They walked past a mossy tree stump. Harry could hear running water; there must be a stream somewhere close by. There were still spots of unicorn blood here and there along the winding path.        "You all right, Hermione?" Hagrid whispered. "Don' worry, it can't've gone far if it's this badly hurt, an' then we'll be able ter –– GET BEHIND THAT TREE!"        Hagrid seized Harry and Hermione and hoisted them off the path behind a towering oak. He pulled out an arrow and fitted it into his crossbow, raising it, ready to fire. The three of them listened. Something was slithering over dead leaves nearby: it sounded like a cloak trailing along the ground. Hagrid was squinting up the dark path, but after a few seconds, the sound faded away.        "I knew it," he murmured. "There's summat in here that shouldn' be."        "A werewolf?" Harry suggested.        "That wasn' no werewolf an' it wasn' no unicorn, neither," said Hagrid grimly. "Right, follow me, but careful, now."       They walked more slowly, ears straining for the faintest sound. Suddenly, in a clearing ahead, something definitely moved.    (Harry Potter and the Sorcerer's Stone)    The bold part seems to be not a double negation but a dialect. Is this right?
In my native language, double negations "cancel out". I have been trying to learn English using movies and such things, but double negation confuses me. I see instances when double negation cancels out, and some when they do not.  For example, "I haven't got no money" is interpreted as "I have no money." "There wasn't anyone who didn't enjoy the party" is interpreted as "Everyone enjoyed the party."  Is this context dependent? If so, how does one decide which interpretation is correct?
Einstein-Hilbert action as an effective field theory I have read the following statement:      "The Einstein-Hilbert action can be seen as an effective field theory: setting $g_{\mu\nu}= \eta_{\mu\nu}+h_{\mu\nu}$, one gets a free Lagrangian for the field $h_{\mu\nu}$ plus interactions."   Now, how is it possible to define all the interaction terms?  EDIT: I ask apologize if my statement was appeared unclear: I have created a  which is more precise; please don't continue to consider seriously this one. Proof by induction that $ 169 \mid 3^{3n+3}-26n-27$ $ 169$ | $3^{3n+3}-26n-27$ ?  Fulfilled for $n=0$. Induction to $n+1$: An integer $x$ exists so that  $ 169x= 3^{3n+6}-26n-27-26$ $ 169x= 27*3^{3n+3}-26n-27-26$ $ 169x= 26*3^{3n+3}+3^{3n+3}-26n-27-26$  An integer $m$ exists so that   $ 169x= 26*3^{3n+3}+169m-26$ ($ 13x= 2*(3^{3n+3}-1)+13m$)  Now I'm stuck although it looks simple. Thanks for any input in advance. Etiquette for username changes I'm thinking of changing my username to my real name. Given that I have a presence on some of the sites here (mostly codegolf), what etiquette should I follow when choosing my new name?  As my username is currently Quincunx, I'm thinking of changing it to MyRealName (formerly Quincunx). Or perhaps MyRealName (né Quincunx). Maybe just MyRealName (Quincunx). If I do use these usernames, will people be able to recognize who I am? Or is there already a standard way to change usernames (such as relying on the profile picture)? pgfplots external with large dataset (lualatex?) I have fairly large datasets with densely strucutred data that i cant downsampe much without loosing structure. I use TexMaker on Ubuntu 14.04LTS. I use   \usepackage{tikz,pgfplots,pgfplotstable} \pgfplotsset{compat=1.9} \usepgfplotslibrary{external} \tikzexternalize   and   \tikzsetnextfilename{figs/test1}   to externalize the figures. This works good compiling with pdflatex -shell-escape. But as the data becomes to large I am out of memory. I am trying to compile using LuaLaTeX -shell-escape instead of pdfLatex but get the following error message:   ! Package tikz Error: Sorry, the system call 'pdflatex -halt-on-error -interact ion=batchmode -jobname "figs/test1" "\def\tikzexternalrealjob{article}\input{ar ticle}"' did NOT result in a usable output file 'figs/test1' (expected one of . pdf:.jpg:.jpeg:.png:). Please verify that you have enabled system calls. For pd flatex, this is 'pdflatex -shell-escape'. Sometimes it is also named 'write 18' or something like that. Or maybe the command simply failed?   so pgfPlots seem to call pdfLatex without the appropriate -shell-escape flag and without me specifying it. How can i get this to compile in LuaLatex? or can i compile only the figures in LuaLatex and the rest in pdfLatex (the opposite of what is happening now)? I found  and  example but neither helped me...  Thankfull for help and i am also thankful for any general advice that can help me resolve the problem of ploting larger data sets in pgfplots.   