I'd like to install mplayer but I've been told that I got to enable "unvierse" repository, where and how can I do that ? any help will be highly appreciated
How do I get to the Universe Repository in supported versions of Ubuntu?
My bibliography (made with biblatex) has all items close to each other. I would like to introduce some space between them, e.g. half a line.  How can I do this? Flawed proof that all positive integers are equal Often (via Google Now, or when searching for a solution to some problem), I'll open a question from a non-favourite site in the app. Sometimes, I'd like to see what else is going on in the site where the question was posted. Currently, I have one of two ways:   Via tag icon:   Click one of the tag icons beneath the title Delete the [tag] text (at which point, thankfully, the sorting changes to Active from Votes).  Via manually searching for the site, which is more cumbersome. I type in hard and Hardware Recommendations is the fourth entry (below Ask Different, Raspberry Pi and Arduino)! This more annoying for meta sites, where I have to pick Meta from the dropdown menu.   Can I pretty please have a way to head to the site directly from the question? Maybe:   the site name in the top bar could become clickable and lead to the site, or an option in the More menu?     This would be especially useful for Meta sites, where questions posted around the same time could be related. Interestingly enough, most questions that Google Now are for metas of sites I visit on occasion, but haven't pinned to the list. Suppose $f:[0,1] \to (0,\infty)$ is a Riemann integrable function. Prove that the integral of the function from $0$ to $1$ is strictly positive.   I have been trying to do this for awhile but I can't seem to get it. Here is my thought process: If the function is Riemann integrable, then its set of discontinuities has measure zero (Lebesgue). I am not sure how to connect this to the integral being positive Looking for a post-apocalyptic trilogy where pilot is nursed back to health by natives of the land I read a series of books around 2005. I think it might have been a trilogy.  Basic story line is in a post apocalyptic world. The main character is a pilot for the Federation or something similar to that. He crash lands, is nursed back to health by the natives, comes to like and respect them, and does not want to fight against them.  Also in the later book I think it also involves another race who are very Japanese-ish. They drink sake and the "clan" names are things like Fu-Jitsu and Mitsu-Bishi. How do I show a function on 2-adic units is continuous (using the 2-adic metric)?   I'd be happy to learn the general rule or definition. But in particular I need to show that $f(x)=\dfrac{3x+1}{2^{v_2(3x+1)}}$ is continuous at all odd numbers.  Since the function is isometric in $\lvert\cdot\rvert_2$, i.e. since $\lvert f(x)\rvert_2=\lvert x\rvert_2$ every orbit of the function is duplicated, multiplied by any power of $2$.  This can therefore be formulated in various ways; as a function though the odd numbers, through the dyadic rationals, but the following seems good to work with.  If we let $n$ be a positive integer and $k$ be the power of $2$ we can define:  $f(2^k(2n+1))=(3(2n+1)+1)\cdot2^k\cdot\lvert3(2n+1)+1\rvert_2$  So $f(2^k(2n+1)=(3n+2)\times2^k\times\lvert3n+2\rvert_2$  Here is what I have so far:  I think to prove continuity in the 2-adic metric I need $\lvert x_n-x\rvert_2=0\implies\lvert f(x_n)-f(x)\rvert_2=0$  I think $k$ and $n$ are independent so I think I can examine them independently.  Taking $k$ to infinity brings both $x$ and $f(x)$ to zero so that seems to satisfies the continuity requirement.  Moving on to $n$; this seems to be an exercise in proving convergence within odd integers which are in a sense a subset of the 2-adic units.  I know all Cauchy sequences in these converge to 2-adic units but not much more than that.  However I do have a little insight into this particular function.  For example if we examine the inputs $x$ which map to any given output of $f(x)$, it can fairly easily be shown that these $x$'s take the form of a set $\left\{4^mp+\dfrac{4^m-1}{3}:m,n\in\mathbb{N}\right\}$ so, at least for any given output $f(x)$ the inputs always converge to $x=\frac{-1}{3}$ as the intervals between them become large powers of $2$.  In fact the orbit of the function $a(2^kx)=2^k(4x+1)$ on variation of $x$ and holding $k$ fixed is in a sense orthogonal to $f(x)$; which is a restatement of the above except not in closed form. Show that $\left| \frac{1}{x}-\frac{1}{z} \right| \le \left|\frac{1}{x} - \frac{1}{y} \right| + \left|\frac{1}{y} - \frac{1}{z} \right|$. I'm trying to prove that  $$ \left| \frac{1}{x}-\frac{1}{y} \right| $$  is a metric on $X = \mathbb R^+$.  The properties of non-negativity and symmetry are obvious (do I actually even need to prove them?), but the tricky one is, as usual the inequality property, i.e.  $$ d(x,z) \le d(x,y) + d(y,z) \text{ for any } z \in X. $$  So, ok, I have that  $$ d(x,z) \le d(x,y) + d(y,z) \\ \iff \left| \frac{1}{x}-\frac{1}{z} \right| \le \left|\frac{1}{x} - \frac{1}{y} \right| + \left|\frac{1}{y} - \frac{1}{z} \right| \\ \iff \left| \frac{1}{x} \right|- \left| \frac{1}{z} \right| \le \left| \frac{1}{x}-\frac{1}{z} \right| \le \left|\frac{1}{x} - \frac{1}{y} \right| + \left|\frac{1}{y} - \frac{1}{z} \right| $$  ...and that's about as far as I've gotten–which is to say, not very far. I also tried multiplying both sides by $ \left| \frac{1}{x}-\frac{1}{z} \right| $, but that wasn't very fruitful. If someone could point me in the right direction, it'd be greatly appreciated. Thanks. Does walking fast prevent eggs hatching? I don't understand this and I'm now worried as I have donated to a lot of servers and I don't want to lose this account. On the launcher it says my new username but when I log on it says "Account not Authenticated with minecraft.net" and "Non-Valid Username".  