Sorting HashMap based on values in java
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Proving $f' = - \frac{\partial{F}/\partial{x}}{\partial{F}/\partial{y}}$ What constitutes protons? When I see pictures, I can't understand. Protons are made of quarks, but some say that they are made of 99% empty space. Also, in this illustration from Wikipedia, what's between the quarks? Is there any way to kill a Thread? Is it possible to terminate a running thread without setting/checking any flags/semaphores/etc.? So I've been experiencing this in the last few days: sometimes when someone replies to my comment, and I reply to the reply, then the "add/show 1 more comment" link appears immediately after I post my comment. However, when I click it, it disappears and nothing is shown.  I don't think it's that OP is posting two comments of which he deletes the second one, because this has happened to me several times, even when I was replying within 2-3 seconds.  I do, however, believe that this is more or less the same bug as , except that I don't have to reload the page in order the link to be gone, and I also seem to be getting the erroneous behavior only if I reply to a comment which is itself a reply to an earlier comment of mine.  Unfortunately, I wasn't careful enough to take a screenshot last time this happened, but here's what I am talking about for those who like visual demonstration better: Learning Regular Expressions Why do we say there is an overall negative charge on the intracellular side of the plasma membrane at rest, and an overall positive charge on the extracellular side when both potassium and sodium are positively charged ions, and they are in relatively equal amounts on either side? It seems to me that both sides should be positively charged, and I can't get my head around it. Given $|z|&lt;1$ with $z \in \mathbb{C}$ prove $\lim_{n \to \infty} z^n=0$.  My attempt given $\epsilon &gt;0$ we wish to show that there exists $\delta &gt;0$ such that $n&gt; \delta$ means $|z^n-0| &lt; \epsilon$.  For $n \in \mathbb{N}$. We have $|z^n|=|z|^n$. We wish $|z|^n &lt; \epsilon$. This means,  $$n \ln |z| &lt; \ln \epsilon$$  But because $\ln |z|&lt;\ln 1=0$ dividing both sides by $\ln |z|$ gives:  $n&gt; \frac{\ln \epsilon}{\ln |z|}$  So that's what we choose for $\delta$.   My question is is how can we get away from the assumption that $n \in \mathbb{N}$. Or is this correct even with the assumption? Suppose that C is a closed convex subset of $\mathbb R^n$ and $x \in \mathbb R^n$. The projection of $\mathbf x$ onto C is the closest point $\mathbf y \in C : \mathbf z = \mathbf y$ minimizes ||$\mathbf z - \mathbf x$||$_2$ over all $\mathbf z \in C$.  (a) Show that the minimum exists.  (b) Show that there is only one minimizer: that is, show that if $\mathbf y_1$ and $\mathbf y_2$ both minimize ||$\mathbf x - \mathbf z$|| then $\mathbf y_1 = \mathbf y_2$   My ideas:  For (a), to show that the minimum exists I will need to show that it is closed and bounded. We already know it's closed because C is a closed convex subset so I just need to show it's bounded. Am I wanting to minimize ||$\mathbf x - \mathbf z$||$_2$? This is just the Euclidean norm which would be $\sqrt{(\mathbf z - \mathbf x)^2}$=$\sqrt{\mathbf z^2 -\mathbf z \mathbf x -\mathbf x \mathbf z + \mathbf x^2}$. I'm not sure where to go from here...  For (b) I want to use proof by contradiction- so I will assume that $\mathbf y_1$ and  $\mathbf y_2$ both minimize the function and then I'll somehow see that they are in fact equal. How do I set up this argument? How does ownership in fractional shares work? I've been trying to find out some more information about fractional shares, and how they work. I understand conceptually, you own x% of a share rather than x "full" shares, but I'm curious about how such a system is implemented.  As I understand it, in a "traditional" purchase of shares, the role of a broker is to act as an executor on your behalf, and does not hold any assets themselves. In the case of a fractional share, is this then not the case? For example, the broker holds the complete shares, and then just ensures that they keep an internal record of each partial owner in their system? So there would be no external record of partial ownership?  Thanks! I often hear about subatomic particles having a property called "spin" but also that it doesn't actually relate to spinning about an axis like you would think. Which particles have spin? What does spin mean if not an actual spinning motion? Story identification - "bless the beasts that bless us" I'm trying to trace what was probably a short story rather than a full novel from my childhood.  I think it starts in the present day (so the 80s or thereabouts) and there was some kind of alternate reality bleed which meant there were (i think) ghost boars or pigs, they were becoming more physical with time, and so problematic. The family escaped when the family dog led them to and through a portal which they couldn't perceive to a safer place.  