Difference between &lt;input type="button"/&gt; and &lt;button&gt;&lt;/button&gt; in html5?  &lt;input type="button"/&gt;  &lt;button&gt;&lt;/button&gt;      These two tags gives the same output,but why we use it differently?
When looking at most sites (including SO), most of them use:  &lt;input type="button" /&gt;   instead of:  &lt;button&gt;&lt;/button&gt;    What are the main differences between the two, if any? Are there valid reasons to use one instead of the other? Are there valid reasons to use combine them? Does using &lt;button&gt; come with compatibility issues, seeing it is not very widely used?
Does $x^2 - y^2 = 12345678$ (x,y are integers) have any solutions? How does an arcane focus work with an Eldritch Knight? My PC is an Eldritch Knight. I was wondering what is an Arcane Focus? Do I need to have it in my hand? If I get the War Caster Feat does my arcane focus become obsolete? How can I draw a dot under a symbol in math mode? Pattern matching with LIKE, SIMILAR TO or regular expressions in PostgreSQL I had to write a simple query where I go looking for people's name that start with a B or a D :   SELECT s.name  FROM spelers s  WHERE s.name LIKE 'B%' OR s.name LIKE 'D%' ORDER BY 1   I was wondering if there is a way to rewrite this to become more performant. So I can avoid or and / or like? One or more of the following things happened to me on a Stack Exchange site:   My post(s) were wrongly deleted or locked by a moderator A moderator posted a wrong comment on one of my posts I was suspended, but did not do anything wrong I asked a meta question, but the question was closed and/or deleted A moderator discredited me in public ...   I think a moderator has abused their power, but I feel powerless against them.  What recourse do I have now? What can I do when I feel that a moderator has abused their power, and has been repeatedly unfair in their dealings with me? I'm trying to install Lubuntu on my laptop (sorta old 2005). [Laptop stats: Intel® Celeron® CPU 410 @ 1.46 GHz 1.47GHz, 448 MB of RAM]  I press Install and this message appears:   This kernel requires an x86-64 CPU, but only detected an i686 CPU.  Unable to boot - please use a kernel appropriate for your CPU.   What can I do to install Lubuntu on my computer? I recently upgraded to 12.04 from 11.10 and since upgrading have been unable to log in to my user profile. The upgrade went okay and I can login to a guest session fine but whenever I try to login to my profile, after entering my password, I just return to the login screen.  I've changed my password in Root (passwd &lt;username&gt;) and can log in to tty1 with no issues, it's just in GUI I'm having problems.  I'm using a HP dv7 laptop, 32-bit Ubuntu install, Intel® Core™2 Duo CPU P7350 @ 2.00GHz × 2, Nvidia graphics.  Any help would be appreciated. Nignx - worker_connections are not enough I don't know what is going on. I double value for worker connections but it still return error.  server { server_name xxx.com;  root /var/www/web; index index.html index.htm index.php; error_log /var/log/nginx/error.log; location / { proxy_http_version 1.1; proxy_set_header   Host $http_host; proxy_set_header   X-Real-IP $remote_addr; proxy_set_header   Upgrade $http_upgrade; proxy_set_header   Connection "upgrade"; proxy_cache_bypass $http_upgrade; proxy_pass         http://127.0.0.1:7777; }        listen 443 ssl; # managed by Certbot     ssl_certificate /etc/letsencrypt/live/xxx.com/fullchain.pem; # managed by Certbot     ssl_certificate_key /etc/letsencrypt/live/xxx.com/privkey.pem; # managed by Certbot     include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot     ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot  } server {     listen 80;     server_name xxx.com;     return 301 https://$host$request_uri; # managed by Certbot  }   Everything is okej with this code?  ERROR:  Firstly was:  worker_connections are not enough worker_connections are not enough   Now is  27513#0: accept4() failed (24: Too many open files) 27513#0: accept4() failed (24: Too many open files) 27513#0: accept4() failed (24: Too many open files) 27513#0: accept4() failed (24: Too many open files) In linear regression, when is it appropriate to use the log of an independent variable instead of the actual values? Am I looking for a better behaved distribution for the independent variable in question, or to reduce the effect of outliers, or something else? Is there a limit as to how fast a black hole can grow? How do I export the code documentation in C# / VisualStudio 2008? I have always made a point of writing nice code comments for classes and methods with the C# xml syntax. I always expected to easily be able to export them later on.  