Entering in an accompanied visa but then separating
Can a child enter the UK on an accompanied visa and then leave the country alone?
Probability that an integer number having Poisson distribution is even The probability $P(X=n)$ that an event X takes place $n$ times in a fixed period of time follows the Poisson distribution with parameter $\lambda$ i.e.  $$ P(X = n) = e^{-\lambda} \frac{\lambda ^ n}{n!}$$  I have to evaluate the probability that the event $X$ takes place an even number of times. I know that:   $$ P(X \text{ is even} ) = e^{-\lambda} \cdot \sum_{k=0}^{+\infty} \frac{\lambda^{2k}}{(2k)!}$$  but I can't solve the series.  I guess that I have to use the fact that $e^\lambda = \sum_{n = 0}^{+\infty} \lambda^n/n!$, but I got stuck.  How can I evaluate $P(X \text{ is even})$ (alternative solutions appreciated). How can I upgrade to Java 1.8 on an Amazon Linux Server? I tried sudo yum update but it just keeps java "1.7.0_75". I need 1.8 for it to work with another application but can't figure out how to upgrade it. Do I need to manually install it somehow? There's not much information on this on the internet as far as I can see. Specs:   java version "1.7.0_75" OpenJDK Runtime Environment (amzn-2.5.4.0.53.amzn1-x86_64 u75-b13) OpenJDK 64-Bit Server VM (build 24.75-b04, mixed mode)   When I try update now:     [ec2-________]$ sudo yum update Loaded plugins: priorities, update-motd, upgrade-helper amzn-main/latest                                         | 2.1 kB     00:00 amzn-updates/latest                                      | 2.3 kB     00:00 No packages marked for update   Is there anything else I need to do? Thanks. I've never really understood why math induction is supposed to work.  You have these 3 steps:   Prove true for base case (n=0 or 1 or whatever) Assume true for n=k.  Call this the induction hypothesis. Prove true for n=k+1, somewhere using the induction hypothesis in your proof.   In my experience the proof is usually algebraic, and you just manipulate the problem until you get the induction hypothesis to appear.  If you can do that and it works out, then you say the proof holds.  Here's one I just worked out,  Show $\displaystyle\lim_{x\to\infty} \frac{(\ln x)^n}{x} = 0$  So you go:   Use L'Hospital's rule. $\displaystyle\lim_{x\to\infty} \frac{\ln x}{x} = 0$. Since that's $\displaystyle\lim_{x\to\infty} \frac{1}{x} = 0$. Assume true for $n=k$. $\displaystyle\lim_{x\to\infty} \frac{(\ln x)^k}{x} = 0$. Prove true for $n=k+1$.  You get $\displaystyle\lim_{x\to\infty} \frac{(\ln x)^{k+1}}{x} = 0.$   Use L'Hospital again: $\displaystyle\lim_{x\to\infty} \frac{(k+1)(\ln x)^{k}}{x} = 0$.  Then you see the induction hypothesis appear, and you can say this is equal to $0$.  What I'm not comfortable with is this idea that you can just assume something to be true ($n=k$), then based on that assumption, form a proof for $n=k+1$ case.  I don't see how you can use something you've assumed to be true to prove something else to be true. Python Script returns unintended "None" after execution of a function How do I remove Ubuntu's password requirement? Quoting within $(command substitution) in Bash Showing that Y has a uniform distribution if Y=F(X) where F is the cdf of continuous X Let $X$ be a random variable with a continuous and strictly increasing c.d.f. function $F$ (so that the quantile function $F^{−1}$ is well-deﬁned). Deﬁne a new random variable $Y$ by $Y = F(X)$. Show that $Y$ has a uniform distribution on the interval $[0, 1]$.  My initial thought is that $Y$ is distributed on the interval $[0,1]$ because this is the range of $F$.  But how do you show that it is uniform? How to stop "Monkey Test" and "Time Service" apps When I long-press the "home" button to close all apps, there is an app named "time service" with android symbol and another named "monkey test" that are always open.   How to stop this? Why do the measurements of this object seem erroneous? What theorems can I use to prove this? Strict warning: Only variables should be passed by reference I get the following error:     Strict warning: Only variables should be passed by reference in include() (line 18 of /home/sites/dev/theparce/sites/all/themes/parce/block--block--3.tpl.php).   This is the block code which is causing that error.  if ($user_gallery) {   print render(node_show($user_gallery));  // Line 18   print drupal_render ($user_gallery_edit);  } else {   print drupal_render($user_gallery_new); }   Why do I get that error, even if I get all printed as expected? I've imported several shapefiles which where exported from a Mapinfo .tab. Several  .tab-files are imported resulting in 20+ layers. Afterwards I want to export it to GeoJSON; but I'm reluctant to select each layer and export it manually. Is there a way to merge all the layers into one using QGIS? Minecraft looks like a bad texture pack I am playing Minecraft 1.12 but today the in-game textures look much lower quality than usual. I don't have any of the super secret settings turned on, and I'm unsure how to fix this and get the normal textures back. What causes yogurt in sauces to split? How to prevent it? A lot of my favorite curry recipes have a yogurt based sauce in them, but on a pretty regular basis when I make them, the yogurt ends up splitting into basically curds and whey. What causes that, and how can I prevent it?  