How to prove even subsets equal to odd subsets?
number of subsets of even and odd
Mechanism to prevent edits without approval? I would say a quarter to half my questions end up getting edited the vast majority of which end up dramatically changing the context of my question. I'm not against good advice (I've acted on about 2% of all the criticisms I have ever had about my work since they were actually thoughtful) though I think since I joined overflow sites years after I've had a good grip on most of the material I work with people are seeing low reputation and presuming that equates to low levels of comprehension.  Regardless of the reasoning behind people making edits is there an option I can use that would require my approval in order to commit an edit to my questions?   I have no interest in spamming questions in order to artificially boost my reputation. I am getting tired of having to add bullet points telling people to ask for clarifications instead of editing my posts. Having to correct my posts so often reduces my desire to ask the question if I have to review the question again (even with the revision pages available). As this is a discussion there is no reason to edit this post, I will be happy to revise my own if you leave comments as I actively follow questions I participate in though the office of redundancy redundancy requires that I state I know what I am asking.   For example, say I post about Kubuntu (which by default uses KDE) and someone edits it changing the OS to Ubuntu (which uses Gnome by default). Then, answers become Gnome-oriented for a KDE question and the entire context has been changed--negating the point of asking the question in the first place. Intuitive explanation of variance and moment in Probability While I understand the intuition behind expectation, I don't really understand the meaning of variance and moment.   What is a good way to think of those two terms? Let's say it again, we all make mistakes, and I have just made one.  A brief history: I was doing some stuff on a VPS (Debian) I'm renting, when I noticed some strange behaviour. Using the netstat command I saw an non-authorized connection through SSH. I didn't know what to do, so I decided to close his connection using iptables:  iptables -A INPUT -p tcp --dport ssh -s IP -j DROP   But I am tired, and I wrote  iptables -A INPUT -p tcp --dport ssh -j DROP   and I kicked myself (and everyone else) out...  How do I fix this? Lower the amount of reputation needed to comment is a great example of people coming from Google and using answers as comments.  I understand the reputation threshold is there to prevent spam, but Answers are just as prone to spam as comments and you can post them at reputation 1. Furthermore there are already flags in place as a preventive measure for both.  Essentially the reputation threshold of comments is forcing people to use the site in ways the designers did not intend. Removal of the reputation cap would also make the site more new user friendly as newbies that use the site in this manner are commonly given a unfriendly welcome in the form of downvotes from people who forget you need 50 rep to post comments. Can I look at the upgrade log after a distribution upgrade? I've upgraded to Ubuntu 12.04 and did it . I didn't look at the "packages to remove" section before clicking next - I've done Ubuntu upgrades many times and assumed it was just the normal set of obsolete library packages etc. But I do tend to watch the terminal text go by and see what it's doing, and I saw it removing a number of packages I wanted. I guess these are packages that aren't on the CD that can't co-exist with the new Ubuntu.  Anyway, I want to find which packages have been removed. So does the update log get saved somewhere?  Then I can start doing some grepping on it and then reinstall the packages I did want. Add a "back to top" link The left-nav is great - I like it, users who don't can disable it. Perfect world. Now it's stickied it's always there too, which is really useful.  When I'm navigating in areas not directly linked to in the left nav and have scrolled down, I often want to re-use the other navigation. This means scrolling up. Which is fine, of course it's how websites work.  However, if the left-nav had a "Top" link which took the user to the very top of the page it would be great for getting back to specific contextual menus and things that are not linked to in the left-nav.  For example, if I'm viewing questions on a specific tag and I've scrolled down, I sometimes want to get back up to the top to remove a tag, or change from "Latest" to "Featured" etc. Although clicking the "Questions" link in the left-nav takes me back to the top, it removes the tag(s) I was searching with.  There are other use cases where this would be useful, like long questions and answers (Etc). So I think a "Top" link in the left nav would be very useful.    I think this is different to the  as it doesn't mention the left-nav, and my question is suggesting this idea because we have a good place to put it and it'll be a useful addition to the left-nav. Finding a distribution from the sum of two random variables in a joint trinomial distribution Let X and Y have a trinomial distribution with join probability function:  $ f(x,y) = \frac{n!}{x!y!(n-x-y)!}p^x q^y (1-p-q)^{n-x-y}; x=0,1,...n, y=0,1,...n$  Let $T=X+Y$  I can't seem to figure out where to go exactly. Here's where I am at:  $\sum_{x=0}^{n} \frac{n!}{x!y!(n-x-y)!}p^x q^y (1-p-q)^{n-x-y}\mbox{ substitute in Y=T-X}$ $\sum_{x=0}^{n} \frac{n!}{x!(t-x)!(n-t)!}p^x q^{t-x} (1-p-q)^{n-t}$   I think I could I figure out the algebra.. if I could just see what to do with the summation. I know I have to involve a t somewhere, but I'm not sure. Maybe somebody could just show me how to set up my summation correctly with the substitution? Which Content Management System (CMS)/Wiki should I use? This is a general, community wiki  question to address non-specific "I need a CMS or Wiki that does x, y, and z..." questions.  