Today I actually have to do so, but am having trouble finding out how. Is there something I'm missing? I want to go Menu->Build->Build Code Documentation, but there is no option to do that, there. Properly discontinuous action: equivalent definitions Let us define a properly discontinuous action of a group $G$ on a topological space $X$ as an action such that every $x \in X$ has a neighborhood $U$ such that $gU \cap U \neq \emptyset$ implies $g = e$. I would like to prove that this property is equivalent to, having given $G$ the discrete topology and in the $X$ locally compact Hausdorff case, the map $G \times X \rightarrow X \times X$ given by $(g, x) \mapsto (x, gx)$ being proper (i.e. closed and preimage of compact sets is compact) plus the action being free.  I have managed to prove one direction, that is, if the action is proper and free with $G$ having the discrete topology then it is properly discontinuous. I'm having trouble though with the other direction. Here is an attempt: let's denote by $\rho : G \times X \rightarrow X \times X$ the map $\rho(g, x) = (x, gx)$. Suppose $K \subset X \times X$ is compact. We wish to show $\rho^{-1}(K)$ is compact. Let $(g_i, x_i)$ be a net in $\rho^{-1}(K)$. Then $\rho(g_i, x_i) = (x_i, g_i x_i)$ admits a convergent subnet, so passing to it we may assume $x_i \rightarrow x$ and $g_i x_i \rightarrow y$. Essentially we must now find a way to prove $g_i$ converges, but I can't seem to do this. Any hints? factorization of a^n+1? There is a $C > 0$ such that $\vert f(z)-f(w)\vert \leq C\vert z-w\vert$ for a holomorphic map into $B(0, R)$. Let $0&lt;\delta&lt;r$ and $R&gt;0$, and $a\in\mathbb C$. I want to show that there exists $C&gt;0$ such that for all holomorphic functions $f\colon B(a,r)\to B(0,R)$, we have $$ \vert f(z)-f(w)\vert\leq C\vert z-w\vert $$ for $z,w\in B(a,\delta)$.  I'm not sure how to approach this. I was wondering if I could use that $$ \left\vert\frac{f^{(n)}(a)}{n!}\right\vert\leq\frac{\Vert f\Vert_{C(a,\rho)}}{\rho^n} $$ for some $0&lt;\rho&lt;r$. I also have an expression from biholomorphic maps from $B(0,1)$ to itself, but I'm not sure if I could use that here. Any hints? "Nikki's and Alice's X" vs. "Nikki and Alice's X" Unfair 3 Sided Die Question Say you have an unfair 3-sided die.  Side 1 will be rolled with probability $P_1.$ Side 2 will be rolled with probability $P_2.$ Side 3 will be rolled with probability $P_3.$  Find a formula for the probability that the 8th 3 will be rolled on the 10th roll.  Here is how I started:  $$ \sum_{i=8}^{10}P(T_8 = i) $$  Im just having trouble with that expansion? I have a directory with ~1M files and need to search for particular patterns. I know how to do it for all the files:  find /path/ -exec grep -H -m 1 'pattern' \{\} \;   The full output is not desired (too slow). Several first hits are OK, so I tried to limit number of the lines:  find /path/ -exec grep -H -m 1 'pattern' \{\} \; | head -n 5   This results in 5 lines followed by  find: `grep' terminated by signal 13   and find continues to work. This is well explained . I tried quit action:  find /path/ -exec grep -H -m 1 'pattern' \{\} \; -quit   This outputs only the first match.  Is it possible to limit find output with specific number of results (like providing an argument to quit similar to head -n)? Lightsaber blade "weight" in-universe I'm looking for an idiom or saying that I could use when people are focusing too much on small details and not seeing the big picture.  A couple that come to mind are "being penny-wise and pound foolish" and "rearranging deck chairs on the Titanic". However, the former doesn't fit what I'm thinking of because the present activity might not be wise. The latter implies too much about impending doom.  For example, let's say some company is spending all their time refining a small detail in their product, while ignoring a major opportunity shift in the industry. What phrase could I use there? I was recently reading some Lord of the Rings/Stargate SG-1 crossover fanfiction. It is a guilty pleasure, I admit :) In this story, it was suggested by Col. O'Neill to destroy the Ring using a nuclear device. Truth be told I stopped reading at this point, as it was getting to be a little much even for me.  Obviously, this is not canonical in either universe, but it made me wonder: When Elrond said that "only in the fires of Mt. Doom may it be unmade," was he speaking literally? Or was this merely the only known active volcano in Middle Earth? In other words, was whatever magic that protected the One Ring from damage location-based or did it just make it very resistant to destructive force, and Mt. Doom just happened to be hot enough to do this? I know there is (understandably) little information about such technicalities of how magic works in Middle Earth, but I'll accept any reasonable conjecture/consensus as an answer.