undefined reference to `vtable for ' namespace inheritance undefined reference to `typeinfo for
g++ undefined reference to typeinfo
I'm trying to install Anbox in my new Ubuntu 16.04 using instructions from  . It seemed to work, but I got no icon in my dash, so I suspect that the installation is not complete. With Synaptic  Package Manager I can see that anbox-common &amp; anbox-modules-dkms are installed, but I have no icon in my dash, so I tried running   sudo snap install --edge --devmode anbox   and got this error:  error: cannot install "anbox": Get    https://search.apps.ubuntu.com/api/v1/snaps/details/core?channel=stable&amp;fields=anon_download_url%2Carchitecture%2Cchannel%2Cdownload_sha3_384%2Csummary%2Cdescription%2Cdeltas%2Cbinary_filesize%2Cdownload_url%2Cepoch%2Cicon_url%2Clast_updated%2Cpackage_name%2Cprices%2Cpublisher%2Cratings_average%2Crevision%2Cscreenshot_urls%2Csnap_id%2Csupport_url%2Ccontact%2Ctitle%2Ccontent%2Cversion%2Corigin%2Cdeveloper_id%2Cprivate%2Cconfinement%2Cchannel_maps_list:    dial tcp: lookup search.apps.ubuntu.com on [::1]:53: read udp    [::1]:54255-&gt;[::1]:53: read: connection refused   What am I doing wrong? Why was the connection refused? According to the instructions, it seems this is the correct command to install it.  ps: I'm not that familiar with Linux, I'm more of a Windows guy, trying to learn Linux. \bordermatrix with brackets [ ] instead of parentheses ( ) I have the following code:  \documentclass{article} \begin{document} $ M = \bordermatrix{~ &amp; x &amp; y \cr               A &amp; 1 &amp; 0 \cr               B &amp; 0 &amp; 1 \cr} $ \end{document}   But this code makes a matrix with () and i would like it to be with [] How do i do this? What is the best file extension for an SEO friendly URL? I'm working for a website to convert the website URL to an SEO friendly URL. I plan to use this:  example.com/category-name/pageid-123-page-name  I looked at some similarly categorized, highly ranked websites. They have the same structure, except for one thing. In one case, the URL format was  example.com/category-name/pageid-123-page-name.html  Another was   example.com/category-name/pageid-123-page-name.php  Now I know the text in URLs help with SEO. Is it more helpful to have a file extension? If yes, which one is better?  Or if my current plan is okay, will it be better with a / at the end? How can I take a picture with my webcam in Windows 7? I know it existed as sort of a folder in Windows Explorer in at least Windows XP, but I just can't seem to find it in Windows 7...  How can I take a picture with my webcam in Windows 7 without using any 3rd party tools? Programmatically create a user and assign a role I'm programmatically creating a user with the following code.  $newUser = array(   'name' =&gt; $mail,    'pass' =&gt; 'password',  // note: do not md5 the password   'mail' =&gt; $mail,    'status' =&gt; 1,    'init' =&gt; $mail,   'roles' =&gt; array(5) ); $user = user_save(null, $newUser);   I have got a role with the role ID equal to 5; when I create the user, in the table "users_roles" there is only a row with the value 0 for the role ID, but if I print the user object with var_dump(), it looks like the roles are created.  What am I doing wrong? What is a primary decomposition of the ideal $I = \langle xy, x - yz \rangle$? Given the ring $k[x,y,z]$, where $k$ is a field, and an ideal $I=(xy,x-yz)$, find a primary decomposition of $I$.    I tried to draw the graph of the variety of $I$ and get a decomposition of $(x,y)\cap(x,z)$ (the two prime ideals corresponds to the irreducible components of the variety), but apparently these two ideals are not the primary decomposition of $I$, and I don't know how to fix this.  I would really appreciate it if someone can help me. thx Atiyah-Macdonald, Exercise 5.4 I was having some trouble with the following exercise from Atiyah-Macdonald.     Let $A$ be a subring of $B$ such that $B$ is integral over $A$. Let $\mathfrak{n}$ be a maximal ideal of $B$ and let $\mathfrak{m}=\mathfrak{n} \cap A$ be the corresponding maximal ideal of $A$. Is $B_{\mathfrak{n}}$ integral over $A_{\mathfrak{m}}$?   The book gives a hint which serves as a counter-example. Consider the subring $k[x^{2}-1]$ of $k[x]$ where $k$ is a field, and let $\mathfrak{n}=(x-1)$. I am trying to show that $1/(x+1)$ could not be integral over $k[x^{2}-1]_{\mathfrak{n}^{c}}$.  I have understood why this situation serves as a counterexample. But I am essentially stuck at trying to draw a contradiction. A hint or any help would be great. What formats supporting animation are suitable for the web? Who provides the Internet service to Internet Service Providers (ISPs)? I've been wondering recently about how the infrastructure of the Internet really works.    