Why would I use a robots.txt file?
If I don't want to set any special behavior, is it OK if I don't bother to have a robots.txt file?
Solve Euler Project #9 only mathematically - Pythagorean triplet The "Euler Project" problem 9 () asks to solve:  $a^2$ + $b^2$ = $c^2$ a + b + c = 1000  I find answers solving it with brute-force and programmatically, but is there a way to solve the problem ONLY mathematically? Can someone help, please?  Problem as explained in Project Euler website:  A Pythagorean triplet is a set of three natural numbers, a &lt; b &lt; c, for which,  a^2 + b^2 = c^2 For example, 3^2 + 4^2 = 9 + 16 = 25 = 52.  There exists exactly one Pythagorean triplet for which a + b + c = 1000.  Find the product abc. What is the best prepaid SIM card for data in France? I'm going to travel to Paris in two weeks for 5 days. I'd like to buy a prepaid SIM card for my phone, no calls or SMS needed - only data is sufficient. I've looked through French mobile operators and found nothing really acceptable. For example, in Finland I bought SIM card for €5 with 3GB of data.   So, the question is - what is the best SIM card for me, assuming that 1GB is enough (considering the prices) and that I am actually will be able to use it (I've read that some operators turn on mobile data only after 5 days which is unacceptable for me considering that I'll be there for 5 days only)? I have an Android phone that connects with my computer via MTP. This works fine; I can see and transfer files with Nautilus. However, I often want to use the terminal to move large numbers of files, and I cannot seem to find the device anywhere in the filesystem tree. Nautilus reports the location as mtp://[usb:003,007]/, but it's not under /media or /mnt.  Does anyone know where it is? Multiple Apple Developer Accounts Why doesn't the Windows command prompt window maximize to the full screen size? Anyone know why doesn't the Windows command prompt window maximize to the full screen size?  To the best of my knowledge, even in the new Windows 7 the command prompt window(cmd.exe) doesn't maximize to the full screen size like all other windows. This behavior is quite annoying for me, and I'm sure to many others as well.   Note: The size of the command prompt window can be , but the size remains fixed regardless of the screen size. Objective-C Blocks and variable scope In the Harry Potter universe, wizards and witches have managed to keep Muggles unaware of their existence, across the planet and over many centuries. Up to the timeframe that the novels take place in (the 1990s), I can see how this can be achieved through a combination of discretion and magic, with discretion being the preferred method on occasion (e.g., you don't need magic to slip into Platform 9 3/4 unnoticed, you just need to check that nobody is looking).   Our current world of 2016, however, its a very different place. The UK is (in)famously heavily camera-monitored (). Even more poignantly, a very large (and growing) segment of the population carries an internet-enabled HD camera with them at all times and are willing to use it at a moment's notice (, but it is comedy in part because a more realistic version could happen). It looks like, the moment something magical happens in public, a video of it would be on Youtube/Facebook/Twitter and within minutes.   How does the Ministry of Magic deal with this development? Do they need to create a dedicated corps to monitor social media services and alter records as necessary? Diplomacy Attacking a Territory as they move How to pivot rows into columns MySQL Been looking to pivot rows (progress_check) into columns check 1, check 2 etc... No sum or totals required, just to display the results hopefully... Can anyone help, Thanks Ad Find the probability of an event determined by an inequality on exponential random variables Let X and Y be independent random variables such that $X∼Exp(1)$ and $Y∼Exp(2)$.  Find the probability that $3X+4Y≤5$.  I thought the equation for solving this was the integral from $\int_0^a \int_ 0^{(a-y)} \lambda_1 e^{-\lambda_1 x}\lambda_2 e^{-\lambda_2 y} dx dy$ where $a = 5$, so I first started with the integral from $\int_0^5 \int_0^{(5-y)} 3 \times 1e^{-1x} \times 4 \times 2e^{-2y} dx dy$ and got $23.83828927$ which is much larger than a probability can be. Any help? cmd has wildcard bug? Files in folder:  a.j ab.jp abc.jpg abcd.jpeg   dir command results:  Command       Result (Files shown) ----------    -------------------- dir ?.*       a.j dir ??.*      a.j, ab.jp dir ???.*     a.j, ab.jp, abc.jpg dir ????.*    a.j, ab.jp, abc.jpg, abcd.jpeg   So we can see single ? it means "0 or 1 letter".  