How can I target both :-webkit-full-screen and :moz-full-screen at the same time?
Is it possible to write one CSS rule for several prefixed selectors?
How can you accelerate without moving? Prove that the union of the interior of a set and the boundary of the set is the closure of the set I'll denote closure of A with $\overline{A}$, $A^\circ$ as the interior of A, $\partial A$ as the boundary of $A$ and $A'$ as the accumulation points. I'm trying to prove the following:   $$\overline{A}=A^\circ \cup\partial A$$  Is this a valid proof?  Take $x \in A^\circ \cup \partial A$ then $x \in A^\circ$ or $x \in \partial A$   if $x \in A^\circ$ then $x \in \overline{A}$  if $x \in \partial A$ then $x \in \overline{A} \cap\overline{(X\setminus A)}$ thus $x \in\overline{A} $ so $A^\circ\cup\partial A\subset\overline{A}$  Take $x \in \overline{A}$ then $x \in A' \cup A$ thus $x \in A'\setminus A$ or $x \in A^\circ$  if $x \in A'\setminus A$ then $x \in \overline{(X\setminus A)}$ so $x \in \overline{A}\cap\overline{(X\setminus A)}$ and $x \in\partial A$ so $x\in A^\circ\cup\partial A$  if $x \in A^\circ$ then $x \in A^\circ\cup \partial A$ so $\overline{A}\subset A^\circ\cup\partial A$ identity element of $(D_n ,\gcd)$ How can I derive effect sizes in lme4 and describe the magnitude of fixed effects? What is the relationship between ISO, aperture, and shutter speed? Big Parenthesis in an Equation I have an equation contained inside \[...\], which automatically makes a \sum with sub- and superscripts turn big--so that the summation sign looks awkward inside parenthesis.  Any idea how to make the parenthesis completely enclose the whole summation?  \documentclass{article} \begin{document} We have: \[ \sum_{i=1}^n i = (\sum_{i=1}^{n-1} i) + n = \frac{(n-1)(n)}{2} + n = \frac{n(n+1)}{2} \] \end{document} How to create functions of arbitrary number of variables? Can I visit the UK with an EU permanent residence card? I am non EU national, living in a Schengen country for past 5 years. I hold Indian passport and EU permanent residence card valid for 5 years.   Can i go to UK for few days to visit friends without a visa?  I am aware that UK is not in Schengen, and Schengen visas and residence permits issued by Schengen country is not valid for United Kingdom? But what about the PR card issued by a Schengen country?  I am also aware that EU citizens carrying EU passport have no restrictions to visit UK. Why is echo a shell built in command? $ which echo echo: shell built-in command. $ which ls /bin/ls $ which cat /bin/cat   Why is echo not an independent utility like ls, ps, cat etc? Why is it shell specific? Any good reasons? Ping a site in Python? A "Cantor-Schroder-Bernstein" theorem for partially-ordered-sets If A and B are partially-ordered-sets, such that there are injective order-preserving maps from A to B and from B to A, is there necessarily an order-preserving bijection between A and B ? Insert list of figures in the table of contents Is it possible to create a list of all the figures at the end of a document (this I can do) and make it appear in the table of contents?  So in the the table of content there will be a line saying List of figures ... 19 for example? I read a YA novel in the early 2000s that I think takes place on Earth some time in the future. The human race has been enslaved by some other race, possibly aliens. If I remember correctly, humans were kept as slaves for some purpose and then exterminated at age 16, and I think some girls were kept to breed.  I remember scenes of a band of teenagers walking around sewers fighting these aliens who bled a blue "ichor." The only thing I distinctly remember about the book was that it was the first place I saw the word "ichor."  This is a pretty sorry description; but does anyone have a clue what this book was? Proving that if $G$ has a Hamiltonian circuit, then the line graph $L(G)$ also has a Hamiltonian Circuit I have a graph G = (V, E). I know that the line graph L(G) of G is defined as follows: each vertex in L(G) corresponds to an edge in G, and two vertices are connected by an edge in L(G) if and only if the corresponding edges in G are adjacent.  Now I am trying to (a) prove that if G has a Hamiltonian circuit, then L(G) also has a Hamiltonian circuit, and (b) give an example of a graph G such that G does not have a Hamiltonian circuit but L(G) does.  However, I'm extremely stuck on how to do this, and any help would be greatly appreciated. Thanks so much! How do I handle null or optional DLL struct parameters How to download Bootcamp drivers without Bootcamp assistant? Roots in a polynomial ring How to change text entry in Ubuntu 18.04 I was using Ubuntu 16.04. There it was so easy to change the text entry option. Settings > Text entry.  But when I switch to Ubuntu 18.04 I can't find such option. So how can I write in another language? How to change text entry i.e. by super+shift or something like that? ionice without effect Behaviour of printf when printing a %d without supplying variable name I've just encountered a weird problem, I'm trying to printf an integer variable, but I forgot to specify the variable name, i.e.  printf("%d");   instead of  printf("%d", integerName);   Surprisingly the program compiles, there is output and it is not random. In fact, it happens to be the very integer I wanted to print in the first place, which happens to be m-1.  The errorneous printf statement will consistently output m-1 for as long as the program keeps running... In other words, it's behaving exactly as if the statement reads  printf("%d", m-1);   Anybody knows the reason behind this behaviour? I'm using g++ without any command line options.  #include &lt;iostream&gt; #define maxN 100 #define ON 1 #define OFF 0  using namespace std;  void clearArray(int* array, int n); int fillArray(int* array, int m, int n);  int main() {     int n = -1, i, m;     int array[maxN];     int found;      scanf("%d", &amp;n);      while(n!=0)     {         found=0;         m = 1;         while(found!=1)         {             if(m != 2 &amp;&amp; m != 3 &amp;&amp; m != 4 &amp;&amp; m != 6 &amp;&amp; m != 12)             {                 clearArray(array, n);                 if(fillArray(array, m, n) == 0)                 {                     found = 1;                 }             }             m++;         }          printf("%d\n");          scanf("%d", &amp;n);     }      return 0; }  void clearArray(int* array, int n) {     for(int i = 1; i &lt;= n; i++)         array[i] = ON; }  int fillArray(int* array, int m, int n) {     int i = 1, j, offCounter = 0, incrementCounter;      while(offCounter != n)     {         if(*(array+i)==ON)          {             *(array+i) = OFF;             offCounter++;                }         else          {             j = 0;             while((*array+i+j)==OFF)             {                 j++;             }             *(array+i+j) = OFF;             offCounter++;                    }         if(*(array+13) == OFF &amp;&amp; offCounter != n) return 1;         if(offCounter ==n) break;          incrementCounter = 0;                while(incrementCounter != m)         {             i++;             if(i &gt; n) i = 1;             if(*(array+i) == ON) incrementCounter++;          }            }      return 0; }