Why should I use a subdomain structure over a directory structure?
Do subdomains help/hurt SEO?
CSS Margin Collapsing So essentially does margin collapsing occur when you don't set any margin or padding or border to a given div element? If $p$ is congruent to $2 \pmod 3$, how can I prove that all $a$, $1 \le a \le p-1$ are cubic residues $\mod p$? If $p$ is congruent to $2 \pmod 3$, how can I prove that all $a$, $1 \le a \le p-1$ are cubic residues $\mod p$?  Here's what I've done:  $1^3$ congruent to $1 \pmod p$ thus, 1 is a cubic residue, Also $(p-1)^3=(p-1) \pmod p$ implies  $$(p-1)^3 - (p-1) = (p-1)[(p-1)^2 -1] = (p-1)(p^2 -2p) = p(p-1)(p-2) $$ implies $$p|(p-1)^3 -(p-1)$$ Thus  $p-1$ is a cubic residue $\mod p$. Now I don't know how to show for $1\lt a \lt p-1$ are all cubic residues when $p$ is congruent to $2\pmod 3$. Are mounts proficient in armour (barding)? How to dynamically change a web page's title? If $n\ne 4$ is composite, then $n$ divides $(n-1)!$. I have a proof and need some feedback. It seems really obvious that the statement is true but it is always the obvious ones that are a little trickier to prove. So I would appreciate any feedback. Thank you!  Here is what I am asked to prove:     If $n$ is composite then $(n-1)! \equiv 0 \pmod n$.   Proof:  $n$ is composite $\implies n=ab$ where $a,b \in \mathbb{Z}$ and $0&lt;a,b&lt;n$.  Case 1: If $a=b$ then $n=a^{2}$. Now $n \mid (n-1)! \implies a \mid (n-1)!$, so $$\begin{aligned} (n-1)! &amp;\equiv 1\times 2\times \dotsb \times a \times\dotsb\times (n-a)\times\dotsb\times (n-1) \\ &amp;\equiv 1\times 2\times \dotsb\times a \times\dotsb\times -a\times\dotsb\times -1 \\ &amp;\equiv 0 \pmod n \end{aligned}$$  Case 2: $0&lt;a&lt;b&lt;n$.  Then, since $a \mid n$, $b \mid n$ and $n \mid (n-1)!$ we have that $a \mid (n-1)!$ and $b \mid (n-1)!$.  So this implies $(n-1)! \equiv 1\times 2\times \dotsb\times a \times\dotsb\times b\times\dotsb\times (n-1) \equiv 0 \pmod n$, Q.E.D. How to efficiently find positions of duplicates? Maximum number of threads per process in Linux? "I couldn't but laugh" - correct or not? How to avoid duplicating assigned materials when duplicating a mesh? how can I prevent Blender 2.8 from duplicating materials every time (?) I duplicate a mesh. Change default saving folder How to write zero in the unary numeral system In the decimal system: $...-3, -2, -1, 0, 1, 2, 3...$ In the binary system: $...-11, -10, -1, 0, 1, 10, 11...$ In the unary system: $-111, -11, -1, \text{ ??? }, 1, 11, 111...$   I was only able to find a related question but none with an answer so far: Is there an intuitive reason the brachistochrone and the tautochrone are the same curve? The  asks what shape a hill should be so a ball slides down in the least time.  The  asks what shape yields an oscillation frequency that is independent of amplitude.  The answer to both problems is a cycloid.  Is there an intuitive reason why these problems have the same answer?  Proposed operational definition of "intuitive":  Imagine modifying the problem slightly, either to the  (tunnel through Earth), or by taking account of the finite radius of the ball.  If the answer to the original question is intuitive, we should easily be able  to tell whether these modified situations continue to have the same brachistochrone and tautochrone curves. How do I get AMD/Intel Hybrid Graphics drivers to work? On Ubuntu 12.04 my Sony Vaio VPCSE with Intel® HD Graphics 3000 and AMD Radeon™ HD 6630M worked fine with the Catalyst Control Center version 12.6. Also the switching between integrated and discrete graphic card was working.  In both cases, I followed this .  But it is not working on Ubuntu 12.10.   I tested the tutorial with the Catalyst Control Center from the Ubuntu Software Center, the version 12.8 and version 12.9. Always the same problem: After installation process I am able to boot in the login-screen. But after entering the password for my username, only the background-image appears. Unity seems not to be starting. I am only able to reach the context-menu by right clicking the mouse button.  I also tried , but is also does not work for me.  Any ideas what to do to fix this problem?   Update: Same problem on Ubuntu 13.04!  Update: Solution for 13.04 ist not working on Ubuntu 13.10! When a new tag is created, should there be some kind of notification to the user?  This could serve a dual purpose:   To make the user check that this tag is really required.  Is it spelt right? Might there be a more appropriate tag to use instead? - See  To promote the creation of tag wikis.   These are both beneficial to the site.  Making users think twice about their tags reduces the amount of retagging edits that are needed and reduces noise.  Promoting tag wikis means that more new tags would come with explainations, making them more user-friendly for others.  Creating a new tag is a privilidge earned at 1500 reputation.  Hopefully the user has gained a feel for the ethos of SO by this point, and is either enjoying being a contributer or is mainly asking good, well recieved questions.  The user is probably also wanting to contribute to the site further (even if just to gain reputation), and so it makes sense to me that there should be a gentle push towards taking a little bit of time to write a short wiki for the tag you just created.  By no means should this be mandatory, and the precise format of this gentle push is more in the scope of UX guys to think up, but I wanted to see how people felt about some kind of discreet notification.  I thought of two forms this notification could take:  Option 1 - at the time of tagging      Option 2 - after posting      Update: Raphael has suggested in the comments that this could be implemented as a 10K user tool.  While I think that's a good idea on its own, I don't think it should be used instead.  I think that encouraging users with less than 10K to complete wikis for their own tags is likely to get some wikis written because there is a sense of ownership over your own tag, and by giving it a wiki you are giving it a better start in life. As with a child, users will want to equip their tag with the tools it will need to survive in the big wide world. I would like to label an equation with an arbitrary symbol, rather than a number, or letter.  Is this possible? Does the sign of $\Delta x$ matter in this time dilation calculation? How old should you be when you begin Jedi training? No option to remove Bluetooth device in iOS Settings app? I would like to remove my Raspberry Pi from my iPhone 8 (running iOS 11.2.1) as a connected bluetooth device.  Normally, I would go into my Settings -> Bluetooth and select the Info button (a small blue circled "i") to show the "Disconnect" and "Forget Device" dialogs:    Unfortunately, iOS does not give me this option for my device. The bluetooth device list does not contain an "i" for the item, and there is seemingly no other way to disconnect.    How do I unpair this device if there is no button to trigger to the unpair prompt?  Due to work restrictions I cannot completely reset the device. I can always find that in some articles the production of higgs decay written as &quot;$\rm H\to {ZZ}^*\to 4l$&quot;, &quot;$\rm H\to ZZ\to 4l$&quot;, &quot;$\rm H\to Z\gamma^*\to\ldots$” What dose it mean when some particles with a superscript *? Such as “$\rm Z^*, W^*, \gamma^*, \ldots$&quot;. What’s the difference between them and &quot;$\rm Z, W, \gamma$&quot;? Is "do something by date X" inclusive? Possible Duplicate:          For example, if John says:      Return it to me by March 24th.    Does it mean that I need to return it to him before 23:59 p.m. March 24th, or before 23:59&nbsp;p.m. March&nbsp;23rd?