In the end, they ended up in some kind of rural community who had a religion / custom that required them to say "Bless the beasts that bless us" but some folk shortened it to BTBTBU which irritated the girl who was the principle character.  I used to read a lot of kids short story sci-fi and fantasy including Nicolas Fisk but I don't know whether this was from a compilation of several authors or a single author's collection. The ship flying away from Rey in her flashback of being left on Jakku looks like one of the ships in the group that takes her away when she is captured.  If so, and it is a First Order ship that dropped her off, this is an interesting Easter egg. Redirect, Change URLs or Redirect HTTP to HTTPS in Apache - Everything You Ever Wanted to Know About mod_rewrite Rules but Were Afraid to Ask This is a  about Apache's mod_rewrite.   Changing a request URL or redirecting users to a different URL than the one they originally requested is done using mod_rewrite. This includes such things as:   Changing HTTP to HTTPS (or the other way around) Changing a request to a page which no longer exist to a new replacement. Modifying a URL format (such as ?id=3433 to /id/3433 ) Presenting a different page based on the browser, based on the referrer, based on anything possible under the moon and sun. Anything you want to mess around with URL   Everything You Ever Wanted to Know about Mod_Rewrite Rules but Were Afraid to Ask!  How can I become an expert at writing mod_rewrite rules?   What is the fundamental format and structure of mod_rewrite rules? What form/flavor of regular expressions do I need to have a solid grasp of? What are the most common mistakes/pitfalls when writing rewrite rules? What is a good method for testing and verifying mod_rewrite rules? Are there SEO or performance implications of mod_rewrite rules I should be aware of? Are there common situations where mod_rewrite might seem like the right tool for the job but isn't? What are some common examples?   A place to test your rules  The  web site is a great place to play around with your rules and test them. It even shows the debug output so you can see what matched and what did not. OpenSSL and error in reading openssl.conf file I am starting to learn some Regex, therefore I use this command repeatedly:  grep pattern /usr/share/dict/american-english    Only the part with pattern changes, so I have to write the long expression "/usr/share/dict/american-english" again and again.   Someone made the remark that it is possible to expand an argument of a command from the command history by typing cryptic character combinations instead of the full expression.  Could you tell me those cryptic character combinations ? What does "+6 to hit, Hit: 13 (2d8 + 4)" mean in a creature's stat block? My friends and I are very new to D&amp;D, played like 3 times. In a monster's stats next to weapon damage it says stuff like "+11 to hit" and "Hit: 5 (1d8+1)". For the premade characters it just says things like "+4, 2d6 + 2 slashing", though. Why are there two "hit" numbers for monsters? Which do I use for the d20 roll to hit against a target's AC?  I mean for example like in the Ogre entry in the "" article on monsters. I installed Ubuntu 12.10 and entered a password in SeaHorse. I would like to remove the password of "Default" but I get this error :  GDBus.Error:org.freedesktop.Secret.Error.NoSuchObject: The collection does not exist   Is there a fix or a way to bypass modify the password ? Matrix reciprocal positive to prove $λ_{max⁡}=n$ Suppose we have $n\times n$ matrix $A$ having only positive elements and satisfying the property $a_{ij}=1/a_{ji}$ (a matrix satisfying this property is called a reciprocal matrix).  If its largest eigenvalue $λ_{max}$ is equal to $n$, then the matrix $A$ satisfies the property (consistency property) $a_{ij}a_{jk}=a_{ik}$ where $i,j,k=1,2,...,n$.    I already found an example of $5\times 5$ reciprocal matrix  to show this condition:  \begin{bmatrix}1&amp;1/2&amp;1&amp;1&amp;1/4\\2&amp;1&amp;2&amp;2&amp;1/2\\1&amp;1/2&amp;1&amp;1&amp;1/4\\1&amp;1/2&amp;1&amp;1&amp;1/4\\4&amp;2&amp;4&amp;4&amp;1\end{bmatrix}  It has simple characteristic equation $λ^5-5λ^4=0$, so the eigenvalues of matrix $A$ are $λ=0$ and $λ=5$ and it's shown that $λ_{max}=n=5$.  Is there anyone can help me to give another positive reciprocal matrix example  that has simple characteristic equation and integer number as its eigenvalues ($4\times 4, 5\times 5$ or $6\times 6$ matrix)? Underworld Connections: Tapping the Land for mana and ability? Does scikit-learn have forward selection/stepwise regression algorithm? I'm working on the problem with too many features and training my models takes way too long. I implemented forward selection algorithm to choose features.  However, I was wondering does scikit-learn have forward selection/stepwise regression algorithm?