As an illustrative example, last night I made a simple tofu curry as follows:   warm evoo in a pan add chopped onion, saute briefly add curry seasonings, allow to warm/season the oil add cubed tofu, toss to coat cook for a while, tossing periodically to lightly brown the cubes turn heat off add plain greek yogurt stir to combine   In the few minutes it took to finish the rest of the meal and start plating, the yogurt had separated so I had a clumpy, lumpy, yogurt soup instead of a smooth creamy sauce. How to do volumetric lighting for a forest scene? I have scene that looks like this:   And I want to add volumetric lighting to it so that light forms a rays of light when it go through the trees like on this example that I found in youtube:   But the problem is that all of these tutorials show how to make this lighting coming from windows, but when I try to replicate it in my forest scene it looks like big ugly fog with cubical shape. Also the light is coming from the back of the camera (as you can see) and there are some spots that needs this special lighting (like places where light goes through trees) and some that don't (like big bright are on the bottom left corner) so I can't just add a giant cube to all of the scene. I think we all understand the necessity of delete when reassigning a dynamically-allocated pointer in order to prevent memory leaks. However, I'm curious, to what extent does the C++ mandate the usage of delete? For example, take the following program  int main() {      int* arr = new int[5];      return 0; }   While for all intents and purposes no leak occurs here (since your program is ending and the OS will clean up all memory once it returns), but does the standard still require -- or recommend -- the usage of delete[] in this case? If not, would there be any other reason why you would delete[] here? What is the danger of running untrusted software as a normal user Sometimes I have to use some propriety softwares which I don't trust or even pre-compiled open source ones which I don't know if they've been compiled as their source are.   Lets say we installed a propriety application in /opt/software, then we run it as a normal user (without sudo, gksudo, etc).   I know when we run a program it is able to connect to the Internet, monitor X, keystrokes, collect user data and so on. It can't change anything important in the system or infect the system, (because of the Linux permissions system). It is possible for program to add some plug-in/extension to a user's browser (Because browser profiles are available in user home directory). After closing the program and rebooting it can't do anything anymore. Wrong because:   Program can add itself to a shell/file/directory which does the autostart process, so it will run at any login.  If we consider the autostart process clean, without rebooting there is a chance that a process of the program is still active. Programs can delete or modify any file in the user home directory (or any other file which a user has write permission to).   So what should we do?   I think the only safe way to run a propriety program is running it as another user. If running the program as another user somehow is not possible then we should change the autostart files permission so only root can change them. then after closing the program a reboot will do the job.   Am I right? Is there anything that I'm missing? What's the difference between eq, eql, equal and equalp, in Common Lisp? What's the difference between eq, eql, equal and equalp, in Common Lisp?  I understand that some of them check types, some of them check across types an all that, but which is which?  When is one better to use than the others? Grub does not show a Windows 8 option after dual boot So, I've successfully dual-booted my Windows 8 machine with Ubuntu 12.04 . However, I still don't have a convenient method of choosing what OS to load at boot time.  After installing Ubuntu, my computer still loads Windows 8 directly. I then added grubx64.efi to the white list of my boot loader. But after that, my machine loads Ubuntu directly without even a shadow of GRUB showing up!  I used boot-repair and I got this paste.ubuntu URL: . After running boot-repair (and re-white listing the grubx64.efi file), GRUB now shows up but without any Windows 8 option!  Lastly, I ran sudo fdisk -l and it gave me this:  WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util fdisk doesn't support GPT. Use GNU Parted.   Disk /dev/sda: 750.2 GB, 750156374016 bytes 255 heads, 63 sectors/track, 91201 cylinders, total 1465149168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x6396389f     Device Boot      Start         End      Blocks   Id  System /dev/sda1               1  1465149167   732574583+  ee  GPT Partition 1 does not start on physical sector boundary.   I'm guessing my problem has something to do with the warning from fdisk above but I don't know what to do with it. How do I proceed now?  Edit  My etc/default/grub is as follows:  # If you change this file, run 'update-grub' afterwards to update # /boot/grub/grub.cfg. # For full documentation of the options in this file, see: #   info -f grub -n 'Simple configuration'  GRUB_DEFAULT=0 #GRUB_HIDDEN_TIMEOUT=0 GRUB_HIDDEN_TIMEOUT_QUIET=true GRUB_TIMEOUT=10 GRUB_DISTRIBUTOR=`lsb_release -i -s 2&gt; /dev/null || echo Debian` GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" GRUB_CMDLINE_LINUX=""  # Uncomment to enable BadRAM filtering, modify to suit your needs # This works with Linux (no patch required) and with any kernel that obtains # the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...) #GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"  # Uncomment to disable graphical terminal (grub-pc only) #GRUB_TERMINAL=console  # The resolution used on graphical terminal # note that you can use only modes which your graphic card supports via VBE # you can see them in real GRUB with the command `vbeinfo' #GRUB_GFXMODE=640x480  # Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux #GRUB_DISABLE_LINUX_UUID=true  # Uncomment to disable generation of recovery mode menu entries #GRUB_DISABLE_RECOVERY="true"  # Uncomment to get a beep at grub start #GRUB_INIT_TUNE="480 440 1"   Also, just for the record,  in installing my dual-boot. The tutorial (which uses, 11.10, I must note), doesn't mention anything about this problem. Is there anything there I shouldn't have done? How do I remove a malformed line from my sources.list?