Cannot install VLC in Ubuntu 18.04.4 LTS
Unable to correct problems, you have held broken packages
Why is the observable universe so big? The observable universe is approximately 13.7 billion years old. But yet it is 80 billion light years across. Isn't this a contradiction? How do I reverse a list using recursion in Python? What Does it Really Mean to Have Different Kinds of Infinities? Can someone explain to me how there can be different kinds of infinities?  I was reading "" by  and came across the concept of countable and uncountable infinities, but they're only words to me.  Any help would be appreciated. Full Name Requirement of Commit Phase The Commitment form on Area 51 requires your full name to be provided. Is this publicly viewable? Why not just use the existing usernames? Geoserver ecw plugin problem I am trying to publish some ecw files with geoserver 2.7.2 on ubuntu 15.04 x64. I downloaded gdal plugin, gdal_data and native libraries for image-io 1.1.11 and set environment variables; GDAL_DATA, LD_LIBRARY_PATH.  I can see new store types when adding new one (ECW, EHdr, JP2ECW etc.). But when I try to save an ECW store with a valid ecw file which I tested with ArcMap, geoserver crashes with this error:    terminate called after throwing an instance of 'std::length_error'   what():  basic_string::_S_create Aborted (core dumped)  Do you have any idea about this problem? What is a word that could define someone who likes to cause conflict? When I press the power button a dialog opens, but I want to shutdown the system without receiving "Do you really really want to shutdown?". How can I choose a direct shutdown action on a pressed power button?   I had the same problem with the 11.04 version, but I don't remember the solution and yesterday I upgraded to Ubuntu 11.10. Duplicate:    I want an pseudo random number generator that can generate numbers with no repeats in a random order. For example: random(10) might return 5, 9, 1, 4, 2, 8, 3, 7, 6, 10 Is there a better way to do it other than making the range of numbers and shuffling them about, or checking the generated list for repeats?  Edit: Also I want it to be efficient in generating big numbers without the entire range.  Edit: I see everyone suggesting shuffle algorithms. But if I want to generate large random number (1024 byte+) then that method would take alot more memory than if I just used a regular RNG and inserted into a Set until it was a specified length, right? Is there no better mathematical algorithm for this. How do I show that $X = \left\{ (x,y) \in \mathbb{R}^2 \mid x \in \mathbb{Q}\text{ or }y \in \mathbb{Q}\right\}$ is path connected?    Note that $X$ is a topological space with subspace topology $\tau = \left\{ U \cap X \mid U\text{ is open in }\mathbb{R}^2\right\}$.  I only know two things (with respect to path connectedness):   A topological space $X$ is path connected iff for every $p,q \in X$, there is a continuous function $f: [a,b] \to X$ with $f(a)=p$ and $f(b) = q$.    Continuity $f$ is defined as for every open set in $X$, its preimage is open in $[a,b]$ (with subspace topology induced by $\mathbb{R}$ (with standard topology) )   Suppose $X$ and $Y$ are two topological spaces and $f: X \to Y$ is a continuous surjection. If $X$ is path connected, then $Y$ is path connected. How do I install the Intel Graphics driver in my system? Can someone help me out and explain or point me in the right direction on how to check video drivers and see if my video card running okay?  I had 10.04 installed on my Thinkpad r61 with Compiz Manager and life was great, until the machine took water damage. I bought an ASUS (X54H) since and am trying out 12.04, but the desktop just doesn't look right.  I always struggled with video driver installation. There are no proprietary drivers available in the hardware manager.  When I run lspci | grep VGA:  00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)   I will greatly appreciate your help. I want to use Linux more, but like I said video drivers appear to be my biggest concern. I have also tried 12.04 on my desktop PC, but again failed to configure video card, so switched back to Windows 7. I have $a,b,c\in\mathbb{Q}$ not all zero. ($a^2+b^2+c^2\ne 0$), I want to show that the following determinant is then non-zero. I failed to arrive at an appropriate form of the polynomial. Help please. $$\left|\begin{bmatrix} a &amp; 2c &amp; 2b\\b &amp; a &amp; 2c\\ c &amp; b &amp; a\end{bmatrix}\right| = a^3+2 b^3-6 a b c+4 c^3$$    Second question, what is the easiest way to argue that $\{1,\sqrt[3]{2},(\sqrt[3]{2})^2\}$ is linearly independent in $\mathbb{Q}$?    Motivation: Prove that $\mathbb{Q}[\sqrt[3]{2}] = \{a+b\sqrt[3]{2}+c(\sqrt[3]{2})^2\;|\;a,b,c\in\mathbb{Q}\}$ forms a field.   Proof: Since $\mathbb{Q}[\sqrt[3]{2}] \subset \mathbb{R}$, we prove $\mathbb{Q}[\sqrt[3]{2}]$ is a subfield of $(\mathbb{R},+,\cdot)$    $\forall (a+b\sqrt[3]{2}+c(\sqrt[3]{2})^2)\in \mathbb{Q}[\sqrt[3]{2}]\backslash\{0\}.