What's the difference between "He is no fool" and "He is not a fool"?
Negation in English
What causes javac to issue the "uses unchecked or unsafe operations" warning For example:  javac Foo.java Note: Foo.java uses unchecked or unsafe operations. Note: Recompile with -Xlint:unchecked for details. Star vs Heart icon to represent save as a favourite I am working on a mobile app that involves the user saving a favourite location. I wanted to use an icon to represent that feature, but I'm not sure which one is better – a star or a heart icon.  Some say heart icon tends to increase the rate of productivity, and some say they are used to a star icon to 'save' or 'bookmark' something.  What do go you guys think? How do I change the "Selected Items" color? I was trying to change the selected items color from the default orange to something else, however, the option isn't there, as it used to be in the Appearance properties in previous versions of ubuntu. Any idea where it could be in the beta? Im using a program called Daisy Disk to see what is taking up space in my Mac and I find that the /cores directory is taking up 77gb.   Is that a problem? Can I get rid of it to regain the space? How can I find $\gcd(a^m+1,a^n+1)$ with $a,m,n$ positive integers?    I have this idea:  Let $d=\gcd(m,n)$. Then there exist positive integers $x,y$ such that $mx-ny=d$ (WLOG). We shall find $G=\gcd(a^m+1,a^n+1)$.  If $m,n$ are odd, then $d$ is odd, therefore one and only one of $x,y$ is even. We have:  $$a^{ny}(a^d+1)=a^{mx}+a^{ny}=(a^{mx}-1)+(a^{ny}+1)=(a^{mx}+1)+(a^{ny}-1).$$  If $x$ is even and $y$ is odd, then $a^{m}+1\mid a^{mx}-1$ and $a^{n}+1\mid a^{ny}+1$, therefore $G\mid a^{ny}(a^d+1)$. If $x$ is odd and $y$ is even, then $a^{m}+1\mid a^{mx}+1$ and $a^{n}+1\mid a^{ny}-1$, thus $G\mid a^{ny}(a^d+1)$. However, since $\gcd(a^m+1,a^{ny})=\gcd(a^n+1,a^{ny})=1$, so $\gcd(G,a^{ny})=1$, hence $G\mid a^d+1$. We also have $a^d+1\mid a^{m}+1$ and $a^d+1\mid a^{n}+1$, so $a^d+1\mid G$. Thus $G=a^d+1$.  If $v_2(m)=v_2(n)=v_2(d)=k&gt;1$, then there exist some odd numbers $m_1,n_1,d_1$ such that $m=2^km_1,n=2^kn_1,d=2^kd_1$. We shall have $m_1x-n_1y=d_1$, so one and only one of $x,y$ is even, and we can use the same argument when $m,n$ are odd, so $G=a^d+1$.  However, if $v_2(m) \neq v_2(n)$, I cannot find any solutions for this. I think that $G \in \{1,2\}$, but I cannot prove or disprove it. How can I find $G=\gcd(a^m+1,a^n+1)$ if $v_2(m) \neq v_2(n)$ ? Moreover, is there anything from my arguments that can be improved ? My son has been playing Minecraft on our home computer for a couple of years now.  He just got an iPad Mini 2 for his birthday. Is it possible to transfer his game and his saves onto his iPad Mini 2? Georeferencing vector PDF/SVG/DXF linework using QGIS? I want to  create a small web application to visualize election results on a per poll site basis for my city. The result is going to be very similar to what has been done for Berlin . Hopefully this helps in understanding what I'm going for.  The election raw data on the scale I need is published and I know how to visualize this on the grounds of a shapefile with separate polygons lining out the election districts. My problem is - as you could probably guess - that something like this doesn't already exist.  What actually is published though, is a PDF file lining out the borders of the districts I'm interested in:   I'm not keen on redrawing the linework myself, so I'm looking for a way to make a shapefile out of this. Luckily, the PDf includes the linework as separate vector objects, I extracted these into a SVG file:   I already tried converting the SVG to a DXF and importing it into qgis 2.0.1. This actually works, but (as expected) places the vectors in the atlantic ocean and I can't find a way to edit it and fix this.  What can I do now to georeference these vectors with open source tools and finally produce a shapefile? Number of ways to distribute 5 distinguishable balls between 3 kids such that each of them gets at least one ball How many ways are there to distribute 5 distinguishable balls between 3 kids such that each of them gets at least one ball?   My approach is $ \binom{5}{3} 3! $ + $ \binom{2}{2} \binom{3}{2}2!$ which is equal to $66$? Multiple standard input? How? I'm having trouble understanding the wording of one of my homework questions. Since this question appears early in the chapter, I have a feeling that I'm misinterpreting it.  