I'm trying to install ns3 and, before that, I need to run the command below: sudo apt install gir1.2-goocanvas-2.0 python-gi python-gi-cairo python-pygraphviz python3-gi python3-gi-cairo python3-pygraphviz gir1.2-gtk-3.0 ipython ipython3  After running this command, I get this error: The following packages have unmet dependencies:  ipython : Depends: python-ipython (= 5.5.0-1) but it is not going to be installed  python-gi : Depends: python2 (&lt; 2.8) but it is not going to be installed              Depends: python2 (&gt;= 2.7~) but it is not going to be installed              Depends: python2:any (&lt; 2.8)              Depends: python2:any (&gt;= 2.7~)  python-gi-cairo : Depends: python-cairo (&gt;= 1.11.1) but it is not going to be installed                    Depends: python2 (&lt; 2.8) but it is not going to be installed                    Depends: python2 (&gt;= 2.7~) but it is not going to be installed                    Depends: python2:any (&lt; 2.8)                    Depends: python2:any (&gt;= 2.7~) E: Unable to correct problems, you have held broken packages.  What should I do to solve this problem?
After upgrading from 10.04 to 12.04 I am trying to install different packages.  For instance ia32-libs and skype (4.0).  When trying to install these, I am getting the 'Unable to correct problems, you have held broken packages' error message.   Output of commands:  sudo apt-get install -f Reading package lists... Done Building dependency tree        Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.   After running this:  sudo dpkg --configure -a foo@foo:~$ sudo apt-get install -f Reading package lists... Done Building dependency tree        Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Let $a, b, c \in \mathbb{N}$. Show that if $a^2+b^2=c^2$ then $gcd(a,b)=gcd(a,c)=gcd(b,c)$.  Using basic divisibility criteria I couldn't advance anything. How long do seasons last? In the Kittens Game, how long (in real life minutes) do seasons last? Go to  Add a few photos to a photo album Go back to All Photos   See all of the photos there, even ones you copied to the Album. No problem here, per se. At least not yet.  What if you want to delete photos that you did not copy to that album?  Where is the selector or filter that filters those "in an album already" photos from this main view?  Or is there a way to create such a filtered view such that I can then cherry-pick photos for deletion? If Obi-Wan and Yoda were trying to keep Luke safe from Vader, why would they let him keep the Skywalker name? find examples of two series $\sum a_n$ and $\sum b_n$ both of which diverge but for which $\sum \min(a_n, b_n)$ converges Find examples of two series $\sum a_n$ and $\sum b_n$ both of which diverge but for which $\sum \min(a_n, b_n)$ converges. To make it more challenging, produce examples where $a_n$ and $b_n$ are positive and decreasing.  Edit: This problem is taken verbatim from Exercise 2.7.11 on page 68 of Abbott's Understanding analysis. We have a system hosting many websites for our customers, and inside that system there is a method that non-live customers can view their sites before we turn them on.  Say the link is something like this: ourbigcompany.com/customer/domain=thisisanewsiteurl  Those links are not linked to anywhere outside a secure login - they are only sent to the customer via email. They are publicly viewable, as they have to be, but that's not the real problem.  The real problem is that somehow Bing is getting hold of them and trying to crawl the sites.   I know how to stop the crawling, but that would be like treating the symptoms without fixing the problem.  We log the traffic and there is no referrer - so that is not helpful.  If I change the querystring value for a site, Bing has it within hours. I need to figure out where Bing is getting the links from so that I can close what is obviously a security hole, but I am not sure how.   Any ideas on how to figure that out? Making the background of an image transparent in Gimp I have some jpg images and I need for each of them to have a transparent background.  I have GIMP as a graphic tool.   I need to put them in a web page and I need to see just the main element and have a transparent background. GPG can't check signature When should "no problem" replace "you're welcome" as a response to "thank you"? Posting a Solution of a problem that You faced to Help Newbies About an Hour ago, I faced a problem and tried different ways to solve it.  At last I was going to post my Question on Stack Overflow, but the last trick which came in my mind worked, and the problem got resolved.    Now, if I want to post that problem on Stack Overflow with the solution which worked for me, for the purpose to help other newbies to get their answer if they face the same problem, what is the proper way of posting such solution to a problem? I know that non-married lovers address each other by saying “This is my girlfriend/boyfriend.” I know that married couples address each other by calling “my wife/husband”.  I also know that gay lovers who are not married (yet?) address each other by saying "my boyfriend" (for gays) and "my girlfriend" (for lesbians).  But if they are married, how do they address each other?  