Now more dir command results:  Command       Result (Files shown) ----------    -------------------- dir *.?       a.j dir *.??      a.j, ab.jp dir *.???     a.j, ab.jp, abc.jpg, abcd.jpeg --&gt; What is this?! dir *.????    a.j, ab.jp, abc.jpg, abcd.jpeg   In 3rd command why ??? is showing jpeg? Can you explain? Is this bug in cmd? Where does the word "torsion" in algebra come from? Torsion is used to refer to elements of finite order under some binary operation. It doesn't seem to bear any relation to the ordinary everyday use of the word or with its use in differential geometry (which relates back to the ordinary use of the word). So how did it acquire this usage in algebra?  I'm interested to understand the intuition behind why the word "torsion" was chosen for this notion, as well as when it was first used. Bind application to a specific network interface I have tried ForceBindIP, but it has a significant downside - it doesn't affect the children of the application I'm trying to bind, it only affects the application itself. It also can't force an application to always run through a specified interface, it has to be run through forcebindip.exe every time. It becomes a problem with applications like League of Legends where the process tree looks like that:    The launcher runs the patcher, the patcher run the client, etc. I can only affect the parent of all these processes in the tree, so the actual game is not bound to the interface I want, making this whole venture pointless.  Is there a more modern alternative to ForceBindIP for Windows 7? There are many questions similar to this one on this site, but they are mostly old. Maybe there is now a better way to solve this problem?  My current idea is to do the following:   Set up local 3proxy server bound to the desired interface. Run the game through Proxifier or similar software configured to run through that local proxy.   I'm not sure if that will work, but even if it will, it seems like a sub-optimal solution. Do you guys have any better ideas?  Edit: My idea didn't work :(  Edit 2: Basically, what I'm trying to achieve is bind a few applications to a regular interface, while VPN is running. The reason is that I need to connect through VPN most of the time, but some applications (such as games) don't work properly this way, because of higher ping and other issues. "Try and" versus "Try to"? Why can't I capture my first Pokemon? I'm trying to just catch my first Pokemon and I can't for some reason. From what I've read I should be able to see the three basic Pokemon to choose from and catch one but I can't see them.  I can only see three pulsing circles and the app appears to be stuck on map view. I've tried clicking or walking over the circles but nothing happens.   Any suggestion on how to fix this? When ever I need to kill a background process I do ps -e | grep &lt;process_name&gt;  Which prints something like this 1766 ? 00:00:13 conky , Then I use the process ID to kill it like so kill 1766 .   Is there any way I can simplify this ? Make it quicker ? reduce the amount of typing ? Firstly, this is a homework problem so please do not just give an answer away. Hints and suggestions are really all I'm looking for.  I must prove the following using mathematical induction:     For all $n\in\mathbb{Z^+}$, $1+2+2^2+2^3+\cdots+2^n=2^{n+1}-1$.   This is what I have in my proof so far:     Proof: Let $p\left(n\right)$ be $\sum_{j=0}^n 2^j=1+2+2^2+\cdots+2^n=2^{n+1}-1$. Then $P\left(0\right)$ is    \begin{align} \sum\limits_{j=0}^0 2^j=1=2^1-1.\tag{1} \end{align} Hence    $P\left(0\right)$ is true. Next, for some $k\in\mathbb{Z^+}$, assume    $P\left(k\right)$ is true. Then \begin{align}  \sum\limits_{j=0}^{k+1}2^j&amp;=\left(\sum\limits_{j=0}^k  2^j\right)+2^{k+1}\tag{2}\\ &amp;=2^{k+1}-1+2^{k+1}\tag{3} \\ &amp;=2\cdot 2^{k+1}-1\tag{4}\\ &amp;=2^{k+2}-1\tag{5}\\ &amp;=2^{\left(k+1\right)+1}-1.\tag{6} \end{align}   Therefore, $P\left(n\right)$ holds for all $n$.$\;\;\;\;\blacksquare$   Is everything right? My professor went over the methodology in class quite fast (and I had a bit too much coffee that night) and I want to make sure I have it down for tomorrow night's exam. Prove $\frac{|a+b|}{1+|a+b|}<\frac{|a|}{1+|a|}+\frac{|b|}{1+|b|}$. Prove that for every $a, b\in R\setminus\{0\}$ is correct this inequality:  $$\frac{|a+b|}{1+|a+b|}&lt;\frac{|a|}{1+|a|}+\frac{|b|}{1+|b|}.$$ Is there difference in force when the height increases? Stripping seasoning from cast iron After reading , I want to try to re-season a skillet with flaxseed oil; I'm fairly certain I did a terrible job when I seasoned the skillet several years ago. Is it possible to do this with steel wool or vinegar? (I don't have a self-cleaning oven, so that method is out.)