I know that I have an Internet Service Provider (ISP) that supplies my connection to the Internet.   But what I don't know is: Who provides the Internet to the ISP?  And who supplies it to them? Is there a never-ending loop that eventually connects us all together? Can an observer B move in such a way that his clock will run faster than that of a fixed observer A? My understanding of Special and General Relativity comes from books which attempt to explain them to non-experts in these fields.   Let A and B be observers, which at some time t(0), are together at some location P fixed to the earth's surface. A and B are provided with "clocks", which at time t(0), are identical lumps of the same radioactive element-that has a very long half-life. A and A's "clock" remain fixed to the earth's surface. B and B's "clock" leave A and stay together, but eventually return to A after some interval of time T (as measured by A's "clock"). If, during this time T, B's velocity relative to A is sufficiently close to the velocity of light or B remains close to a sufficiently massive body, it seems that time can "pass more slowly" for B than for A. So that when B rejoins A, B's "clock" will contain more of the radioactive element than A's "clock"   My question is: Are there any scenarios that B together with B"s "clock" can undergo (during the time T) which will cause time to "pass more quickly" for B than for A? So that when B rejoins A, B's "clock" will contain less of the radioactive element than A's "clock". If there are no such scenarios, is there any fact or law in Relativity theory which rules them out? Why do my LED lights stay on, even when the switch is off? Why do the major and minor groove exist in DNA? So I know that the major/minor groove arise from the offset pairing of the two strands in the helix.  All my textbook tells me is that "pitch causes the off-set pairing of DNA and this gives rise to the major and minor grooves."  I'm not too sure what this is saying.  What exactly is pitch and how does it give rise to the grooves? Natural number solutions to $\frac{xy}{x+y}=n$ (equivalent to $\frac 1x+\frac 1y=\frac 1n$) I have a question about the following problem from a Putnam review:  Let $n\in \mathbb{N}$. Find how many pairs of natural numbers $(x, y)\in \mathbb{N}\times \mathbb{N}$ solve $$ \frac{xy}{x+y}=n. $$  I have found some solutions for all $n$, such as $(2n, 2n)$ and $(n+1, n(n+1))$, but I feel as though this is the wrong approach, as the question is only asking for the number of solutions to the equation.  I don't really want a complete solution, but any hints would be greatly appreciated. How to compare dates in Java? What ensures big holes in my bread? Proving $\int_{0}^{\infty} \mathrm{e}^{-x^2} dx = \frac{\sqrt \pi}{2}$ For what natural numbers is $n^3 < 2^n$? Prove by induction Problem  For what natural numbers is $n^3 &lt; 2^n$?  Attempt @ Solution   For $n=1$, $1 &lt; 2$ Suppose $n^3 &lt; 2^n$ for some $n = k \ge 1$ It looks like the inequality is true for $n = 0$, $n = 1$ and $n\ge10$ But, how can I prove this through induction? Remove suggested apps option in iOS 10 Difference between Loading a class using ClassLoader and Class.forName How to change Function (Fn) Key behavior on wireless Logitech keyboard I do have a wireless Logitech K750 keyboard (silver Mac version) connected to a Lenovo ThinkPad (via the unifying USB receiver, together with a wireless Logitech mouse M705) and currently running Ubuntu 12.04.  By default the F-keys are mapped as multimedia/function keys, e.g. Play  /Pause. As I don't use them very often, I want the F-keys to behave like the "real" F-keys (F1-F12). How can I do that?  I know there is an option in the BIOS settings, but this only toggles the built-in keyboard of the notebook, not on my wireless keyboard.  I know there is a way to change this for the Apple wireless keyboard (), but there is no "parameters" directory in /sys/module/hid_logitech_dj/.  Any ideas? Or is there maybe a way to do this in a later Ubuntu version (13.04)?  UPDATE:  lsusb -d 046d: shows Bus 002 Device 005: ID 046d:c52b Logitech, Inc. Unifying Receiver  UPDATE 2: Thanks a lot for your help Lekensteyn. Finally  works just fine. In the "Known Issues" of Solaar it says that it does not work with the Nano Receiver. But I have one and it works just fine. Just don't forget to read the installation instructions and run the rules.d/install.sh script. It also recognized my M705 Mouse.