Give a finite automaton that that accepts the following language: The language over $\{a, b\}$ of any even number of $a$'s and any odd number of $b$'s.   I'm having trouble with the usage of "and". Is it asking for an FA that accepts any string that is either an even number of $a$'s or an odd number of $b$'s, e.g. $aa$, $bbb$, $aaaa$, etc, but not accept strings like $aabbb$, $abbab$.   Or, is it asking for an FA that accepts any string that contains an even number of $a$'s or an odd number of $b$'s, e.g. $aabbb$, $ababb$, etc.   The first case is relatively simple, but I've been struggling with the second. I haven't even managed to convince myself that it is a regular language (because I haven't been able to come up with a regular expression that matches it).   My questions: Which interpretation seems most likely. Is the second case a regular language, if so, give a regular expression that recognizes it. Proving the identity functions is continuous iff $\tau_1\supseteq\tau_2$ Exercise: Let $\tau_1$ and $\tau_2$ be two topological spaces on a  set $X$. Then $\tau_1$ is said to be a finer topology than $\tau_2$ if $\tau_1\supseteq\tau_2$. Prove the identity function $f:(X,\tau_1)\to (X,\tau_2)$ is continuous if and only if $\tau_1$ is a finer topology than $\tau_2$.  Attempted proof: Let $A\in\tau_1$. If $f$ is continuous then $\exists B\in\tau_2$ such $f(A)\subset B\implies A\subset B$ for any $A\in\tau_1$ such that all open sets of $\tau_1$ are open sets of $\tau_2$ hence $\tau_1\supseteq \tau_2$. If $\tau_1$ is a finer topology than $\tau_2$, for any $B\in\tau_2\implies B\in\tau_1$ which implies that $f^{-1}(B)=B$, then $B\in\tau_1$ which proves $f$ to be continuous. Questions: Is my proof right? If not. What is wrong? What are alternatives? Thanks in advance! I was looking at  and I didn't realize that Minecraft had some Easter eggs in it. Besides the Christmas chest Easter egg, and the sheep Easter egg, what else is there? Link renders differently on client and server side when preceded by a special character When editing a question on , I observed that a link which was not rendered in the post was hyperlinked in the edit preview (see pictures below). I tried reproducing it in the  to see if this also happens when the post is posted for the first time and observed the same. It seems to be a bug after the shift to CommonMark, leading to the different rendering of links on client and server-side. A link following a special character (without any space) is not hyperlinked in the post but is hyperlinked in the preview. A link separated from the special character with a white space appears to have no such problem. (see pictures below and my ). Link not hyperlinked in post  Same link hyperlinked in preview First week of August in Scotland : What kind of clothes to pack? In a couple of weeks I will be going to Edinburgh, Scotland. I've been told that the weather is very unpredictable throughout the year. Can you suggest what I should pack as regards clothes? How to evaluate $\int_{0}^{\infty}\exp(-x^2-1/x^2)dx$? Question :  $$\int_{0}^{\infty}\exp(-x^2-1/x^2)dx=?$$  I think the answer is $\sqrt{ \pi/2 \cdot \exp(-2)}$  If I change $-x^2-1/x^2$ to $-(x-1/x)^2-2$ then the above integral becomes    $$\exp(-2)\int_{0}^{\infty} \exp(-(x-1/x)^2)dx$$   integral of $\exp(-x^2)dx$ from $0$ to infinity = square root of $\pi/2$, but then is the   integral of $\exp(-(x-1/x)^2)dx$ from $0$ to infinity=integral of $\exp(-x^2)dx$ from $0$ to infinity ? String answer1 = "yes"; if (answer1 == "yes") gives false. Why? Why is $1 in a function not printing the script's first argument? Why doesn't echo $1 print $1 in this simple bash script?    #!/bin/bash # function.sh print_something () { echo $1 } print_something  $ ./function.sh 123  -&gt; why doesn't it print '123' as a result? I am working on a game and would like to include a few jump scares. So here is a rather simple question — What makes a good jump scare and when and how should they happen? Product of quotient maps and quotient space that is not Hausdorff I am looking for easy(!) counterexamples that the product of two quotient maps is not necessarily a quotient map and that the quotient space of a Hausdorff space is not necessarily Hausdorff. Flattening iterator