I just noticed I was able to vote on a question that was closed.  I found that a bit strange. Is there any time when you can't vote on a question/answer? i.e. does it ever get locked also?
A post can be locked.   What does it mean to lock a post? Who can lock a post? When should a post be locked?
Are PHP short tags acceptable to use? Proof or disproof that every integer can be written as the sum of a prime and a square. I'm refreshing some algebra and in the beginning chapters of my book I'm presented with the following simple looking problem that I got stuck on:      Prove or disprove: If $n$ is a positive integer, then $n=p+a^2$, where $a$ is an integer and $p$ is prime or $p=1$.   At first I thought $n=13$ would give a nice counterexample, but then I noticed my book defines primes to include the negative primes. Now $13=-3+4^2$ is a solution.   I am allowed to use the fundamental theorem of arithmetic and the division and euclidean algorithms. I tried to express $n$ and $a$ by their prime factorizations, but I didn't get anywhere from there. I would like a hint which direction to take. Am I just missing something silly? java math calculation for coordinates of circle given radius of 1.00 How does vendor restocking work in Fallout 4? I've been looking for 2mm EC ammo and according to the  it is supposed to restock every 48 hours at Arturo. However he has not gotten any new 2mm EC ammo for at least 10 restocks.   Do vendors restock on a random selection of items with some being more likely than others? Is there a max limit to how many different items a vendor will sell so that no new items will be added to stock after this limit is reached? Is there a level limit on what items can be restocked? I bought 2mm EC ammunition once from Arturo so I assume I'm high enough level if that's the case? "find: missing argument to `-exec'" when using "-exec rm -f {}\" Can I force a link to open in a specific browser? Difference between @RemoteAction annotation and ? Can you set custom ringtones for contact groups? In iPhone, you can easily change the default ringtone (Settings → Sounds → Ringtone) and set a custom ringtone for individual people (Contacts → [some person] → Edit → Ringtone).   But can you set a custom tone for a group of contacts? (E.g. "family" or "workmates".)  I think that would be handy—and quite basic functionality, so to speak—but I couldn't find a way to do this through the iPhone UI. Is it possible at all (without jailbreaking)? Why is RAM not put on the CPU chip? Modern CPUs are very fast compared to all things external, including memory (RAM).   It is understandable, since CPU clock frequency has reached a point where it takes several clock ticks for an electric signal simply to run from from the CPU through the bus to RAM chips and back.   It also complicates life on many levels: multi-level cache hierarchies are built to deliver data closer to the CPU, which in turn require complex synchronization logic in the chip. Programs must be written in a cache-friendly way to avoid wait cycles while data is fetched.   Many of these problems could be avoided if a significant amount of RAM was located directly on the CPU chip. It doesn't have to an exclusive arrangement: maybe put 1-4 GB on the chip, depending on its class and allow additional memory installed separately.   I'm sure there are good reasons Intel, AMD and the like are not doing this. What are these reasons? Is it that there's no room to spare on the chip? Let $x, y$ and $z$ be real numbers such that $x^2+ y^2+ z^2= 1$. Find the   maximum and minimum values of $2x + 3y + z$ .       How can I able to solve the problem? Thanks for your help. I am trying to update Xcode to 8.0. My OS is 10.11.6 El Capitan. However I am getting:     We could not complete your update   There is not enough disk space available to install the product.   I have got 14.22 GB free space. How much do I need?  UPDATE: I do not know the exact figure, though I did manage to update with 17.21 GB free space later on. How can I make a gameObject "stick" to another gameObject after it has collided with it? How can I make a gameObject "stick" to another gameObject after it has collided with it? Right now the gameObject just passes through! [C#] What does the function f: x ↦ y mean? I am doing , and am having a few problems with function notation. I understand the form f(x).  What does the form f: x ↦ y mean? Could you also give one or two examples?  And, if possible, state your source. Thank you. Influence of the scale factor on the projection I can successfully tether my Mac (10.7.3) to my iPhone4 (5.0.1) via wifi, no problem, been doing it for months.  However, when I try to tether via bluetooth instead, I can't seem to see the internet from my mac.  Network Settings reports a green light for Bluetooth PAN, but my browser can't connect to anything at all.  My Mac reports very similar IP addresses for both, starting with 172.20.10 and differing only in the last octet.  Any idea why I can't successfully tether via bluetooth? Can the union axiom be weakened? Elsevier actions following US sanctions on Iran When I add a mirror modifier it sometimes doesn't mirror correctly, giving me an overlapping mesh. How can I fix this? What can cause a question to be bumped? What can cause a question to be "bumped" to the first page in the Active tab of a Stack Exchange site? (Changing the "Last Active" date.)  . Upgrade to the specific php 7.1/7.2 from php 7.0 in Ubuntu 16.04 How can I upgrade to php 7.1 from php 7.0 in ubuntu 16.04 ?  If I do a php -v I get this message:  PHP 7.0.8-0ubuntu0.16.04.3 (cli) ( NTS ) Copyright (c) 1997-2016 The PHP Group Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies     with Zend OPcache v7.0.8-0ubuntu0.16.04.3, Copyright (c) 1999-2016, by Zend Technologies