And how do we describe them? I mean if they are gays, are they “husband and husband” or “husband and wife” (one of them acts like the wife)? And if they are lesbians, are they “wife and wife” or “husband and wife” (one of them acts as the husband)?  I know they can be referred to as a gay couple or gay lovers from , but I couldn't find the answer to address each of the two. Plural nouns in nominal compounds I wonder whether there are rules or guidelines regarding plural nouns in nominal compounds. For example a compound university students list. If there are many lists and many universities is it grammatically correct to say universities students lists? Must all elements be in the plural form or can some be left in singular, even though the meaning is plural? I've seen an expression universities student lists; is it correct? Image in a cell with a hyperlink How do I URL encode a string How do I get the last column text to be at the bottom of the row?  That is I want the XXX to be aligned with the line containing the arrow. I tried playing around with \multirow{3}{-3ex}{XXX}, but obviously I don't understand \multirow. Code: \documentclass{article} \usepackage{tabularx} \usepackage{booktabs} \usepackage{multirow}  \begin{document}     \begin{tabularx}{\linewidth}[t]{l X p{1.3cm}}         &amp; Header &amp; Title \\\cmidrule(lr){2-2}\cmidrule(lr){3-3}         a. &amp; Some text text text text text text text text text text text text text text              text text text text text text text text text text              Want XXX on this line $\rightarrow$%          &amp; XXX\\     \end{tabularx} \end{document} Statistics module doesn't show the "Enable access log" checkbox I dont know what to do to show "Enable access log" option.  I activated logging all messages and checked all statistics permissions.  Thanks. In a bash shell script, writing a for loop that iterates over string values In bash, I know that it is possible to write a for loop in which some loop control variable i iterates over specified integers.  For example, I can write a bash shell script that prints the integers between 1 and 10: #!/bin/bash  for i in {1..10} do  echo $i done  Is it possible to instead iterate over a loop control variable that is a string, if I provide a list of strings?  For example, suppose that I have a string fname that represents a file name.  I want to call a set of commands for each file name.  For example, I might want to print the contents of fname using a command like this: #!/bin/bash  for fname in {&quot;a.txt&quot;, &quot;b.txt&quot;, &quot;c.txt&quot;} do  echo $fname done  In other words, on the first iteration, fname should have the value fname=&quot;a.txt&quot;, while on the second iteration, fname should have the value fname=&quot;b.txt&quot;, and so on.  Unfortunately, it seems that the above syntax is not quite correct.  I would like to obtain the output:  a.txt b.txt c.txt  but when I try the above code, I obtain this output:  {a.txt, b.txt, c.txt}  Can you please help me determine the correct syntax, so that I can iteratively change the value/contents of the variable fname?  Thank you for your time. What exactly happens to the signals hitting a common mode choke? I'm trying to better understand the principles behind the common mode choke. I made a few drawings to clarify.  &nbsp; Differential Mode Signals  Differential currents (driven by differential voltages) create equal but opposite magnetic fields B in the inductor core:    These magnetic fields cancel each other out, so the net flux in the core is zero. As such, these differential currents don't "feel" any impedance.  &nbsp; Common Mode Signals  In contrast, common mode currents generate equal and additive magnetic fields in the core. That's why they "feel" a high impedance, and cannot get through (or getting through means they are highly attenuated).    But what exactly happens? I have several theories, which I will describe below.  &nbsp; Common Mode Signals - Theory 1  My first thought would be that the common mode signal hits the choke and creates a magnetic flux inside. By doing this, lots of energy is lost (hysteresis and perhaps other effects) as heat. Only a small part gets through:      What kind of common mode choke would behave in this particular way? "Burning up" the voltage spike seems a very desirable effect to me.  &nbsp; Common Mode Signals - Theory 2  Perhaps the voltage spike doesn't really get the chance to build up much magnetic flux in the core, or maybe the core is simply not "lossy" enough. The voltage spike bounces off the core and turns back. Only small part gets through:    Although the system on the right side of the choke is protected, the system on the left has to deal with reflected signals. Nasty things like standing waves might appear.  &nbsp; My questions  I've got a few questions for you:   Do you think theory 1 or theory 2 is most plausible? Do you think certain types of common mode chokes tend to behave as described in theory 1, others like in theory 2? Perhaps both of my theories are just plain wrong. If so, what actually does happen?   Please enlighten me. Does Google use the Meta Description Tag for Description of Page? Show that the Sorgenfrey line does not have a countable basis.