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Filesystem shows /dev/nvme0n1p1 instead of /dev/sda I installed a dual boot of Ubuntu 16.04 (Windows being my other OS) two months ago to try it out. I want to allot more space to it on my hard drive. I was looking up tutorials, and I noticed that my filesystem names don't look anything like those in the tutorials. For example:  df -h   outputs:    How would I allot more space to Ubuntu (in layman's terms)? I understand that the  is given by  $$F^{\mu\nu}\mapsto\begin{pmatrix}0 &amp; -E_{x} &amp; -E_{y} &amp; -E_{z}\\ E_{x} &amp; 0 &amp; -B_{z} &amp; B_{y}\\ E_{y} &amp; B_{z} &amp; 0 &amp; -B_{x}\\ E_{z} &amp; -B_{y} &amp; B_{x} &amp; 0 \end{pmatrix}$$  where $\mu$, $\nu$ can take the values {0,1,2,3} or {$t,x,y,z$}.  So, for example  $$F^{01}=F^{tx}=-E_x$$  My question is, what would the following expression be?  $$F^{t\rho}=?$$ or $$F^{z\rho}=?$$  where $\rho=\sqrt{x^{2}+y^{2}}$ is the radial coordinate in ?  And more generally, how can we construct the Electromagnetic Tensor in cylindrical coordinates? Where $\mu$, $\nu$ now take the values {$t,\rho,\varphi,z$}. Event binding on dynamically created elements? Hamiltonian Cycle Problem At the moment I'm trying to prove the statement:     $K_n$ is an edge disjoint union of Hamiltonian cycles when $n$ is odd.   ($K_n$ is the complete graph with $n$ vertices)  So far, I think I've come up with a proof. We know the total number of edges in $K_n$ is $n(n-1)/2$ (or $n \choose 2$) and we can split our graph into individual Hamiltonian cycles of degree 2.   We also know that for n vertices all having degree 2, there must consequently be $n$ edges. Thus we write $n(n-1)/2 = n + n + ... n$ (here I'm just splitting $K_n$'s edges into some number of distinct Hamiltonian paths) and the deduction that $n$ must be odd follows easily.  However, the assumption I made - that we can always split $K_n$ into Hamiltonian paths of degree 2 if $K_n$ can be written as a disjoint union described above - I'm having trouble proving. I've only relied on trying different values for $n$ trials and it hasn't faltered yet. So, I'm asking:     If it is true, how do you prove that if $K_n$ can be split into distinct Hamiltonian cycles, it can be split in such a way that each Hamiltonian cycle is of degree 2? Under what conditions is $AA^T$ invertible? Given a matrix $A$ with dimensions $m \times n$, is $B=AA^T$ invertible if and only if the rows of $A$ are linearly independent?  So far, I've tried writing A as row vectors,   $$A = \begin{bmatrix}v_1\\ v_2\\ \vdots \\ v_m\end{bmatrix}$$  where $B_{i,j} = (v_i v_j) $  The Wikipedia page on the  suggests that the condition I stated above is necessary and sufficient, but does not provide a proof. You have already activated X, but your Gemfile requires Y I encountered this particular combinatorial identity :$$\begin{align}&amp;1\dbinom{n-1}{r-1}+2\dbinom{n-2}{r-1}+\cdots+(n+1-r)\dbinom{r-1}{r-1}\\=&amp;\dbinom{n}{r}+\dbinom{n-1}{r}+\cdots+\dbinom{r}{r}\\=&amp; \dbinom{n+1}{r+1}\end{align}$$How does one figure it out? Generalized Pell equation $x^2-2y^2=49$ How to change an input button image using CSS So, I can create an input button with an image using &lt;INPUT type=&quot;image&quot; src=&quot;/images/Btn.PNG&quot; value=&quot;&quot;&gt;  But, I can't get the same behavior using CSS. For instance, I've tried &lt;INPUT type=&quot;image&quot; class=&quot;myButton&quot; value=&quot;&quot;&gt;  where &quot;myButton&quot; is defined in the CSS file as .myButton {     background:url(/images/Btn.PNG) no-repeat;     cursor:pointer;     width: 200px;     height: 100px;     border: none; }  If that's all I wanted to do, I could use the original style, but I want to change the button's appearance on hover (using a myButton:hover class). I know the links are good, because I've been able to load them for a background image for other parts of the page (just as a check). I found examples on the web of how to do it using JavaScript, but I'm looking for a CSS solution. I'm using Firefox 3.0.3 if that makes a difference. How to read contacts on Android 2.0 In Harry Potter, what kind of home life do those born to a wizard and a Muggle have? A single word or phrase for something that necessarily causes both harm and benefit? What is a single word, or phrase, for something that necessarily causes both harm and benefit? For example, a coal-fired power plant will harm human health through air pollution, but will bring electricity and economic development to a poor area. OpenLayers low resolution and/or shifts in QGIS print composer? I'm having trouble with the OpenLayers Plugin of Qgis and the map composer:  If I create an OSM-background layer and if I want to export this, the OSM-Layer looks perfectly all right in the normal qgis program window. But in the map composer and after export the layer has shifted relatively to my other shape layers (EPSG:32633 - WGS 84 / UTM zone 33N).  The second thing is that the output resolution of the exported osm-layer is very, very poor.   A really bad way of getting around this whole trouble would be to increase the screen resolution and make a screenshot of the map composition window of qgis. But I don't think this would be very professional. It also would cause a lot of pain :)   I'm using Qgis 1.8.0-Lisboa under Linux. The openlayers plugin is version 0.92. executing Python script in PHP and exchanging data between the two Could Dark Matter form black hole? Some people speculate that the mysterious dark matter in the universe could be tiny black holes. But on the other side, could dark matter particles attract each other by gravity and finally form a black hole? Since dark matter is even more abundant than normal matter, the dark matter black hole should not be rare. We currently have two rewards checking accounts.  