the two togheter, the background turns black but I need it to be transparent, what can I do? The special linear group $\text{SL}_n(\mathbb{R})$ is its own commutator Let $SL_n(\mathbb{R})$ be the set of $n\times n$ matrix with determinant one. Where can I find a proof that $[SL_n(\mathbb{R}),SL_n(\mathbb{R})]=SL_n(\mathbb{R})$? I've seen this result mentioned in several places, but couldn't find a proof.  For reference, the commutator $[SL_n(\mathbb{R}),SL_n(\mathbb{R})]$ is defined as the group generated by the set of all elements of the form $a^{-1}b^{-1}ab$, with $a,b\in SL_n(\mathbb{R})$. How to show that $7\mid a^2+b^2$ implies $7\mid a$ and $7\mid b$? For my proof I distinguished the two possible cases which derive from $7 \mid a^2+b^2$:   Case one: $7\mid a^2$ and $7 \mid b^2$ Case two (which (I think) is not possible): $7$ does not divide $a^2$ and $7$ does not divide $b^2$, but their sum.  I've shown that case $1$ implies $7\mid a$ and $7\mid b$, so I just have show that case 2 isn't possible - I'll be happy for any input.  MfG, Karl I'd like to have a horizontal line extending from the end of the text on a line to the right margin. So far I've found \hrulefill and \leaders\hrule\hfill, but these draw a line that's flush with the baseline of my text — how can I get it to be vertically centered? How does JavaScript .prototype work? Should flour be thrown out past its expiry date? What does "off of" mean? I have read a sentence from “Diary of a Wimpy Kid 4”:     The teachers have really been cracking down on kids copying off of each other this year.   How to understand "off of"? Please parse it. What are the fundamental differences between the mainstream *NIX shells and what scenarios might prompt you to use one over the other?  I understand that some of it probably comes down to user preference but I've only ever used Bash and I'm interested to hear where another shell might be useful. Also, is there an impact on user-written shell scripts when running under one shell or another or is it simply a matter of changing the shell at the top of the file?  My instinct says it's not that easy.