Laptops to Install Ubuntu
What are the system requirements for each flavour of Ubuntu Desktop?
I'm trying to figure out a recursive formula for the number of possible distinct binary trees at any depth d. I haven't been able to find any sort of sources on this.  basically, at depth 0, the only binary tree is the empty one so 0, 1  then at depth 1 the only possibility is a single node so 1, 1  at depth = 2 there are 3 possibilities, and at depth 3 I counted 21 possibilities.  I haven't been able to figure out some recursive reasoning for what 4 could be and so on. The only thing I have in place is that there will always be 1 for the full tree. Let $X=(0,1]$ and $d(x,y)=\left|\frac{1}{x}-\frac{1}{y}\right|$. I've proven $(X,d)$ is a metric space but I don't know how to show its completeness. How can I do that? ls command operating differently depending on recipient Showing the sequence converges to the square root For any $a &gt; 0$, I have to show the sequence $x_{n+1}$ $=$  $ \frac 12$($x_n+ $ $ \frac {a} {x_n}$)  converges to the square root of $a$ for any $x_1&gt;0$.  If I assume the limit exists ( denoted by $x$) then,  $x$ $=$  $ \frac 12$($x+ $ $ \frac {a} {x}$) can be solved to $x^2 = a$  How could I show that it does exist? I have recently installed lubuntu 11.10 on my old laptop (acer aspire 5315 celeron) and observed that fan is not working properly on lubuntu side.I find it strange that it is working perfectly under window vista.   How could I solve this problem? $k^{\phi(l)} + l^{\phi(k)} \equiv1\pmod{lk}\,$ if $\,\gcd(l,k)=1$ I would like to prove the following equality: $$k^{\phi(l)} + l^{\phi(k)} \equiv1\pmod{lk}$$if $\gcd(l,k)=1$. What methods can I use? Thank you for your help. This community wiki explains the current restrictions by the United States of America on the entry of individuals who may pose a risk of transmission of the SARS-Cov2, the virus which causes the Covid-19 disease. Is it ethical to omit the PhD credential from my resume? I am applying for a Statistical Programmer position at a commercial research organization (CRO), and I am wondering if it is unethical to omit my PhD in Statistics from my resume?  All of my degrees (Bachelor's, Master's, PhD) are in Statistics, and I am just wondering if it would be ethical to just list my Bachelor's and Master's degree on my resume, and indicate my experience as a RA while I was a PhD student as my "work experience"? (Since this Statistical Programmer position only requires Master's degree plus some years of experience)  I am asking this question because I do not want to do anything unethical/cause me troubles later on. How to not have an equation in the first line using the align environment? How many ways can N elements be partitioned into subsets of size K? Is there a \subsubsubsection command? I could do \subsection{} and \subsubsection{} but not \subsubsubsection{}. This command does not seem to be available in LaTeX. Is there an alternative command? Is Con modifier × level added to HP every level-up? In , the votes clearly show that the os.path.splitext function is preferred over the simple .split('.')[-1] string manipulation. Does anyone have a moment to explain exactly why that is? Is it faster, or more accurate, or what? I'm willing to accept that there's something better about it, but I can't immediately see what it might be. Might importing a whole module to do this be overkill, at least in simple cases?  EDIT: The OS specificity is a big win that's not immediately obvious; but even I should've seen the "what if there isn't a dot" case! And thanks to everybody for the general comments on library usage. Why are C# interface methods not declared abstract or virtual? Why is it called Area 51? According to : "We like the little aliens."  This seems well targeted to appeal to the Stack Overflow / Server Fault / Super User audience, but way off the mark if the goal is to "make the Internet a better place to get expert answers to your questions."    There are experts who aren't interested in or focused on technology oriented topics.  Little aliens are unlikely to be something that someone interested in organizing a site on gardening would gravitate too.  No, I'm not suggesting that no one interested in gardening would be bother to look at a site with little aliens, but won't it be likely that the sort of mass appeal to to a very broad cross section of the internet will be lacking? Does the rank-nullity theorem hold for infinite dimensional $V$? Should flagging a question for closure prevent close-voting? Back in April, I flagged a post as "not a real question".  The post was subsequently closed and reopened, then closed again and finally just reopened a 2nd time a short time ago.  I still firmly believe the post is not acceptable for SO, so I went to use my recently acquired close vote privilege and was greeted with the following messsage:    I specifically clicked close and not flag (and figuring I just clicked in error, I tried again and got the same message).  I do understand that, in the new closing system, flagging for closure is treated very much like a close vote (since it throws it to the close vote queue) except no vote is actually recorded.  My issue is why should by flag be counted as a close vote when I never actually voted to close. C++ display stack trace on exception How do I grep for lines containing either of two words, but not both? I'm trying to use grep to show only lines containing either of the two words, if only one of them appears in the line, but not if they are in the same line.  So far I've tried  grep pattern1 | grep pattern2 | ... but didn't get the result I expected. How to transit through Delhi without a visa?