$ We want to find $(a+b\sqrt[3]{2}+c(\sqrt[3]{2})^2)$ such that    $(a+b\sqrt[3]{2}+c(\sqrt[3]{2})^2)(d+e\sqrt[3]{2}+f(\sqrt[3]{2})^2) =$ $ (ad+2ec+2bf)+(ae+bd+2cf)\sqrt[3]{2}+(af+cd+be)(\sqrt[3]{2})^2 = 1$    Since $\{1,\sqrt[3]{2},(\sqrt[3]{2})^2\}$ is linearly independent (?) over $\mathbb{Q}$, we show there is unique solution to: $$\begin{bmatrix} a &amp; 2c &amp; 2b\\b &amp; a &amp; 2c\\ c &amp; b &amp; a\end{bmatrix} \cdot \left[\begin{array}{l l} d\\e\\f \end{array}\right] = \left[\begin{array}{l l} 1\\0\\0 \end{array}\right] $$ Which is equivalent in showing the determinant is non-zero $$\left|\begin{bmatrix} a &amp; 2c &amp; 2b\\b &amp; a &amp; 2c\\ c &amp; b &amp; a\end{bmatrix}\right| = a^3+2 b^3-6 a b c+4 c^3=(?)$$    By subfield test, 1)2)3)4) is enough to say that $(\mathbb{Q}[\sqrt[3]{2}],+,\cdot)$ is a subfield of $(\mathbb{R},+,\cdot)$ therefore a field.  EDIT: If you have shorter way that prove the proposition without touching my 2 questions, that is even better. Windows Metro apps have wrong icon in search UI How many keys does the Playfair Cipher have? What do I need to consider to choose between dSLR, mirrorless, or a compact as my first "serious" camera? I am thinking of buying a camera to learn photography. Most of the time I'll be shooting portraits and landscapes. But I am not sure where I should start. Most of my friends tell me that I should get an entry level DSLR, but I am not sure if I have the persistence and enthusiasm to carry it all day in a backpack. But the camera on my cellphone doesn't seem to be enough to begin with.  So what I want is some expert advice (preferably with professional experience). Can most compact fixed-lens or mirrorless cameras fit the situations I mentioned? Or do I really need to go to a DSLR to get a tool to learn photography? We have been using Notes and Attachment to store files related to the record. I also read about Files in salesforce.   How are Files different from Attachment? Are there any limitations or benefits of using Files instead of Attachments?  Are Files available for all editions of Salesforce?  Is it possible to link Files to particular records so they are visible as related list? I tried looking into the content version  but cant seem to find anything to relate to a record I don't know how to prove this example. Let $y(t):\mathbb{R}^+\to \mathbb{R}$ be a nonincreasing function. Assume that there is a constant $A&gt;0$ such that \begin{equation} \int_{s}^{+\infty}y(t)dt \leq Ay(s), \quad 0\leq s&lt;+\infty \end{equation} Then $y(t)\leq y(0)e^{1-\frac{t}{A}}$, for all $t&gt;0$. Django template how to look up a dictionary value with a variable "May I have a glass of water" vs. "Can I have a glass of water": which is better, "may I" or "can I", when asking for something? What is the correct sentence when asking for something like while flying asking for a glass of water :     May I have a glass of water     or      Can I have a glass of water Hyperref "enquotes" metadata EDIT: As Bill B. and Caramdir point out in their comments after Bill B. produced his results posted below, more information is needed in order to make a better call. To remedy, my output was produced using MiKTeX 2.8 pdflatex with no special command line flags or switches. My pdf viewer is Adobe Acrobat Pro 9.0. The platform is Windows 7. All software including hyperref is fully up to date against the latest rev levels and patches.  As I'm guessing that this is a pretty normal setup, at least in the Windows world, I'd be very interested (and grateful) in learning whether this problem affects other people or whether it's just some kind of rather weird one-off. My gut feel after seeing Bill B's results (and also after having traversed hyperref's code) is that the culprit is Adobe Acrobat or possibly MiKTeX pdflatex.    Can anyone corroborate? I'd be very grateful to know.    Original question:  I have a problem with hyperref; it "enquotes" Author and Keywords (but not Title or Subject) metadata if the data sent to these contain a comma or semi-colon (but not, say, a full stop or a colon).    I've included some figures and code that show this below.         \documentclass{article}  \newcommand*\metadata{% % uncomment all but one line below %  a  b  c%     &lt;-- no problem    a, b, c%     &lt;-- problem %  a; b; c%     &lt;-- problem %  a: b: c%     &lt;-- no problem %  a* b* c%     &lt;-- no problem }  \usepackage[   pdftitle={\metadata},    % never enquoted   pdfauthor={\metadata},   % enquoted if , or ; is present   pdfsubject={\metadata},  % never enquoted   pdfkeywords={\metadata}, % enquoted if , or ; is present ]{hyperref}  \begin{document}   Press ctl-d (in Acrobat Reader) to see pdf file metadata. \end{document}   Not only is this quite ugly but, more importantly, it interferes with metadata extracting programs used by certain document repositories.   I've worked my way through hyperref's code without much success. Would anyone have a solution for this problem?  Or advice about what I might be doing wrong? I need a number of different full-page DOM samples for my qUnit test suite