Does apt on 20.10 have a virtualbox package? I see that apt install virtualbox virtualbox-dkms has worked on previous releases but on 20.10  apt install virtualbox   Reading package lists... Done  Building dependency tree         Reading state information... Done  Package virtualbox is not available, but is referred to by another package.  This may mean that the package is missing, has been obsoleted, or  is only available from another source   E: Package 'virtualbox' has no installation candidate  apt search doesn't find anything like it.
I keep seeing places refer to the "multiverse" repository as a place I can get software, how can I enable this repository? Please specify how to do this graphically and via command line.
I'm trying to create a functioning sub theme of Omega 4.4. I've worked  with Drush before with it, but the site is on a host that I'm not administrator of. I've tried the  but not succeeded in executing the Omega Wizard. In short, the Omega Wizard may be extremely helpful, but I can't get it to work.   Next, I've tried to manually create a sub theme using the . However, the results of this is a theme catalogue in the Themes-folder, but the theme not showing up in Drupal. Perhaps I'm using the wrong instructions for the wrong version of Omega?  Anyhow, does anyone have instructions for how to install an Omega 4.4 sub theme manually for Drupal 7? Sorry for the bad English. I'm trying to use the tikz-cd package to make commutative diagrams. My code  \documentclass{article} \usepackage[brazil]{babel} \usepackage{tikz-cd} \begin{document} \begin{tikzcd} A \ar[r, "x"] &amp; B \end{tikzcd} \end{document}    The problem occurs when putting a name under the arrow, the syntax "x" is incompatible with the brazil option of the babel package. When exchanging brazil for english it works normally. I already tried using  \usepackage[main=brazil, english]{babel}, \usepackage[brazil, english]{babel} e  \usepackage[brazil, main=english]{babel}   But it did not work. I also tried to use  \usepackage[english, brazil]{babel} \usepackage{polyglossia} \setmainlanguage{brazil} \setotherlanguages{english}   And finally  \selectlanguage{english}   However, it only works if I remove the option brazil Why are naturals < modulus equal if congruent? [uniqueness of remainder] Let $a$, $b$, and $n$ be integers with $0 \le a \lt n$ and $0 \le b \lt n$. Suppose $a \equiv b \pmod n$. Then $a-b=0$ and $a=b$. Why does the congruence of two non negative integers imply that they must be equal? Is the expression "yesterday afternoon" correct? Is it proper to use the following expressions  I started to London yesterday afternoon . I started to London yesterday morning  I ask because it is supposedly correct to say 'last night'. Why don't we say 'last afternoon' or 'last morning'? Corrupt Backupt GPT Table I am having trouble with the following problem.      Let $R$ be an integral domain, and let $a \in R$ be a non-zero element. Let $D = \{1, a, a^2, ...\}$. I need to show that $R_D \cong R[x]/(ax-1)$.    I just want a hint.  Basically, I've been looking for a surjective homomorphism from $R[x]$ to $R_D$, but everything I've tried has failed. I think the fact that $f(a)$ is a unit, where $f$ is our mapping, is relevant, but I'm not sure. Thanks Possible Duplicate:          The square root of a number squared is equal to the absolute value of that number. Why is $\sqrt{x^2} = |x|$? Why not just $x$? Please give me a reason and also help me prove it. Radio antenna producing waves in the visible spectrum If a radio could produce waves in the visible light spectrum, what would the result be?  This is a thought experiment that I've pondered for a few years now.  I realize there are a few/many real-world constraints, but if we lifted these constraints for the sake of thought, what could we expect?  Personally, I don't see why we wouldn't observe visible light emitting from the antenna, disregarding any light from Blackbody Radiation. Automatically login and lock I want to configure Windows 7 to login automatically after the computer is switched on. That's not because I'm lazy and don't like typing passwords. That's because I want programs that are configured to run on startup run automatically.  But I don't want everyone to see my desktop, so I want my computer to remain locked. When I'm ready to work, I just type my password and don't have to wait until all startup programs run. How do I interpret the Mann-Whitney U when using R's formula interface I remember being taught that the correct order of adjectives in English was something along the lines of "Opinion-Size-Age-Color-Material-Purpose."  However, it's been a long time and I'm pretty sure I've forgotten a few categories (I think there were eight or nine). Can anyone fill them in? I want to color sketches in Photoshop, but when I prepared the sketch (using Levels, Hue, and other modifications) to turn it into workable line art, some details were missing. I think it depends on how you draw your sketch.  What are important steps for drawing a sketch (with pen or pencil) that is to be colored in Photoshop? A step-by-step instruction would be appreciated.  