I am attempting to install Packet Tracer on my machine running Ubuntu 20.04, and I keep running into the same issue. While going through several different tutorials on installing Packet Tracer 7.2.2, I run into the same problem: I keep getting the 404 Error message when I get to the part of adding multiarch-support. The line in terminal that is causing me the errors is: wget http://archive.ubuntu.com/ubuntu/pool/main/g/glibc/multiarch-support_2.29-0ubuntu2_amd64.deb  Does anyone have any idea how to correct this? Or what am I doing incorrectly? Thanks for the help!
I am trying to install Packet Tracer 7.3 (latest version) on Ubuntu 20.04 but do not succeed to so so because of two dependencies which are not installable ("libdouble-conversion1" and "qt-at-spi").  However I successfully installed the previous version (7.2.2) which was available in an Ubuntu installer format (.run file) but I nothing happens when I run it from my gnome desktop.  I am quite a newbie in Linux so I appologies if answers are obvious...  Thanks in advance ;-)  Denis
Proving the snake lemma without a diagram chase Suppose we have two short exact sequences in an abelian category $$0 \to A \mathrel{\overset{f}{\to}} B \mathrel{\overset{g}{\to}} C \to 0 $$ $$0 \to A&#39; \mathrel{\overset{f&#39;}{\to}} B&#39; \mathrel{\overset{g&#39;}{\to}} C&#39; \to 0 $$ and morphisms $a : A \to A&#39;, b : B \to B&#39;, c : C \to C&#39;$ making the obvious diagram commute. The snake lemma states that there is then an exact sequence $$0 \to \ker a \to \ker b \to \ker c \to \operatorname{coker} a \to \operatorname{coker} b \to \operatorname{coker} c \to 0$$ where the morphisms between the kernels are induced by $f$ and $g$ while the maps between the cokernels are induced by $f&#39;$ and $g&#39;$.  It is not hard to show that the morphisms induced by $f, g, f&#39;, g&#39;$ exist, are unique, and that the sequence is exact at $\ker a, \ker b, \operatorname{coker} b, \operatorname{coker} c$. With the use of a somewhat large diagram shown , we can even construct the connecting morphism $d : \ker c \to \operatorname{coker} a$. However, I'm stuck showing exactness at $\ker c$ and $\operatorname{coker} a$. I thought Freyd might have had an element-free proof in his book, but it turns out he proves it by diagram chasing and invoking the Mitchell embedding theorem [pp. 98–99]. Is there a direct proof? How to print results in SQLcmd window Get steam to realize I have games already installed I uninstalled and re-installed steam. I didn't uninstall my games, and they still exist on my hard drive (I checked).  I have an SSD and a HDD, and to save space I install programs (including steam) to C:\Program Files (x86)\Steam drive (SSD) and games to D:\Games\SteamApps (HDD). How to I let steam know the programs are installed there? Deriving the Coulomb force equation from the idea of photon exchange? Since Newton's law of gravitation can be gotten out of Einstein's field equatons as an approximation, I was wondering whether the same applies for the electromagnetic force being the exchange of photons. Is there an equation governing the force from the exchange of photons? Are there any links which would show how the Coulomb force comes out of the equations for photon exchange? I know that my question is somewhat similar to the one posted here , but it doesn't really have an answer to my question specifically. I was surprised recently to find that it's possible to have a return statement in a finally block in Java.  It seems like lots of people think it's a bad thing to do as described in ''. Scratching a little deeper, I also found '' which shows some pretty horrible examples of other types of flow control in finally blocks.  So, my question is, can anyone give me an example where a return statement (or other flow control) in a finally block produces better / more readable code? Integral representation of Euler's constant Prove that : $$ \gamma=-\int_0^{1}\ln \ln \left ( \frac{1}{x} \right) \ \mathrm{d}x.$$  where $\gamma$ is Euler's constant ($\gamma \approx 0.57721$).    This integral was mentioned in  as in  , but the solutions I've got uses corollaries from . Can you give me a simple solution (not using much advanced theorems) or at least some hints. I have to compute this integral $$\int_{0}^{\infty} \frac{dt}{1+t^4}$$ to solve a problem in a homework. I have tried in many ways, but I'm stuck. A search in the web reveals me that it can be do it by methods of complex analysis. But I have not taken this course yet. Thanks for any help. Are global variables bad? Why do first years cross the lake to get to the castle? Sometime in the 1970s (I think) I saw a really awful film set in a small town by a lake. The film opened with some people camping out in the woods. One of them was zipped up in a sleeping bag. Something (as yet unidentified) moved in between the sleeping camper and the camera, and we heard a "crunch." When the creature moved off, we saw that it had bitten the head off the camper, causing a fountain of blood to spout of of the neck. Far from being shocking or gory, it was so badly done as to be laughable.  