A tangible example of Persistent Layer and its difference with DAL layer?
What is the use of a persistence layer in any application?
Given Newton's third law, why are things capable of moving? What characters are valid in a Java class name? What other rules govern Java class names (for instance, Java class names cannot begin with a number)? Suppose I have a question in my mind that I think is answerable but because I don't already know the answer, I'm not sure how to express in a way that makes it clear and definitively answerable. I suspect that someone more knowledgable than me would understand what I'm trying to get at though and could help me word the question properly.  Is there a good place to find this sort of help? Convert string to Title Case with JavaScript Divergent infinite series $n!e^n/n^n$ - simpler proof of divergence? $$ \sum_{n=1}^\infty \frac{n!e^n}{n^n} $$ Where $e$ is Euler's number.  Recently on calculus class we were covering convergence tests and my group got stuck with this infinite series. Our calculus teacher told us that it diverges but he doesn't see any elementary way or simple test to prove it. He told us something about Euler's Gamma function and said that he knows it diverges because of Stirling's formula but this is not quite our level yet.  I tried to think about it myself but I established only that this  is some kind of an edge case. We could generalize the problem to series of $\frac{n!a^n}{n^n}$. Then, from the ratio test we know that it converges for $a &lt;e$ and diverges for $a&gt;e$. For $a=e$ the test is inconclusive. I've also tried to compare it with various divergent series, but nothing worked...  Does anybody have any idea for a simple solution? Multiple file upload in php count lines in a file I'm sure there are many ways to do this: how can I count the number of lines in a text file?  $ &lt;cmd&gt; file.txt 1020 lines PHP Session data not being saved I have one of those "I swear I didn't touch the server" situations. I honestly didn't touch any of the php scripts. The problem I am having is that php data is not being saved across different pages or page refreshes. I know a new session is being created correctly because I can set a session variable (e.g. $_SESSION['foo'] = "foo" and print it back out on the same page just fine. But when I try to use that same variable on another page it is not set! Is there any php functions or information I can use on my hosts server to see what is going on?  Here is an example script that does not work on my hosts' server as of right now:  &lt;?php session_start(); if(isset($_SESSION['views']))     $_SESSION['views'] = $_SESSION['views']+ 1; else     $_SESSION['views'] = 1;  echo "views = ". $_SESSION['views']; echo '&lt;p&gt;&lt;a href="page1.php"&gt;Refresh&lt;/a&gt;&lt;/p&gt;'; ?&gt;   The 'views' variable never gets incremented after doing a page refresh. I'm thinking this is a  problem on their side, but I wanted to make sure I'm not a complete idiot first.  Here is the phpinfo() for my hosts' server (PHP Version 4.4.7): Updating .class file in jar Are all limits solvable without L'Hôpital Rule or Series Expansion Benchmarking hosting providers IO with Bonnie Print out elements from an array with a comma between elements except the last word How do I wrap a macro definition in an environment? I'm creating a style file, and want to store the body text of the abstract environment so that I can put it on my custom titlepage. I could have required that my users enter the abstract as  \customabstract{Abstract text goes here}`   which I would have implemented as something like  \newcommand{\customabstract}[1]{\gdef\abstracttext{#1}}   However, I would prefer that the user is able to use environment notation,  \begin{customabstract}Abstract text goes here\end{customabstract}   To do this, I thought I could define something like  \newenvironment{customabstract}{\gdef\abstracttext\bgroup}{\egroup}   But this definition makes \abstracttext expand to \bgroup, which is not what I wanted. I tried to solve the problem by \expandafter,  \newenvironment{customabstract}{\expandafter\gdef\expandafter\abstracttext\bgroup}{\egroup}   but this results in a runaway error.  Is there any way to acheive what I want? Answers that helps me understand the inner workings of TeX (instead of just referring to a custom package) are preferred. JUnit @Test expected annotation not working How can I get a command block? Is there a term for solving a sub-sub problem of a problem so far removed from the main problem the link is not clear? In some situations, trying to solve a problem uncovers another problem. Attempts to fix that uncover yet another. A few more rounds and one can be doing something seemingly completely unrelated to the main problem. Is there an expression for that? Make rigid body collide with hair particles Properly discontinuous action: equivalent definitions Let us define a properly discontinuous action of a group $G$ on a topological space $X$ as an action such that every $x \in X$ has a neighborhood $U$ such that $gU \cap U \neq \emptyset$ implies $g = e$. I would like to prove that this property is equivalent to, having given $G$ the discrete topology and in the $X$ locally compact Hausdorff case, the map $G \times X \rightarrow X \times X$ given by $(g, x) \mapsto (x, gx)$ being proper (i.e. closed and preimage of compact sets is compact) plus the action being free.  I have managed to prove one direction, that is, if the action is proper and free with $G$ having the discrete topology then it is properly discontinuous. I'm having trouble though with the other direction. Here is an attempt: let's denote by $\rho : G \times X \rightarrow X \times X$ the map $\rho(g, x) = (x, gx)$. Suppose $K \subset X \times X$ is compact. We wish to show $\rho^{-1}(K)$ is compact. Let $(g_i, x_i)$ be a net in $\rho^{-1}(K)$. Then $\rho(g_i, x_i) = (x_i, g_i x_i)$ admits a convergent subnet, so passing to it we may assume $x_i \rightarrow x$ and $g_i x_i \rightarrow y$. Essentially we must now find a way to prove $g_i$ converges, but I can't seem to do this. Any hints? Show that no application $f: \mathbb{R}^2 \rightarrow \mathbb{R}$, of $C^k$ class, $k \geq 1$ can be injective How can I proof this:     Show that no application $f: \mathbb{R}^2 \rightarrow \mathbb{R}$, of $C^k$ class, $k \geq 1$ can be injective, i.e., there are $A,B \in \mathbb{R}^2$ such that $A \neq B$ and $f(A) = f(B)$ (Hint: show that given $(a,b) \in \mathbb{R}^2$ in every open neighbourhood of $(a,b)$ there are points $(c,d),(c_1,d_1)$ where ${\partial}_1f(c,d) \neq 0$ or ${\partial}_1f(c_1,d_1) \neq 0$).   The problem is that I have no idea how to use the hint.  Thanks for all your comments. Can I mix monk traditions? I'm wanting to mix archetypes (traditions) for my monk. I'm wanting specifically the 3rd and 17th level feats from Way of the Open Fist and the 6th and 11th level feats from the Way of the Shadows. I know we can't multiclass into the same class to gain both but in the PHB page 79 2nd column "Monastic Traditions" reads "Three traditions of monastic pursuit are in common in the monasteries scattered across the multiverse." I'm fine with that but where I question is "Most monasteries practice one tradition exclusively, but a few honor the three traditions and instruct each monk according to his or her aptitude and interest."   So my question would be can I build a monk that is split like that without homebrewing to much?