(Can't boot with UEFI)Can not boot window after installing linux
Unable to boot into Windows after installing Ubuntu, how to fix?
Let $S = \{ax + by: x,y \in \mathbb{Z}\}$  and let $e &gt; 0$ be the smallest element in $S$. Prove that $e \mid a$, and hence prove that $e = \gcd(a,b)$  I'm afraid I can't provide much of my initial working here because I'm at a loss of how to start.  I suppose that to show $e\mid a$ I would have to show that $eg = a$ for some $g \in \mathbb{Z}$. But I have no idea how I would do this. Can anyone help me with this limit problem without L'Hopital rule and Taylor series? $$\lim_{x\rightarrow\ -\infty}\left(-2\frac{\arctan(x)}{\pi}\right)^x$$ I understand that the mechanics and design of a lightsaber aren't that complicated.  Do others besides the Jedi and Sith (or their minions) make or use lightsabers?  And if they don't, why not? Software for measuring internet traffic? I'm interested in finding a free piece of software for Windows XP &amp; 7 that allows us to measure both incoming and outgoing internet traffic, but not traffic between users of the local network.  I live in a shared household with three others, and we're interested to see which of us is using the largest amount of our monthly internet quota. We're all happy to install the necessary software.  Any suggestions? Existence of minimal prime ideal contained in given prime ideal and containing a given subset Let $R$ be a unital commutative ring, $P$ $\subseteq$ $R$ a prime ideal, $X\subseteq P$ a subset. Show there exists a minimal (inclusion minimal) prime ideal contained in $P$ which contains $X$.   My approach: Let $\langle X\rangle$ be the ideal generated by $X$. $P^c$ is a multiplicative set, as $P$ is prime. $\langle X\rangle\subseteq P\subseteq R$ and $P^c\cap\langle X\rangle=\emptyset $ so by Zorn's lemma there exist prime ideal $I_1$ satisfying $\langle X\rangle\subseteq I_1\subseteq P$. As $I_1$ is prime, it's complement is a multiplicative subset which does not intersect $\langle X\rangle$, hence I can find prime ideal $I_2$ satisfying $\langle X\rangle\subseteq I_2 \subseteq I_1$ and so on... I've got an infinite descending chain of prime ideals and I can't be sure that the process will stop.  Hints will be appreciated, thank you.   Edit: Can I conclude that every prime ideal contains a minimal prime ideal? Using trickle to limit the bandwidth of a VirtualBox VM I'm trying to limit the bandwidth of a virtual machine running via VirtualBox.   trickle -d 5 virtualbox doesn't work, I believe because of an issue with child processes (trickle -d 5 sudo apt-get upgrade doesn't work either)  How can I limit the download/upload bandwidth of VirtualBox's VMs? Uniformly convergence of $f_{n+1}(x)= \int^x_0 f_n(t)dt$ Linux Debian codenames I've got a few, quite silly, non-technical questions about giving  to  releases.  Each Debian release has its unique codename, which is (so far) a characters' name from  movies by .  Here is list of all assigned codenames so far:   release 1.1 is  (Buzz Lightyear) - the spaceman, release 1.2 is  - the tyrannosaurus, release 1.3.x is  (Bo Peep) - the girl who took care of the sheep, release 2.0 is  - the piggy bank, release 2.1 is  (Slinky Dog) - the toy dog, release 2.2 is  - Mr. Potato, release 3.0 is  -  the cowboy, release 3.1 is  - the sergeant of the Green Plastic Army Men, release 4.0 is  - the toy blackboard (Etch-a-Sketch), release 5.0 is  - the toy binoculars, release 6.0 is  - the name for the three-eyed aliens, release 7.0 is  - the name of the rubber toy penguin with a red bow tie, release 8.0 is  - the name of the yodelling cowgirl, release 9.0 is  - a purple rubbery octopus toy at , release 10.0 is  - 's pet dachshund (currently ).   List of upcoming major Debian releases' codenames after :   release 11.0 is  - 's horse (currently ), release 12.0 is  - intelligent worm toy with a built-in flashlight.   There are also:   special codename  () which is symbolic link to codename which is currently unstable,  which is symbolic link to codename which is currently stable,  which is symbolic link to codename which is currently testing.   