The main story was that these huge and nasty mutated creatures were coming out of the lake and eating people. A local industrial company was under suspicion for poisoning the lake, but repeated water tests showed it to be clean.  In the end, someone had the idea of testing the water at the bottom of the lake, which revealed it to be heavily poisoned with mercury. As mercury is much heavier than water, it had sunk, so the previous tests (done from a small row boat) had missed it as they only sampled the water at the surface.  They got it all sorted out eventually, and the bad guys ended up in prison.  After the credits had rolled, and you thought it was all over, another monster reared up in front of the camera and roared. I think we were supposed to go "Oh no, it's not all over!" However, the few people stupid enough not to have left by now laughed at the ridiculous sight and left, shaking their heads wondering why they had bothered!  I have a morbid fascination to see it again. Anyone have any idea what it was called? In my experimentation, I've used only BJTs as switches (for turning on and off things like LEDs and such) for my MCU outputs. I've been repeatedly told, however, that N-channel enhancement-mode MOSFETs are a better choice for switches (see  and , for examples), but I'm not sure I understand why. I do know that a MOSFET wastes no current on the gate, where a BJT's base does, but this is not an issue for me, as I'm not running on batteries. A MOSFET also requires no resistor in series with the gate, but generally DOES require a pull-down resistor so the gate doesn't float when the MCU is rebooted (right?). No reduction in parts count, then. There doesn't seem to be a great surplus of logic-level MOSFETs that can switch the current that cheap BJTs can (~600-800mA for a 2N2222, for example), and the ones that do exist (TN0702, for example) are hard to find and significantly more expensive. When is a MOSFET more appropriate than a BJT? Why am I continually being told that I should be using MOSFETs? How do I survive in the Nether? Whenever I travel to the Nether in Minecraft, I almost instantly get blasted to smithereens and chopped up into little pieces.  How do I survive in the Nether, at least long enough to build some sort of shelter and get situated? I've just had to write a string reverse function in C# 2.0 (i.e. LINQ not available) and came up with this:  public string Reverse(string text) {     char[] cArray = text.ToCharArray();     string reverse = String.Empty;     for (int i = cArray.Length - 1; i &gt; -1; i--)     {         reverse += cArray[i];     }     return reverse; }   Personally I'm not crazy about the function and am convinced that there's a better way to do it. Is there? 403 Forbidden with Java but not web browser? C Scanf suddenly stopped reading in values In Visual Studio, we've all had "baadf00d", have seen seen "CC" and "CD" when inspecting variables in the debugger in C++ during run-time.  From what I understand, "CC" is in DEBUG mode only to indicate when a memory has been new() or alloc() and unitilialized.  While "CD" represents delete'd or free'd memory.  I've only seen "baadf00d" in RELEASE build (but I may be wrong).  Once in a while, we get into a situation of tacking memory leaks, buffer overflows, etc and these kind of information comes in handy.  Would somebody be kind enough to point out when and in what modes the memory are set to recognizable byte patterns for debugging purpose? What's the difference between &lt;b&gt; and &lt;strong&gt;, &lt;i&gt; and &lt;em&gt; in HTML/XHTML? When should you use each? Vacuum sealing vs. water displacement method when doing longer sous vide cooking Modernist Cuisine recommends that for longer sous vide cooking (times greater than 36 hours) that bags are vacuum sealed rather than just using the water displacement method to remove the air from a ziploc bag.  What is the reason for this? Will I be losing something essential if I just use a regular ziploc bag without vacuum sealing? Video lectures on graduate level Classical Electrodynamics This is a rather broad question. Does anyone know of good video lectures for graduate level classical electrodynamics? Showing arrowheads in line end using QGIS?