We are nearing the maximums permitted on each account, after which we receive .5% and .25% APY.  It's within our means to perhaps open another one, but at that point we are looking at using our debit cards 50 to 55 times a month.  I feel that running that number of debit transactions is getting out of hands as it's just the two of us.  I realize there are easy ways to game the system, but I want these things to stay around and another person doing just such that could lead to the ends of these accounts.  We are saving towards a new house down payment.  As such we don't require these funds to be fully liquid, but would still like to remain free of as much risk as possible -- however I realize we are unlikely to find anything near our rewards checking accounts (4% APY interest for meeting various rules: direct deposit, a certain number of debit card transactions, and not receiving a paper statement), but would hope we can get at least half of that.  We aren't fully sure when we will be buying, but we are probably a couple of years out.  For that reason I don't think CDs would work.  Even if we ladder them, when we need the money we will need it pretty much instantly.  Do I bite the bullet and just find the best available money market account?  What other options do I have that let me deposit monthly, and not have a timebomb associated to accessing that money that isn't in the initial lump sum? Spaces in files names in \input or \includegraphics I'm going crazy...  I have a file I want to include which path is C:\Users\Matthieu\Documents\Folder withOneSpace\myFile.tex. (As you can see with the \, I'm on windows actually)  I tried the following but none works:  \input{C:/Users/Matthieu/Documents/Folder withOneSpace/myFile} \input{C:/Users/Matthieu/Documents/Folder\ withOneSpace/myFile} \input{C:/Users/Matthieu/Documents/Folder withOneSpace/myFile.tex} \input{C:/Users/Matthieu/Documents/Folder\ withOneSpace/myFile.tex}   I also tried to put the file out of the folder with a space and it works (no surprise):  \input{C:/Users/Matthieu/Documents/myFile} --&gt; Works   All I found is to put a \ before the space but it doesn't work at all. --> Please help ! :) What is the exact use of the symbols $\partial$, $\delta$ and $\mathrm{d}$ in derivatives in physics? How are they different and when are they used? It would be nice to get that settled once and for all.  $$\frac{\partial y}{\partial x}, \frac{\delta y}{\delta x}, \frac{\mathrm{d} y}{\mathrm{d} x}$$   For what I know, $\mathrm{d}$ is used as a small infinitisemal change (and I guess the straight-up letter $\mathrm{d}$ is usual notation instead of italic $d$, simply to tell the difference from a variable). Of course we also have the big delta $\Delta$ to describe a finite (non-negligible) difference. And I have some vague idea that $\partial$ is used for partial derivatives in case of e.g. three-dimensional variables. Same goes for $\delta$, which I would have sworn was the same as $\partial$ until reading this answer on Math.SE:    Then to make the confusion total I noticed an equation like $\delta Q=\mathrm{d}U+\delta W$ and read in a physics text book that:     The fact that the amount of heat [added between two states] is dependent on the path is indicated by the symbol $\delta$...   So it seems $\delta$ means something more? The text book continues and says that:     a function [like the change in internal energy] is called a state function and its change is indicated by the symbol $\mathrm{d}$...   Here I am unsure of exactly why a $\mathrm d$ refers to a state function.   So to sum it up: down to the bone of it, what is $\delta$, $\partial$ and $\mathrm{d}$ exactly, when we are talking derivatives in physics.  Addition  Especially when reading a mathematical process on a physical equation like this procedure:  $$\delta Q=\mathrm{d}U+p\mathrm{d}V \Rightarrow\\ Q=\Delta U+\int_1^2 p \mathrm{d}V$$  It appears that $\delta$ and $\mathrm{d}$ are the same thing. An integral operation handles it the same way apparently? How does the Performance Index work? In one of Dota2's recent patches, Valve has added a new feature called "Performance Index" visible in your own in-game profile.  It is not clear how it works. Is there any information available, what "performance" it monitors?  Does it rely on K/D, K/D/A, Gold per minutes, Experience per minute, or all of them? C# 3.0 auto-properties — useful or not? Note: This was posted when I was starting out C#. With 2014 knowledge, I can truly say that auto-properties are among the best things that ever happened to the C# language.  I am used to create my properties in C# using a private and a public field:  private string title; public string Title {     get { return title;  }     set { title = value;  } }   Now, with  3.0, we got auto-properties:  public string Title { get; set; }   I know this is more a philosophical/subjective questions, but is there any reason to use these auto-properties except from saving five lines of code for each field? My personal gripe is that those properties are hiding stuff from me, and I am not a big fan of black magic.  In fact, the hidden private field does not even show up in the debugger, which is OK given the fact that the get/set functions do nothing. But when I want to actually implement some getter/setter logic, I have to use the private/public pair anyway.  I see the benefit that I save a lot of code (one vs six lines) without losing the ability to change the getter/setter logic later, but then again I can already do that by simply declaring a public field "Public string Title" without the need of the { get; set; } block, thus even saving more code.  So, what am I missing here? Why would anyone actually want to use auto-properties?