The list of Toy Story  is quite  but at some time, there will be no more characters' names to assign.  My questions are:   What codenames will be assigned if we run out of characters' names? Who decides what is codename of next release (please don't answer ambiguously like: 'community')? How many releases' names are planned ahead?   BTW: Interesting quote from :     The  of using Toy Story names was  by  who   was, at the time, the Debian Project Leader and was working also at   , the company that produced the movies.     by  (: ). I am not from EU. I have Spanish partner and we live in Spain and, because of our official relationship, I have a Spanish family resident permit. We are going to travel to the UK together for tourism. I am confused whether I need an EEA family permit or not.  I will not live there and I'm going to travel with my partner. I was told that I don't need a visa, that showing our civil union document will be sufficent. Is this correct, or do I need a visa to enter the UK?    Thank you so much for your answer. Let me give you more detail.  I hold Turkish citizenship.  My resident card exactly says that Residence Card of a Family Member of a Union Citizen " tarjeta de familiar de la union.   my case is like For example, a non-EEA spouse of a German national living in Germany will usually hold a residence permit issued under German domestic law. Therefore, a United Kingdom EEA family permit is required for travel and entry to the UK , therefore I should consider that I need to EEA Family Permit even if for touristic trip with my partner. Currently using Ubuntu 18.04, and my wireless driver is not being detected.  I've included a .  $ dmesg | grep iwl [    6.212724] Loading modules backported from iwlwifi [    6.212724] iwlwifi-stack-public:master:6988:0d8892f2 [    6.224583] iwlwifi 0000:00:14.3: enabling device (0000 -&gt; 0002) [    6.229811] iwlwifi 0000:00:14.3: Direct firmware load for iwl-dbg-cfg.ini failed with error -2 [    6.230540] iwlwifi 0000:00:14.3: Direct firmware load for iwlwifi-9000-pu-b0-jf-b0-39.ucode failed with error -2 [    6.230547] iwlwifi 0000:00:14.3: Direct firmware load for iwlwifi-9000-pu-b0-jf-b0-38.ucode failed with error -2 [    6.230552] iwlwifi 0000:00:14.3: Direct firmware load for iwlwifi-9000-pu-b0-jf-b0-37.ucode failed with error -2 [    6.230557] iwlwifi 0000:00:14.3: Direct firmware load for iwlwifi-9000-pu-b0-jf-b0-36.ucode failed with error -2 [    6.230562] iwlwifi 0000:00:14.3: Direct firmware load for iwlwifi-9000-pu-b0-jf-b0-35.ucode failed with error -2 [    6.236670] iwlwifi 0000:00:14.3: loaded firmware version 34.0.0 op_mode iwlmvm [    6.248314] iwlwifi 0000:00:14.3: Detected Intel(R) Dual Band Wireless AC 9560, REV=0x318 [    7.264081] iwlwifi 0000:00:14.3: SecBoot CPU1 Status: 0x3, CPU2 Status: 0x2477 [    7.264084] iwlwifi 0000:00:14.3: Failed to start INIT ucode: -110 [    7.276165] iwlwifi 0000:00:14.3: Failed to run INIT ucode: -110   sudo modprobe iwlwifi returns no output. How to remove local (untracked) files from the current Git working tree From an array of objects, extract value of a property as array Sources missing in /etc/apt/sources.list, how do I get them back? I want to try to convert a string to a Guid, but I don't want to rely on catching exceptions (   for performance reasons - exceptions are expensive for usability reasons - the debugger pops up  for design reasons - the expected is not exceptional   In other words the code:  public static Boolean TryStrToGuid(String s, out Guid value) {     try     {         value = new Guid(s);         return true;     }     catch (FormatException)     {         value = Guid.Empty;         return false;     } }   is not suitable.  I would try using RegEx, but since the guid can be parenthesis wrapped, brace wrapped, none wrapped, makes it hard.   Additionally, I thought certain Guid values are invalid(?)    Update 1   had a good idea to catch only FormatException, rather than all. Changed the question's code sample to include suggestion.    