Cheers /J why does files (nautilus) open a new window although there's one already open? When I click on "files" in the launcher it opens another window although the normal action is to maximize the window already open. It doesn't always do that. Is it a bug? Let $a,b,c\in\mathbb{R}^*_+$, $abc=1$.  How can i show that $\left(a-1+\frac{1}b\right)\left(b-1+\frac{1}c\right)\left(c-1+\frac{1}a\right)\leq1$ ?  I got $\left(ab-b+1\right)\left(bc-c+1\right)\left(ca-a+1\right)\leq abc=1$, but i can't go any further ...  If i expand it :   $2-ab-\frac{b}a-c-ac-\frac{a}c-b+2a+\frac{2}a-bc-\frac{c}b-a+2b+\frac{2}b+2c+\frac{2}c-4$  Which gives using $c=\frac{1}{ab}$ :   $5ab-\frac{b}a-\frac{1}{ab}-a^2b+\frac{1}a+b+\frac{1}b-2$ How to clear the interpreter console? Like most Python developers, I typically keep a console window open with the Python interpreter running to test commands, dir() stuff, help() stuff, etc.  Like any console, after a while the visible backlog of past commands and prints gets to be cluttered, and sometimes confusing when re-running the same command several times.  I'm wondering if, and how, to clear the Python interpreter console.  I've heard about doing a system call and either calling cls on Windows or clear on Linux, but I was hoping there was something I could command the interpreter itself to do.  Note: I'm running on Windows, so Ctrl+L doesn't work. I can't download apps from the Play Store on my Android device (maybe due to a network issue), so I'm wondering how could I download the APK file of an app on my PC from ? In what cases does the gerund stemming from a transitive verb take the direct object of that verb and when is a prepositional complement used?  For example:    Brown's deft painting of his daughter is a delight to watch (it is a delight to watch while Brown deftly paints his daughter). Painting his daughter is an outlet for his energy. Securing safety for prisoners is the main problem for the penitentiary system. The widely discussed problem of the securing of prisoners' safety was given priority. Which experiments prove atomic theory?  Sub-atomic theories:   atoms have: nuclei; electrons; protons; and neutrons. That the number of electrons atoms have determines their relationship with other atoms.   That the atom is the smallest elemental unit of matter - that we can't continue to divide atoms into anything smaller and have them retain the characteristics of the parent element. That everything is made of atoms.     These sub-theories might spur more thoughts of individual experiments that prove individual sub-atomic theories (my guess is more was able to be proven after more experiments followed). Why does Ubuntu not allow the GUI users to login as root at the time of system start up like administrator in Windows?  Why they are restricting us to login only through the terminal? I am using Ubuntu 12.04.  My /etc/network/interfaces file consists of:    # The loopback network interface   auto lo   iface lo inet loopback     # The primary network interface   auto eth0  iface eth0 inet static   address 192.168.1.58   gateway 192.168.1.1 network 192.168.1.0   broadcast 192.168.1.255 dns-nameservers 66.212.63.228 66.212.48.10     I ran the command: /etc/init.d/networking restart  Which responded with:   *Running /etc/init.d/networking restart is deprecated because it may not enable again some interfaces   *Reconfiguring network interfaces...   RTNETLINK answers: File exists   Failed to bring up eth0   [ OK ]     Next I ran ping google.com and received:    ping: unknown host google.com   I am not sure if my interfaces refreshed. How do I properly configure my network with my static DNS addresses? A friend asked me last week how to enumerate or list all variables within a program/function/etc. for the purposes of debugging (essentially getting a snapshot of everything so you can see what variables are set to, or if they are set at all). I looked around a bit and found a relatively good way for Python:   #!/usr/bin/python                                                                                                                                                                                                                            foo1 = "Hello world" foo2 = "bar" foo3 = {"1":"a",         "2":"b"} foo4 = "1+1"  for name in dir():     myvalue = eval(name)     print name, "is", type(name), "and is equal to ", myvalue   which will output something like:   __builtins__ is &lt;type 'str'&gt; and is equal to  &lt;module '__builtin__' (built-in)&gt; __doc__ is &lt;type 'str'&gt; and is equal to  None __file__ is &lt;type 'str'&gt; and is equal to  ./foo.py __name__ is &lt;type 'str'&gt; and is equal to  __main__ foo1 is &lt;type 