How can I regain the ability to use my account online? I have seen lots of UI designer nowadays including this kind of illustration i want to know the name of this style so that i can also learn and try this in my designs. When and where do I have the highest chance of seeing auroras? I'm wondering what time of year is best, and what locations might be best, for catching the aurora.  I'm currently thinking of February up at Sweden's ice hotel, but since the whole point of the trip is so that my wife can see the Aurora, I want to pick a location that affords the best chances to see one.  Edit: Just adding a link so you can see realtime aurora activity in the northern hemisphere    I know this is anecdotal, but I ended up going to Iceland in late february during the new moon and saw the aurora 3 out of 6 nights I was there.  There was activity every single night but the biggest problem was weather.  It was cloudy almost every single night. Sending 2D arrays in Fortran with MPI_Gather How to Deserialize XML document How do I Deserialize this XML document:  &lt;?xml version="1.0" encoding="utf-8"?&gt; &lt;Cars&gt;   &lt;Car&gt;     &lt;StockNumber&gt;1020&lt;/StockNumber&gt;     &lt;Make&gt;Nissan&lt;/Make&gt;     &lt;Model&gt;Sentra&lt;/Model&gt;   &lt;/Car&gt;   &lt;Car&gt;     &lt;StockNumber&gt;1010&lt;/StockNumber&gt;     &lt;Make&gt;Toyota&lt;/Make&gt;     &lt;Model&gt;Corolla&lt;/Model&gt;   &lt;/Car&gt;   &lt;Car&gt;     &lt;StockNumber&gt;1111&lt;/StockNumber&gt;     &lt;Make&gt;Honda&lt;/Make&gt;     &lt;Model&gt;Accord&lt;/Model&gt;   &lt;/Car&gt; &lt;/Cars&gt;   I have this:  [Serializable()] public class Car {     [System.Xml.Serialization.XmlElementAttribute("StockNumber")]     public string StockNumber{ get; set; }      [System.Xml.Serialization.XmlElementAttribute("Make")]     public string Make{ get; set; }      [System.Xml.Serialization.XmlElementAttribute("Model")]     public string Model{ get; set; } }   .  [System.Xml.Serialization.XmlRootAttribute("Cars", Namespace = "", IsNullable = false)] public class Cars {     [XmlArrayItem(typeof(Car))]     public Car[] Car { get; set; }  }   .  public class CarSerializer {     public Cars Deserialize()     {         Cars[] cars = null;         string path = HttpContext.Current.ApplicationInstance.Server.MapPath("~/App_Data/") + "cars.xml";          XmlSerializer serializer = new XmlSerializer(typeof(Cars[]));          StreamReader reader = new StreamReader(path);         reader.ReadToEnd();         cars = (Cars[])serializer.Deserialize(reader);         reader.Close();          return cars;     } }   that don't seem to work :-( How to prove that $p-1$ is squarefree infinitely often, where $p$ is prime?  I had thought of using Dirichlet's theorem on arithmetic progressions.  The number of squareful values of $p-1$ less than or equal to $n$ is bounded by $\sum_{q}{\pi_{q^2,1}(n)}$, each term $\pi_{q^2,1}(n) \approx \frac{\pi(n)}{q \cdot (q-1)}$, and $\sum_{q}{\frac{1}{q \cdot (q-1)}} \lt 1$.  But using for example , the possibility is open that the error in each approximation for $\pi_{q^2,1}(n)$ may continue to increase with $q$, and since the sum runs up to $\sqrt{n}$, this argument is invalid.  Is there a more refined version of Dirichlet's theorem that can be used to circumvent this issue?  Or an entirely different way to prove this statement? What are the rules for calling the base class constructor? Is there an GUI Designer for python? Is there a GUI IDE for programming python just like java has netbeans?  I wanted one where we could drag &amp; drop test boxes &amp; labels just as we do in swing components using netbeans or eclipse.  Or is there an add-on present in either netbeans or eclipse itself? Git keeps prompting me for a password Is this a dismissal by hit wicket? Consider the following situation,     A batsman's bat breaks while hitting the ball after which a piece of the   bat flies in the air, hits the stumps and the bails fall down.   Is this a dismissal by hit wicket? I'm trying to create a pmatrix whose components are rather complicated fractions (Christoffel symbols), and the line spacing is too small making the whole thing a bit cramped and hard to read.  Is there any easy way to increase the spacing (about 1.5 the default would be perfect)? Where is the icon used in this dialogue box? Where on my disk can I find the icon used in this dialogue box in OS X？    It may be Security.icns in OS X 10.7.3    I cannot find it in:   /System/Library/CoreServices/CoreTypes/Contents/Resources There are only LockedIcon.icns and UnlockedIcon.icns in this folder who looks like the icon in the dialogue box,the size of the icon in the dialogue box is 128x128px, but LockedIcon.icns and UnlockedIcon.icns is 32x32px.   lockedIcon.icns    So they are not the same icon.   /System/Library/CoreServices/Finder.app/Contents/Resources/ /System/Library/CoreServices/Problem Reporter.app/Contents/Resources /Applications/System Preferences.app/Contents/Resources /Applications/Utilities/Keychain Access.app/Contents/Resources /System/Library/CoreServices/Certificate Assistant.app/Contents/Resources/