Update 2  Why worry about thrown exceptions? Am I really expecting invalid GUIDs all that often?   The answer is yes. That is why I am using TryStrToGuid - I am expecting bad data.  Example 1 . I might be parsing folder names, checking to see if the text after the final . is a GUID.  c:\Program Files c:\Program Files.old c:\Users c:\Users.old c:\UserManager.{CE7F5AA5-6832-43FE-BAE1-80D14CD8F666} c:\Windows c:\Windows.old   Example 2 I might be running a heavily used web-server wants to check the validity of some posted back data. I don't want invalid data tying up resources 2-3 orders of magnitude higher than it needs to be.  Example 3 I might be parsing a search expression entered by a user.     If they enter GUID's I want to process them specially (such as specifically searching for that object, or highlight and format that specific search term in the response text.)    Update 3 - Performance benchmarks  Test converting 10,000 good Guids, and 10,000 bad Guids.  Catch FormatException:    10,000 good:     63,668 ticks    10,000 bad:   6,435,609 ticks  Regex Pre-Screen with try-catch:    10,000 good:    637,633 ticks    10,000 bad:     717,894 ticks  COM Interop CLSIDFromString    10,000 good:    126,120 ticks    10,000 bad:      23,134 ticks   p.s. I shouldn't have to justify a question. Particle speed and density I am using a Particle system to simulate falling dust / debris. The particle start and end fairly quickly. They should look like a short burst of falling dust.  I cant figure out how to get the particles to fall at slightly different speeds.  The particles should be falling downwards with very little Brownian motion.  The fact that the particles are falling at the same speed makes them look odd / too uniform (almost like a static image of some particles which is moving down rather than individual particles.  Also the particles end at a set frame so I get a uniform trailing edge (as below).   A bit of air drag helps a bit but not much.  Question 1. how to vary the downward speed of the particles?  Question2. Can the density of particles be animated so I can brake up the distribution?  Thanks Oliver What happens to waves when they hit smaller apertures than their wavelenghts? I was wondering this for quite a long time now. Let's say you have a water wave (like ripples, not the ones you see during tsunamis) with wavelength 10 m. Imagine you put a boundary with an opening of 1 m. Will diffraction be observed? According to my research, no. But, then, what would be seen? Need help identifying short story about retired military colonel who fought war at end of time I read this story in an anthology in the eighties or early nineties.  It was about an old man who lived outside a western-like town, though that might have just been how I imagined it.  He goes to town and some ex-military thugs are there causing problems.  Flaunting some odd interdimensional military tech of some sort.  He doesn't want to intervene as doing so would be bad but in the end he must.     By intervening, his military identity is revealed and that causes him (some paradox or causality law) to have to go back and fight the war again.   The war is at the end of time or the universe.  The man is maybe a colonel of the sky something... Not much to go on; I have been searching my collection and wracking my brain for years trying to recall the story. What is the difference between "likelihood" and "probability"? The  claims that likelihood and probability are distinct concepts.     In non-technical parlance, "likelihood" is usually a synonym for "probability," but in statistical usage there is a clear distinction in perspective: the number that is the probability of some observed outcomes given a set of parameter values is regarded as the likelihood of the set of parameter values given the observed outcomes.    Can someone give a more down-to-earth description of what this means?  In addition, some examples of how "probability" and "likelihood" disagree would be nice. How to display quick-updating images without large memory allocation? gnome-software on Ubuntu 16.04 doesn't work