'str'&gt; and is equal to  Hello world foo2 is &lt;type 'str'&gt; and is equal to  bar foo3 is &lt;type 'str'&gt; and is equal to  {'1': 'a', '2': 'b'} foo4 is &lt;type 'str'&gt; and is equal to  1+1   I have so far found a partial way in PHP (courtesy of ) but it only lists all variables and their types, not the contents:   &lt;?php // create a few variables $bar = 'foo'; $foo ='bar'; // create a new array object $arrayObj = new ArrayObject(get_defined_vars()); // loop over the array object and echo variables and values for($iterator = $arrayObj-&gt;getIterator(); $iterator-&gt;valid(); $iterator-&gt;next())         {         echo $iterator-&gt;key() . ' =&gt; ' . $iterator-&gt;current() . '&lt;br /&gt;';         } ?&gt;   So I put it to you: how do you list all variables and their contents in your favorite language?    Edit by : I propose this question follows the spirit of a little "". If you do not agree, just edit and remove the tag and the link. How to add a new kernel to grub2 How can we add a kernel to grub2? i knew the stuff we could do with the former versions, but it seems to have changed. What files should we edit? The Setup: Let's say we want to study a Euclidean $\mathrm{CFT}_2$ on $\mathbb R^2$ with coordinates $\sigma^1$ and $\sigma^2$ and metric   $ds^2 = (d\sigma^1)^2+(d\sigma^2)^2$.    It seems to me that in the usual discussion (e.g. di Francesco, Ginsparg, Polchinski), one proceeds to consider an analytic continuation of the CFT to $\mathbb C^2$ with coordinates $z^1, z^2$ and complex metric  $ds^2 = (dz^1)^2+(dz^2)^2$  and then, one performs the coordinate transformation $z = z^1+iz^2$ and $\bar z = z^1-iz^2$.  In this way the coordinates $z$ and $\bar z$ can be considered "independent" because they are coordinates on a complex two-dimensional manifold.  Also, in these coordinates the metric becomes  $ds^2 = dz\,d\bar z$  and it becomes clear that conformal mappings consist of mappings: $(z, \bar z)\to (f(z), g(\bar z))$.  My confusion is this: Since our original theory was on $\mathbb R^2$, books say that when we do calculations, we should consider the physical theory as living on the copy of $\mathbb R^2$ embedded in $\mathbb C^2$ given by the condition $\bar z = z^*$.  But consider the mapping $(z, \bar z)\to (z^2, \bar z)$.  This is a conformal mapping on $\mathbb C^2$, but it does not map the surface $\bar z = z^*$ to itself; for example the point $(z, \bar z)=(2,2)$ gets mapped to the point $(z^2, \bar z) =(4,2)$ and $2$ is clearly not equal to $4^*$.  In particular, it seems to me that analytic continuation to a CFT on $\mathbb C^2$ enlarges the set of mappings one can have, so what relevance does it really have to the original CFT on $\mathbb R^2$? Proving $\, a^b = (a\bmod n)^b\, \pmod{\!n}\ $ [Congruence Power Rule] I am working on a problem I am pretty close to solving but I can't figure out the last part. I used some algebraic manipluation to break the problem down. The problem is:     Show that the following congruence is true      a^b = ((a mod n)^b) (mod n)      for any positive integers a, b, and n.      Hint: Number a can be written as a = q*n + r, where q = floor brackets a/n, and r = a mod n.   My attempt it:     (q*n +r)^b = ((a mod n)^b) * (mod n)      (q*n)^b + (a mod n)^b = ((a mod n) ^b) * (mod n)      (a)^b -(r)^b = ((a mod n) ^b) * (mod n)      (a)^b = modn  ----> divided by ((a mod n)^b)   Am I doing this correctly and if so how can I prove this is true? Is there a trick I am missing? I think that by simplifying it further I would just keep going in a loop.  Thanks! Evaluate these infinite products $\prod_{n\geq 2}(1-\frac{1}{n^3})$ and $\prod_{n\geq 1}(1+\frac{1}{n^3})$ What is   $\prod\limits_{n\geq 2}(1-\frac{1}{n^3})=?$ $\prod\limits_{n\geq 1}(1+\frac{1}{n^3})=?$   I am sure about their convergence. But don't know about exact values. Know some bounds as well. For example first one is in interval (2/3,1) and second one is in (2,3). Can I use dispensers or droppers to auto-replant crops? Does GTA V Online Network Merge Xbox 360 and PS3 players? I know what you're thinking: "of course it has, for example, it can be used to tell you how many times you can go around a circle". But that isn't really true, now is it? You'd be dead or the world would go under long before an infinite amount of loops had been reached.  Are there any practical applications for the concept of infinity? Is it a useful concept in maths at all?  I know that Donald E. Knuth has argued that for all practical purposes, a very, very large number has the same effect as infinity, in his book "Things a Computer Scientist Rarely Talks About" (can't remember the exact quote, nor find it online, unfortunately).  Examples are appreciated.