For instance, here it is the sketch    This is after my preparations in Photoshop Best way to follow a log and execute a command when some text appears in the log Suppose we have a magnetic field directed into the computer screen. Assume that there is no gravitational field. Now suppose we have a stationary positively charged particle in the magnetic field. The magnetic force is given by $$\mathbf{F}=q\mathbf{v}\times\mathbf{B}$$  Since $\mathbf{v}=0, \mathbf{F}=0$.  Now pick a reference frame moving to the left with constant velocity. In this frame, the particle is moving to the right with constant velocity. So, the magnetic force is directed upwards.  From what I've learnt in physics, forces are independent of choice of reference frames as long as the frames are inertial. But in the 2 inertial reference frames I have chosen, I get 2 different magnetic forces. How do we reconcile this? Can X.org Load Two Different Drivers? (Triple-Head Setup with Intel and NVidia Card) We want to set up a 3 screens with an onboard intel graphics adapter and an nvidia card.  Both cards are recognized in lspci   01:00.0 VGA compatible controller: NVIDIA Corporation GT218 [GeForce 210] (rev a2) 00:02.0 Display controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)   And bascially work: If I switch to the console, I see output on the Intel card, X is only running on the Nvidia card.  But when I type xrandr | grep conn I get only one connected port:   DVI-I-0 disconnected (normal left inverted right x axis y axis) VGA-0 disconnected (normal left inverted right x axis y axis) DVI-I-1 connected 1920x1200+0+0 (normal left inverted right x axis y axis) 518mm x 324mm HDMI-0 disconnected (normal left inverted right x axis y axis)   I am on Ubuntu 12.10 (and XFCE) and installed the proprietary nvidia driver.  I was assuming that X maybe has a problem to autodetect both cards, so I thought the following xorg.conf could help:   Section "ServerLayout"     Identifier     "Layout0"     Screen      0  "Screen0"     Screen      1  "Screen1"     InputDevice    "Keyboard0" "CoreKeyboard"     InputDevice    "Mouse0" "CorePointer" EndSection  Section "Files" EndSection  Section "InputDevice"     # generated from default     Identifier     "Mouse0"     Driver         "mouse"     Option         "Protocol" "auto"     Option         "Device" "/dev/psaux"     Option         "Emulate3Buttons" "no"     Option         "ZAxisMapping" "4 5" EndSection  Section "InputDevice"     # generated from default     Identifier     "Keyboard0"     Driver         "kbd" EndSection  Section "Monitor"     Identifier     "Monitor0"     VendorName     "Unknown"     ModelName      "Unknown"     HorizSync       28.0 - 33.0     VertRefresh     43.0 - 72.0     Option         "DPMS" EndSection  Section "Device"     Identifier     "Device0"     Driver         "nvidia"     VendorName     "NVIDIA Corporation"     BoardName      "GeForce 210" EndSection  Section "Screen"     Identifier     "Screen0"     Device         "Device0"     Monitor        "Monitor0"     DefaultDepth    24     SubSection     "Display"         Depth       24     EndSubSection EndSection   Section "Monitor"     Identifier     "Monitor1"     VendorName     "Unknown"     ModelName      "Unknown"     HorizSync       28.0 - 33.0     VertRefresh     43.0 - 72.0     Option         "DPMS" EndSection  Section "Device"     Identifier     "Device1"     Driver         "intel"     VendorName     "Intel"     BoardName      "Internal Intel Graphics" EndSection  Section "Screen"     Identifier     "Screen1"     Device         "Device1"     Monitor        "Monitor1"     DefaultDepth    24     SubSection     "Display"         Depth       24     EndSubSection EndSection   But it is still not working.   Is this generally possible to use two different drivers in X ? Is it necessary to create an xorg.conf manually then? (because Ubuntu 12.10 normally works without the xorg.conf) Are there any errors in my xorg.conf? When and why is the [featured] tag removed by the Community user? I've found that the Meta (moderator only) tag  is automatically  by the  user. So, I want to know when and why is the tag  is removed by this user?  Is there any mechanism for this removal or is there simply a specified time period after which the  is automatically removed by the Community user? Subdividing Causes Strange Edges / Issues on Shape Show (within ZF Set Theory without choice) that for any sets $A,B,C:$   If $|A|^{|B|} = |B|$, then $|A| = 1 = |B|.$   That is, if there is a bijection from $|A|^{|B|}$ to $|B|$, then  $|A| = 1 = |B|.$  Please help me.. How do we know the brain flips images projected on the retina back around? Why do we turn images upside down again rather than dealing with them directly, still vertically rotated after passing through our lens?   I don't see how that would cause any problems, and how we'd ever be able to figure out if we are presented with flipped images after getting used to interacting based on visual input, whether flipped or not.   What am I missing? Holomorphic self map on the open unit disc