If your question was closed as a duplicate of this question and you feel that the information provided here does not provide a sufficient answer, please open a discussion on .    I have a list of features that I want for my website's Content Management System (CMS) - where can I find a [free] script that includes all of them? Proving $(A\le B)\vee (B\le A)$ for sets $A$ and $B$ How to find Windows 7 File Transfer History? Is it possible to find out which files are transferred to an external usb flash drive in certain period of time?   To be more clear. If I/someone have a flash drive and take some data from me. How do I know which files are copied? Finding out file copy hostory could be also a work around. How to reduce VM size? I am trying to find a book (young adult) where the devil is the protaganist, and other gods appear as characters I believe it was written by a teenager, and might have a sequel.   It has been many years since I read it, but I believe it had the devil acting like a regular human. He wasn't evil. I think it incorporated a lot of (gods/characters) norse, roman, Christian, and pagan. Why should you not use Number as a constructor? Visa for Istanbul trip during layover I am an Indian (Indian Passport) presently in Kano, Nigeria on a business visa. I am going back to Mumbai on 22 Sept by Turkish Airlines with a 12 hour layover time in Istanbul.  We plan to see the city during this time.  Can I get a visa on arrival? I came across this :     Unbelievable as it may seem, many individuals that fought in the   American Revolution were still alive in 1839, the year the world was introduced to photography. (choose the error - the 'answer' is in bold)   It noted that the reason "that fought" is wrong is that 'The relative pronoun “that” may not be used to refer to people (“individuals”) and should be replaced with the relative pronoun “who.”'   I had thought that the word "that" could refer to both people and objects (while which was reserved for objects and who reserved for people). Am I wrong? At one point, I decided to make friends with the low-lying spectrum of QCD. By this I do not mean the symmetry numbers (the "quark content"), but the actual dynamics, some insight.  The pions are the sloshing of the up-down condensate, and the other pseudoscalars by extending to strangeness. Their couplings are by soft-particle theorems. The eta-prime is their frustrated friend, weighed down by the instanton fluid. The rho and omega are the gauge fields for flavor SU(2), and A1(1260) gauges the axial SU(2), and they have KaluzaKlein-like echoes at higher energies, these can decay into the appropriate "charged" hadrons with couplings that depend on the flavor symmetry multiplet. The proton and the neutron are the topological defects. That accounts for everything up to 1300 but a few scalars and the b1.  There are scalars starting at around 1300 MeV which are probably some combination of glue-condensate sloshing around and quark-condensate sloshing around, some kind of sound in the vacuum glue. Their mass is large, their lifetime is not that big, they have sharp decay properties.  On the other hand, there is nothing in AdS/QCD which should correspond to the sigma/f0(600), or (what seems to be) its strange counterpart f0(980). While looking around, I found this discussion: . The literature that it pointed to suggests that the sigma is a very unstable bound state of pions (or, if you like, tetraquarks).   gives strong evidence for an actual pole;  gives a more cursory review. The location of the pole is far away from the real axis, the width is larger than the mass by 20% or so, and the mass is about 400MeV. The authors though are confident that it is real because they tell me that the interpolation the interactions of pions is safe in this region because their goldstone properties dominate the interactions. I want to believe it, but how can you be sure?  I know this particle was controversial. I want to understand what kind of picture this is giving. The dispersion subtraction process is hard for me to visualize in terms of effective fields, and the result is saying that there is an unstable bound state.  Is there a physical picture of the sigma which is more field theoretical, perhaps even just an effective potential for pions? Did anyone who convinced himself of the reality of the sigma have a way of understanding the bound state properties? Is there an analog unstable bound state for other goldstone bosons? Any insight would be welcome. How to start Ubuntu in Console mode Database schema documentation for the public data dump and SEDE Stack Exchange releases "data dumps" of all its publicly available content roughly every three months , and also makes that information queryable over the Internet at the  (SEDE) (updated weekly, on Sunday). Over time, as new features and other bits of data are introduced to Stack Exchange sites, the "anatomy" of the data dump is likely to change. I'm using Dataloader to Upsert a Child Account to Parent Account using an external ID.  When the Upsert is complete, the Child overwrites the parent, it's not not connecting the Child Account to the Parent Account.  ((See Answer Below)) Can't get armature to move mesh! I am trying to get an armature to move one limb on a deer I have made. Here is my design process!   I made the body and limbs as separate meshes. I wasn't sure how to create limbs out of the body of the mesh and make them look good. I tried joining  the meshes, creating the armature and setting automatic weights and then moving the armature in pose mode. The mesh would not move with the armature I thought maybe it was because many vertices between the mesh and the limb were crossing so I thought maybe that was why the armature was not moving the limbs I used the cut tool to remove the intersecting mesh on the limb and the body so that there were no intersecting vertices.  I then joined this set of meshes and created a new armature, set the weights to automatic and tried to move the mesh in pose mode and it still won't work.    What should I do? I don't know what else to try. I have been following any other online instructions exactly.  File Link: