I have read many people that wrote about this but nothing helped so far. I never get any email notification about answers or comments to my questions although my settings are set up to receive them. What am I missing?

Not getting email alerts on answers on my questions on stackoverflow.com   Used to get it earlier (>1 month back), but not getting alerts in recent times Email field in profile is filled  In prefs, "I'd like email notifications of activity on questions I've asked" is ticked.   What is missing?  Is it possible that signing up on another Stack Exchange community (say, Server Fault), on which by default, "I'd like email notifications of activity on questions I've asked" is unchecked affects same preference on stackoverflow.com? If so, it is a bug.


Good Day,  I want to give Ubuntu more HDD space so I tried to create a new partition then merge it with my Ubuntu's. Windows is unable to create more that 5 partitions I decided to uninstall then re-install Ubuntu.  I used a recovery disk to uninstall Ubuntu. I went into the command prompt and ran "bootrec /fixboot" the following message appeared "The volume does not contain a recognized file system. Please make sure that all the required file system drivers are loaded and that the volume is not corrupted." "Bootrec /fixmbr" ran without any problems.  When I turned on the computer it booted into Windows 7  Question - Do I still need to run "bootrec /fixboot" or can I delete the Ubuntu Partition and run Windows 7 without any problems?

I have a Win/Ubuntu 11.10 dual-boot setup, where I am running the OSes on separate partitions of my laptop HDD. I assume the best method of uninstalling is 'simply' a matter of deleting the Ubuntu partitions -once I've made sure control is given to the Windows bootloader instead of grub after POST.  The question is: How do I do that?  Stuff I've tried:  I tried the boot-repair CD (), but that was a bit beyond my abilities to figure out if I could do it with that tool :/.  I also tried EasyBCD (). It couldn't identify my ext3 partitions, let alone change the bootloader.  Lastly, I tried installing startup-manager in Ubuntu, and using that to set the Win7 bootloader as default. But upon restart, it still loads grub.


Does there exist a continuous function $f :\mathbb{R} \rightarrow \mathbb{R}$ such that $f \circ f(x) = -x$ for all $x$?  My feeling is that there isn't, but I don't know how to go about proving this.

I've been perusing the internet looking for interesting problems to solve. I found the following problem and have been going at it for the past 30 minutes with no success:     Find a function $f: \mathbb{R} \to \mathbb{R}$ satisfying $f(f(x)) = -x$ for all $x \in \mathbb{R}$.   I am also wondering, can we find $f$ so that is continuous?  I was thinking of letting $f$ be a periodic function, and adding half the period to x each time. I had no success with this, and am now thinking that such a function does not exist.  Source:


I was trying to learn how to use yield inside functions, but every time I added yield to the function I couldn't call it. I followed a tutorial and made this def infinite_sequence():     num = 0     while True:       yield num       num += 1  but when I called infinite_sequence()  it didn't work. It did work work when I took out yield. Stopped working when I added return. Started working again when took return. Why does this happen? Do you need to call on functions differently when you add in yield or return? Is it just repl?

What is the use of the yield keyword in Python? What does it do? For example, I'm trying to understand this code1: def _get_child_candidates(self, distance, min_dist, max_dist):     if self._leftchild and distance - max_dist < self._median:         yield self._leftchild     if self._rightchild and distance + max_dist >= self._median:         yield self._rightchild    And this is the caller: result, candidates = [], [self] while candidates:     node = candidates.pop()     distance = node._get_dist(obj)     if distance <= max_dist and distance >= min_dist:         result.extend(node._values)     candidates.extend(node._get_child_candidates(distance, min_dist, max_dist)) return result  What happens when the method _get_child_candidates is called? Is a list returned? A single element? Is it called again? When will subsequent calls stop?   1. This piece of code was written by Jochen Schulz (jrschulz), who made a great Python library for metric spaces. This is the link to the complete source: [Module mspace][1].


I got this error while installing system updates. It looks like it might be due to dependency issues. Updated with apt-get and used -f install. I got this error:   E: The package linux-headers-4.4.0-65 needs to be reinstalled, but I can't find an archive for it.    Could anyone suggest how to resolve this issue?

Running Synaptic I get the following error message:  E: The package hl1440lpr needs to be reinstalled, but I can't find an archive for it. E: Internal error opening cache (1). Please report.   Upon accepting the message, Synaptic quits.


Let $X$ be a Banach space and let $A\colon X\to X^*$ be a linear operator satisfying $$(Ax)(x)\geq 0\quad\forall x\in X.$$ Show that $A\in L(X,X^*)$.  Here, $L(X,X^*)$ stands for the set of bounded linear transformations from $X$ to $X^*$ (the set of bounded linear functionals on $X$). By considering the identity $(A(x+y))(x+y) \geq 0$ and $(A(x-y))(x-y) \geq 0$ (I think) I was able to show that $A$ was bounded if and only if the expression $(Ax)(x)$ was bounded (across $|x| \leq 1$). But this doesn't seem to help much as I don't know how to show this expression is bounded. Does anyone have any ideas of how I could solve this one? EDIT: I asked this question on Reddit as well and someone proposed the following counter example that I cannot find fault in.  Let bₙ, n ∈ ℕ, be a countable set of linear independent vectors and bⁿ their duals. Complete bₙ to an algebraic basis of X. Set Abₙ = n⋅bⁿ and 0 on the other basis vectors  It'd be nice if someone could help explain what's wrong with this logic (or confirm that this question is in fact faulty as stated).

Let X be a Banach space and suppose $T:X \rightarrow X^*$ is linear and has the property that whenever $f=T(x)$ then $f(x)\geq 0$. Prove T is bounded.  The book gives a hint: using closed graph theorem.  I stucked at proving $|T(x_n)-T(x)|=\sup_{\|y\|\leq1}|f_{x_n}(y)-f_x(y)|\rightarrow0$.  Any suggestion is appriciated.


Some annoying websites (like Stack Exchange) contain dialogs.   It's annoying.  So how can I permanently disable these dialogs on Chrome?

Sorry if it's been asked. I've already found several solutions that aren't working. Not sure what I'm doing wrong.   I don't want to disable all javascript, only Javascript alert boxes. The ones that pop up and force you to click OK or X to close them.  I've found user scripts that claim to do this (example:  ). I've put chrome on the dev channel, start chrome with the --enable-user-scripts switch, the script shows up as installed.  But I still get the alert boxes.  An example alert box that isn't getting disabled is at  - put in any garbage word into the word validator on the right sidebar. You get a popup telling you it's not a word.


What is the best way to punctuate interrupted dialogue? I have seen it done like this, but I am not sure if it is correct.  "In my opinion the best w--"  "Nobody is interested in your opinion," Fred cut in.  I think that this is called an em dash and that some softwares will put the two hyphens together to make a single, long em dash.  If this is the proper way to signify interrupted speech, is it OK if the software does not join the hyphens into a single em dash. Are two hyphens OK?

I generally know how to use a hyphen, but when should I use an en-dash (–) instead of an em-dash, or when should I use a hyphen (-) instead of an em-dash (—)?


I have a question about Java:  public class Tester {    private int[] testArray = {3, 4, 5};    public void increment(int n) {         n++;   }   public void firstTestMethod() {        for(int i = 0; i < testArray.length; i++) {             increment(testArray[i]);             System.out.print(testArray[i] + " ");        }   }  }   The output produced when invoking firstTestMethod for a Tester object is 3 4 5. Could someone please help explain why? Thank you!    Hi all,  Could anyone take a look at this other problem? The correct answer is C, but I just don't understand! The link to the picture is below.  Thanks in advance!

I always thought Java uses pass-by-reference. However, I've seen a couple of blog posts (for example, ) that claim that it isn't (the blog post says that Java uses pass-by-value). I don't think I understand the distinction they're making. What is the explanation?


Usually I have trouble acquiring items, but in 1.11 with a mending fishing rod I'm starting to have a problem I've never had before... too much junk.  So I built a simple incinerator, consisting of a single lava block hidden in my stone floor, with a dropper immediately above it to hide it. This was inset in the wall, and had a button to activate. A little tedious collecting all 80 saddles and 2000 boots (I exaggerate only slightly), put them in, and soon things are back to normal.  That is, until the spontaneous fires occurred. I don't use very many flammable blocks, so it was more shocking than harming, but I wasn't aware that air blocks above lava can catch fire spontaneously even if covered.  How deep do I have to put the lava so that the stone floor doesn't burst into flames? I've got at least 5 or 6 depth that I can use for this.

It seems that containing lava in solid glass, stone and iron blocks may not be sufficient to prevent wool from burning, even if the lava is completely encased.         After some delay, it seems that fire will jump onto the wool above the iron.   Are solid blocks more effective than airspace, or not? If so, Does it matter whether the corner block is filled in? What are the exact rules on distance that I need, and how can I prevent flammable blocks from being eliminated by nearby lava? Bonus: Does a flowing lava block behave differently than a lava source block when it comes to fire creation?


I was refused a French visa and now I got a refusal from the Latvian Embassy. I do not understand the reason:      The information submitted regarding justification for the purpose and conditions of the intended stay was not reliable.    When I apply to the Embassy of Portugal, how do I explain? Is the previous refusal letter necessary in a new file or not?

Schengen refusal formulae can be difficult to understand sometimes.  Sometimes an applicant receives a refusal with:       Justification for the purpose and conditions of the intended stay was not reliable.     often accompanied by:       Your intention to leave the territory of the Member States before the expiry of the visa applied for could not be ascertained.   What is meant by this refusal reason?  What are they trying to say?


I just saw this symbol in an article of 1990 and was curious about how to display it in latex, but haven't found any answers after googling.  Does anybody know that or tell me it is actually rarely used nowadays?    It's at the end of the paragraph. Thanks a lot!

I know what my symbol or character looks like, but I don't know what the command is or which math alphabet it came from. How do I go about finding this out?


When I download updates or installing new software I get these warnings that I have no public keys. This just appeared one day and I didn't remove/add something to create this.     Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 16126D3A3E5C1192   I have tried: sudo apt-key update and it worked for some keys, but others are still missing, I need to add them.  I need help with adding the new keys and the address to all the keys. Those that aren't in Ubuntu and launchpad.

I added some extra repositories with the Software Sources program. But when I reload the package database, I get an error like the following:     W: GPG error:  trusty InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8BAF9A6F   I know I can fix it using apt-key in a terminal, according to the official Ubuntu documentation. But I would have liked to do it graphically. Is there a way to do this without using a terminal?


My 2 questions were closed. Just closed. I disagree with simply closing because I'm ready to edit my question until it is accepted. If I would not do this I would agree with closure. Just closing someone's question is the simplest operation in the world, but explaining and helping a person to improve his question is cumbersome. So, some people do the easy stuff.    My recommendation to not allow people to close a question unless they make an effort to help. When help is given, but a person who asked a question has no response to it, I think then it's quite fair to be closed.    When a question is open and is improved, then many newbies can benefit from the answer posted. When it's simply closed, that is only garbage in the forum.    Let's help each other, my friends!

Questions can be closed or marked as duplicates.  What does it mean for a question to be "closed"? What does it mean for a question to be marked as a "duplicate"? Who can close a question? What are the reasons for closing a question ? Is closure the end of the road for a question? When are closed questions eligible for deletion?   Related        For more information, see "" in the .


Recently a user asked a question on Meta asking about his deleted account (I won't draw attention to him or his question unless it is really necessary but shouldn't be hard to find - at least until the question gets deleted1 as I don't know if it is relevant to this question).  However, while looking at his account, it appears as if he received the association bonus on all of his accounts, including the new Stack Overflow account he just created, but does not have any account with >200 rep.    The most likely scenario is that the deleted account had more than 200 rep and triggered  the association bonus, but that leads to 2 questions:   Why did his previously associated accounts retain the association bonus? Why did he get an association bonus on his brand new account?   Is this a  or ?  1 - The post in question was deleted by the OP several hours ago but before then the account was confirmed by a mod to be deleted due violations of a sock puppety nature (which I think everyone suspected at the time).  Given that the account in question was a sock puppet, I think it highlights an important reason for removing the association bonus when the account that triggered the bonus is deleted.  Theoretically, as long as he keeps getting the association bonus, he can go to any site and already have more than enough privileges to do damage.

I recently hit 200 rep on Stack Overflow and got a big 100 rep bonus. Most know this as the 'association bonus'.  If I offer a bounty of 50 points and thereby lessen my 'base' score, do I lose that association bonus?  What if I offer a 150 point bounty and then work my way back to 200?


I'm trying to find questions that I can answer. So I reviewed advanced search help page, and I found answers:0 which helps me avoid questions that already have answers and locked:false to avoid locked questions.  What I would like to do is limit questions to those that have one of the tags in a list. For example, if I search for [python] [php], then I only get questions that have both tags. How do I get those that have either one?

How do I search for questions with specific tags?       For more information about searching, see "" in the .


I have two tables like this:-  Tablea ------- id|Comp_name| 1 |abc  |  Tableb -------- ids|id|Comp_name| 2  |1 |def|    I'm trying to inner join these two table into one with query like this  SELECT * FROM tablea  INNER JOIN tableb ON tablea.id=tableb.id   The result is like this   id|Comp_name|ids|Comp_name| 1 |abc      |2  |def|   . How To separate Comp_name value into php ? I tried code like this but fail:-  foreach($query->result() as $row){ echo '<tr class="'.$class.'">          <td>             '.$row->Tablea.Comp_name.'          </td>          <td>             '.$row->Tablea.Comp_name.'          </td>

I have two tables in my database:  NEWS table with columns:   id - the news id  user - the user id of the author)   USERS table with columns:   id - the user id   I want to execute this SQL:   SELECT * FROM news JOIN users ON news.user = user.id    When I get the results in PHP I would like to get associative array and get column names by $row['column-name']. How do I get the news ID and the user ID, having the same column name?


I own a Toshiba Qosmio F60-11H, with features listed here  to which I add that the card integrated DVB-T is produced by Yuan High Tech-although reported as Toshiba. I would like to install on the same computer Windows 7 HP 64bit by default, Ubuntu 12.04 and OpenSuse 12.2, with the help of Super Grub. I would like to have or know of a guide indication to proceed with this triple-boot system, keeping in mind that OpenSuse, rpm distro to my liking in KDE, has the characteristic of being a bit 'pushy and that, therefore, the ignition phase, when offers a choice of OS to boot, it appears as if it were present in several versions but even if it is always the same. Thanks

In my laptop I currently have Windows 7 and Ubuntu 12.04 in dual-boot.  I tried the newest version of WattOS (based in Ubuntu) today from a live-USB,  and decided to install it to my hard drive, to use whenever I am completely dependent on battery energy.  However I don't want to create any conflicts and boot problems, specially because my DVD drive is not working and thus I am unable to use Windows 7 DVD to repair MBR.  What is the safest way to install a second Linux distribution (in this case Watt OS) and update Grub Menu, without major trouble?


Is it acceptable to modify a question (adding details and conditions to obtain the situation) which seems similar to the problem one encounter rather than creating a new question which might be marked as duplicate? As I encountered the same situation  but my working environment is different (system and versions) and I have applied all solutions provided to this question but that didn't help.  Should I post a new question or modify by adding details of my environment?  Can I ask a question by commenting on that post?  If I ask the question how can it be different, as I asked this question is getting down votes yet it is different from ?

Suppose you had a question, and you really want a good answer that would solve your problem, but noticed it was already asked by someone else. Now, a lot of answers had been posted and upvoted, and maybe one was accepted. However, none of the answers solved your problem. The system does not promote the question very much because it is not considered "unanswered", and a lot of users who would otherwise bother to give a correct answer will probably skip the question completely as there are already many highly-voted answers.  Now, what should you do in this case?  One idea is to ask a new, completely identical question, but now you're in control to decide when it is answered. But would that go against SE policy?


I have a PPA with latest Qt Creator and I use another PPA with latest Qt5 that needed for QtC compile and run.  Is it possible for end-user simple add my PPA and automatically add dependment PPA? Or must I notify user that another PPA is used and he must add it manually? What is heppens when dependment PPA will be changed?

I have a package (fcl) in my PPA  in my launchpad PPA and it depends on another package (libccd) which is in another PPA ppa:imnmfotmal/libccd. fcl has both build and run dependency in libccd. So i added libccd as a PPA dependency in launchpad and both are successfully build. but when i am trying to install fcl package after adding the fcl PPA, its throwing an error Reading package lists... Done Building dependency tree        Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  fcl : Depends: libccd but it is not installable E: Unable to correct problems, you have held broken packages.  but its successfully getting installed after adding the libccd PPA also. I want fcl to install libccd automatically without adding its PPA. how can i achieve it ?? Output of apt-cache policy fcl fcl:   Installed: (none)   Candidate: 1.0-0ppa5   Version table:      1.0-0ppa5 0         500 http://ppa.launchpad.net/imnmfotmal/fcl/ubuntu/ trusty/main amd64 Packages


I want to refresh the CSS in my browser when I save a change to the CSS file with BBEdit.   There is a browser plugin called live reload which does this, but it crashes when chrome inspector is open. There are js codes you can save as bookmarks that are supposed to work when you click them, but none of these work for me locally.   Can BBEdit fresh a page or just refresh a pages's CSS when a CSS file is saved? Ideally id work with Chrome, but if BBEdit provides its own browser (as Espresso does) this would also work ok.

Are there any add-ons that will cause a browser to automatically refresh a page when a particular file changes on disk?


Whenn I run sh /opt/script/cypress.sh  Everything works, the script changes directory and executes a command to open another script. But when I have my crontab like this 1 * * * * /opt/script/cypress.sh  It doesn't work. I edited the crontab with "crontab -e" and tested if it works with a touch command The cypress.sh looks like: #!/bin/sh cd "/opt/script" | ./cypress > /opt/script/log;  And the cypress file looks like: cd "/opt/Website Testing/" npx cypress run --record --key *  I replaced the record key with "*" for this post

I have a script that checks to see if port 4000 is open and listening, if it is return true, else start a service that also outputs a logfile. The script runs fine if I execute it as a user, but if I add it as a cron it doesn't run. I'm logged in as root, the script is owned by root, the script has executable permissions, and I am running crontab -e as root.   #!/bin/bash if lsof -Pi :4000 -sTCP:LISTEN -t >/dev/null ; then     return 1 else     seoserver -p 4000 start > /var/www/vhosts/domain.com/httpdocs/seoserver.log & fi   And here is my cron  */5     *       *       *       *       /usr/bin/seoStart


On a system with nvme memory, I installed (K)ubuntu 19.04. The installer did not detect the preinstalled Windows 10 installation and only offered a complete wipe. So I prepared the disk with parted and did a manual install.  Disklabel type: gpt  Device             Start       End   Sectors   Size Type /dev/nvme0n1p1      2048   1026047   1024000   500M EFI System /dev/nvme0n1p2   1026048   1288191    262144   128M Microsoft reserved /dev/nvme0n1p3   1288192 283981890 282693699 134,8G Microsoft basic data /dev/nvme0n1p4 283983872 285702143   1718272   839M Windows recovery environment /dev/nvme0n1p5 285702144 498561023 212858880 101,5G EFI System /dev/nvme0n1p6 498561024 500117503   1556480   760M Linux swap   However, update-grub can't detect the windows installation (even when the windows partition is mounted) and I can't boot into Windows any more.  I've tried boot-repair with different options, but no avail. Here is my updated bootinfo generated by boot-repair:   Questions:   Why is Windows not in the GRUB menu? How can I revive Windows 10?   How come the installer doesn't offer the "install alongside windows" option? Why is boot-repair failing? Can it handle nvme media? Is it outdated?   It doesn't seem these questions are answered in

I installed Windows on my computer, followed by an installation of Ubuntu. However, now I'm unable to boot into my Windows install.  What can I do to fix this?


Proof.  Let $T$ be a bounded linear operator.  Then $$\|T\|=\sup_{x\neq 0}\frac{\|Tx\|}{\|x\|}$$  So $\|T\| \geq \frac{\|Tx\|}{\|x\|}$, that is, $\|T\|\cdot\|x\|\geq \|Tx\|$.  I'm not understand if I let $M=\|T\|$. Is this proof correct?

From the  on the dual of a norm:  $X$ and $Y$ are normed spaces, and we associate with each $f\in L(X,Y)$ (the space of bounded linear operators from $X$ to $Y$) the number $$\|f\| = \sup\{|f(x)|:x\in X, \|x\| \leq 1\}.$$  At some point in the proof that $L(X,Y)$ is bounded, it seems like they use the inequality $$\|fx\| \leq \|f\|\cdot\|x\|,$$ where $\|x\|\leq 1$.  I can't see why this should holds.   $\|f|\|$ is the supremum of what $|f(x)|$ can be, given that $\|x\|\leq 1$. So, given that $\|x\| \leq 1$, $|fx|$ should be bounded by $\|f\|$. But why should it be bounded by $\|f\|\cdot\|x\|$?


thank u for taking time to read my question. It is probably a beginner level question, but I did a lot of search without finding an answer.   I am starting to learn React, and at the very beginning of the ,  it requires a running server.  I have Apache installed and running in my Ubuntu System.  Also, I put all needed example files from the tutorial including the "server.php" in my local "/var/www/react-tutorial-master" folder.  And finally, in the terminal, I entered to the folder above, and executed "php server.php" as the tutorial says.  BUT, the terminal tells me that      "PHP Parse error:  syntax error, unexpected '[' in   /var/www/react-tutorial-master/server.php on line 37 "   I didn't do any mdodification to the file. And I am not familiar with PHP, but I don't think the example "server.php" has any syntax error.  So propably I am missing something, could you please tell me what I am missing.  Here is a  that describes my problem.  Thanks a lot!  The "server.php" looks like this:  <?php /**  * This file provided by Facebook is for non-commercial testing and evaluation  * purposes only. Facebook reserves all rights not expressly granted.  *  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL  * FACEBOOK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */ $scriptInvokedFromCli =     isset($_SERVER['argv'][0]) && $_SERVER['argv'][0] === 'server.php';  if($scriptInvokedFromCli) {     $port = getenv('PORT');     if (empty($port)) {         $port = "3000";     }      echo 'starting server on port '. $port . PHP_EOL;     exec('php -S localhost:'. $port . ' -t public server.php'); } else {     return routeRequest(); }  function routeRequest() {     $comments = file_get_contents('comments.json');     $uri = $_SERVER['REQUEST_URI'];     if ($uri == '/') {         echo file_get_contents('./public/index.html');     } elseif (preg_match('/\/api\/comments(\?.*)?/', $uri)) {         if($_SERVER['REQUEST_METHOD'] === 'POST') {             $commentsDecoded = json_decode($comments, true);             $commentsDecoded[] = [                 'id'      => round(microtime(true) * 1000),                 'author'  => $_POST['author'],                 'text'    => $_POST['text']             ];              $comments = json_encode($commentsDecoded, JSON_PRETTY_PRINT);             file_put_contents('comments.json', $comments);         }         header('Content-Type: application/json');         header('Cache-Control: no-cache');         header('Access-Control-Allow-Origin: *');         echo $comments;     } else {         return false;     } }   Line 37 is      $commentsDecoded[] = [

This is something I've pseudo-solved many times and have never quite found a solution for.  The problem is to come up with a way to generate N colors, that are as distinguishable as possible where N is a parameter.


The equation in question is: P(A, B) = P(A | B) * P(B), and P(A,B) = P(A) * P(B). You can see in the image the portion of A ∩ B.   In , you can see that the A ∩ B portion is empty space. So according to the image, P(A ∩ B) = 0, P(A | B) = 0, which is clearly wrong.  The way I intuitively visualize the diagram is: each pixel is a event. If a pixel is in circle A, it belongs to A. If a pixel is in both A and B, it is in A ∩ B. This interpretation is clearly wrong.   So how to interpret the Vein diagram correctly? How to visualize P(A ∩ B), P(A | B) in the case where A is independent of B ?  If possible, could anyone draw an image ?  Thank you for your help.

Are both the Venn diagram's (i and ii) showing dependent properties (showing that A and B are dependent on one another), I am told that the quartered one is independent (Venn diagram i), however I do not see any difference between the 2 diagram's. Surely P(A|B) (probability of B given A), will come out to be the same in both diagrams. This is because we are constrained to A and AB (highlighted red in Venn diagrams) as we know the outcome will be either AA or AB. Further, the ratio of N(AB) to N(A) will give us our probability P(A|B), which can be seen to lie in both diagrams to be in the region A and AB.  I know that if P(A|B) = P(B) , we have independent events, however how can we deduce if the Venn diagrams are showing independent events or not. Thanks


I would like to "save" a program into my spartan 3AN, I explain :   Currently, I can program my FPGA and use it but when I shut down the board and power it, the program isn't there yet and I've to program my chip again...  Can someone tell me the solution to save my program somewhere in the FPGA?  Thank you !

Considering I made an architecture to do some specific thing, wrote in vhdl, for example.  Can I 'burn' it in a fpga chip, forever? Or how should I do it, protecting the intelectual property knowing the fact it can be read from the serial flash memory?


I've modified \item to insert a \vfill after each occurrence to space out bulleted lists on slides so they do not cluster in the center following this . However, to balance out my vertical spacing, I have to include a \vfill at the end of each slide.  \begin{frame}     \begin{itemize}         \item foo         \item bar         \item baz     \end{itemize} \end{frame}   I'd like to avoid this repeated effort by modifying the frame environment to automatically include a \vfill before the \end{frame}:  \begin{frame}     \begin{itemize}         \item foo         \item bar         \item baz     \end{itemize} \vfill % I want this automatically inserted \end{frame}   Thus, I need to run a command before the end of each frame. The top answer to this  details how to use  to tap into the low level commands in  to add arbitrary TeX code to the end of each slide. However, I've tried modifying the provided code and it results in placing a test string after the frame environment ends, resulting in a blank slide after each slide with the test string at the top, or before, with a blank slide before each slide with the test string at the top. Needless to say since my test string is appearing on slides by itself, when I replace it with \vfill, my the items on my slides are not spaced out like they should be.  I don't understand beamerbaseframe.sty well enough to know which command I should be patching to achieve my desired outcome. Where should I be looking to patch to add a command directly before the end of every frame?  MWE with my attempt at solving this and demonstrating the spacing I'd like to achieve:  \documentclass{beamer}  \usepackage{etoolbox}  \makeatletter \patchcmd{\beamer@doseveralframes}% <cmd> {\beamer@reseteecodes}% <search> {\beamer@reseteecodes\textbf{aaa}}% <replace> {}{}% <success><failure> \makeatother  \let\olditem\item \renewcommand{\item}{%     \olditem\vfill}  \begin{document}  \begin{frame}     \begin{itemize}         \item foo         \item bar         \item baz     \end{itemize} \end{frame}  \begin{frame} % this slide is spaced how I want     \begin{itemize}         \item foo         \item bar         \item baz     \end{itemize} \vfill \end{frame}  \end{document}

I use \setlength\itemsep{\fill} to vertically stretch items in an itemize environment. This works fine if I don't have a sub-list:  However, if there is a sub-list, the item following the sub-list would not be stretched. As you can see in the screenshot below, the space between the first two level-1 items is smaller than the space between the last two.  Question How do I fix this issue in a way that does not require setting a fixed length for \itemsep (e.g. 10pt) or manually adding \vfill before every level-1 \item? MWE \documentclass{beamer} \begin{document} \begin{frame}{Title}   \begin{itemize}     \setlength\itemsep{\fill}     \item item      \begin{itemize}       \item subitem      \end{itemize}     \item item     \item item   \end{itemize} \end{frame} \end{document}


NOTE : By perpendicular component of $\vec{F}$, I mean a vector which is a component of $\vec{F}$, but perpendicular to it.  In the image above, the red vectors are a possible set of rectangular components of $\vec{F}$, and blue vector is the sine component of cos component of $\vec{F}$, ie,  perpendicular component of $\vec{F}$. Now, logically, the perpendicular component of $\vec{F}$ should be zero, since its projection is zero. But if we consider the image above, the Perpendicular component, $|\vec{F}|\cos\theta\sin\theta$, is not zero. What is the cause of this discrepancy, and how to take components properly?

Suppose there's a force $F$ of magnitude 10 newtons in the direction of positive y-axis acting on a particle A. I know that the particle would not experience any force in the positive x-direction because,  component of force $F$ in the positive x-direction $=|F|cos90°=0$.   But if we first take the component of $F$ at an angle of 45° to the positive y-axis, it is,   $|F|cos45°=\frac{10}{\sqrt2}\text N$.   If we now consider this a vector (can we? that is the main question), we can find its component in the positive x-direction (it makes an angle of 45° with the positive x-axis) ,   $\frac{10}{\sqrt2}\times cos45°=5\text N$. According to this result, the particle should experience a force of 5 newtons in the positive x-direction, which is impossible. I want to know what all is wrong in the above reasoning. Thanks!


I have the following function inside a BASH script (running under Ubuntu 12.x), which would copy over a file with spaces inside the file name. It's not working. I've tried many different combinations, with "', with \", etc. How do I get this to work? Thanks!  function copy_docs() {     source_directory=/mnt/someplace     release_directory=/doc/someotherplace      cp ${source_directory}/"Some file with spaces.txt" ${release_directory}/  }   This is what I'm getting as output (from nearly all permutations):  cp: cannot stat `/mnt/someplace/some': No such file or directory cp: cannot stat `file': No such file or directory cp: cannot stat `with': No such file or directory cp: cannot stat `spaces': No such file or directory

Or, an introductory guide to robust filename handling and other string passing in shell scripts.  I wrote a shell script which works well most of the time. But it chokes on some inputs (e.g. on some file names).  I encountered a problem such as the following:   I have a file name containing a space hello world, and it was treated as two separate files hello and world. I have an input line with two consecutive spaces and they shrank to one in the input. Leading and trailing whitespace disappears from input lines. Sometimes, when the input contains one of the characters \[*?, they are replaced by some text which is is actually the name of files. There is an apostrophe ' (or a double quote ") in the input and things got weird after that point. There is a backslash in the input (or: I am using Cygwin and some of my file names have Windows-style \ separators).   What is going on and how do I fix it?


My Python files opens in  instead of Python. Is there a way to fix this?  I have tried to allow them to execute in the properties setting, but that didn't work. I can open them in the terminal, but not in the "usual" way.

When I double-click on a script in Nautilus to run it, the script just opens in my text editor with no option to run it. Using Nautilus, how do I run executable text files and/or scripts?


Let $U$ be a countably complete free ultrafilter over S. Prove that there is an uncountable cardinal $\kappa, \kappa \le |S|$ with a $\kappa$-complete free ultrafilter over $\kappa$.   Is the following attempt correct:  I say that $\kappa$ is the smallest cardinal such that the intersection of $\kappa$ many members of $U$ is not a member of $U$ and assume a sequence {$A_{\alpha} : \alpha \in \kappa$} and $B_{\beta}$= $\bigcap$ {$A_{\alpha} : \alpha \lt \beta$}\ $A_{\beta}$. Now I need to prove that there is an ultrafilter that contains $B$ and I am stuck there.

We know that a cardinal $k > \omega$ is measurable if there is a measure function $\mu :2^k\mapsto \{0, 1\}$  that satisfies the following 3 conditions:  1.$&ltk$ -additive: for every set I of indices with card(I) < k, and for every family of pairwise disjoint sets $z_i$, where $i\in I$, we have $\displaystyle \mu(\bigcup_{i\in I} z_i)=\sum_{i\in I} \mu(z_i)$.  2.$\mu(k)=1$  3.$\mu (s)=0$ for every singleton.  Ok, now what if there exists a cardinal $k>\omega$, and a measure function $\mu :2^k\mapsto \{0, 1\}$ that satisfies conditions 2 and 3 above, but is only $ &lt\omega_1$ -additive ? How can we show that this weaker condition still implies the existence of a measurable cardinal?  Thanks a lot!


I have a large shapefile with 400k census sections in a table called census_poly. I want to return all the sections from census_poly contained in a district. Visually, the external border of districts matches perfectly with the borders of the census sections.       Still when I run this query  SELECT "census_poly".geom    FROM "census_poly"    JOIN "district_poly"    ON ST_Contains("district_poly".geom, "census_poly".geom)   I get this    which excludes all the bordering census districts (FALSE NEGATIVE) such as these    I wonder why they are excluded and how to tweak my query to include them.   I could use the centroids of the census sections but that would not indicate whether a section is truly over two districts (TRUE NEGATIVE). Should I define a small buffer around my districts?

Ok, I have to admit, I don't really delve too deep into the semantics of the spatial operators list below, I'm more of a user, I write software to drive the SQL most of the time and don't really think about it too much.  However, I have a situation where a spatial operation I'm doing is going dog slow, on a table that has great indexes on and has never caused a problem before now.  As a result, I'm trying to figure out which of the following is my best bet to use, that will give me the best performance, however, sometimes I find my searches don't return anything when I know they should, and sometimes return stuff when they shouldn't.  SO I'm reaching out, to ask if some one can give me the actual definition, such as criteria to match, fully within enclosing geometry, or within outer ring etc etc of each of the following operations:  Equals(Geom1, Geom2):int Disjoint(Geom1, Geom2):int Touches(Geom1, Geom2):int Within(Geom1, Geom2):int Overlaps(Geom1, Geom2):int Crosses(Geom1, Geom2):int Intersects(Geom1, Geom2):int Contains(Geom1, Geom2):int Relate(Geom1, Geom2):int   If you can give a concrete example of when they will and will not match too, that would be great.  For reference, I'm searching on a table of Linestrings, using a rectangular polygon, rotated to be pointing in the direction of travel (It's part of a traffic managment app)  For further reference, here is a sample of the SQL the app generates to perform a search:  SELECT recordID,AsBinary(geometry) AS geometry,Distance(GeomFromText('POINT(-1.84101 54.85078)',4326), geometry) AS distanceFromGps FROM linegrid WHERE Intersects(GeomFromText('POLYGON ((-1.8413149820810311 54.850782468607292, -1.8409507853094111 54.850952257034713, -1.8408279009723911 54.850864894077496, -1.8411920982612455 54.850695105650068, -1.8413149820810311 54.850782468607292))'), geometry)   You can see in this example I'm using intersects trying the others as mentioned doesn't quite give the results I expect, hence why I'm asking the question.  Please note, I'm not particularly bothered about actual faster/other ways of doing this at the moment, BUT if you do happen to spot a better way do feel free to shout up :-)  For now all I'm mostly trying to understand is the differences between each of the operations.  As for doing it faster/better I intend to open a different question for that at a later date.  For more reference, the Spatial engine this is working against is Spatilite 2.3.0, and I can't upgrade it due to the devices it's running on not having a more up to date build for it (Windows CE)    I'm going to choose mintix'es answer here as that provided a super easy to understand grid and description of all the various operations, which answered my question.  I'm still faced with getting performance on the routines up, but I do now have a few strategies to try on that one, I may still seek advice here from the group with regards to that.  @Vince deserves some credit too, as that white paper is definitely the definitive answer, but it's also quite challenging to read (I had to read through it several times) , for anyone wanting the real I am on these operations The Clementini paper is the way to go, if you need an easy to understand overview while developing solutions however, the FME link should be open in another browser tab.


I currently work for a very large company as a GIS developer, and while I am happy in my position for the most part, I can't help but wonder what life as a GIS consultant (i.e. working for myself) would be like...  I know there are many excellent GIS consultants on this site, and I am wondering on how they got their start.  Are there any good sites where companies and/or organizations post GIS related requests?  Can they offer any strategies on how they market themselves to companies/organizations?  Any other tips to test the waters per say?  I'd also be interested in hearing about life as a GIS consultant.  Any experiences or thoughts welcome.

The post  listed resources for finding a GIS job (as in a full-time or contract position).  What resources are available for finding GIS projects or consultancy work? eg:   a small project to integrate a map into an existing site; incorporate an address-search into a workflow; migrate legacy GIS code to a new format;   These are one-off tasks which require a GIS professional, but which don't entail a full-time position. How do you find the right people for the task, or find the task if you're the right person? All the online resources I've seen are aimed at "jobs".


I have a bunch of machines that need to fetch https: off a server (or collection of servers). I'm operating a CA and self-signing the certificates on the server(s).  The client machines are running ubuntu. Some of the fetches are via apt, some via wget.  How do I install the CA's certificate on the clients so that all of its certs are recognized without warnings or errors? (Just the directory location is sufficient, I'll package it in an appropriate way.)  Thanks.

My work has decided to issue their own  (CA) to handle different aspects of our work securely without paying for certificates.   Cryptographically sign emails Encrypt email contents Make access to things like the company  client-certificate based. Revoke the keys of former employees automatically   They sent me a .pem file, and I'm not sure how to add it to my Ubuntu install. The instructions sent were: "Double-clicking on it on a Mac should install it."   How do I proceed? Do I need to do something with  to create a .key, .csr, or .crt file?


I extracted this from L.R.H Chapman grammar two book. An example was given like this :  Question : Who did jack meet at the station? Answer : Jack met his uncle at the station  I am not sure whether is it correct to make every question like the example format given above. Is this sentence correct? Question : who did the rich woman pay yesterday? Answer : The rich woman paid her servants yesterday. I assume that the correct sentence would be "To whom did the rich woman pay yesterday?" Here are the sentences for questions to be made :   The rich woman paid her servants yesterday. I saw a lot of soldiers outside the palace. The angry man hit the boy. Mary wrote a letter to her aunt. The teacher helped the weak pupil. The old man knew everybody in the village.

I can never figure out whether I should use who and whom. Most people use who for both colloquially, but some people say this is not correct.  What’s the rule for using who and whom correctly?


With git rebase --interactive <commit> you can squash any number of commits together into a single one.  That's all great unless you want to squash commits into the initial commit. That seems impossible to do.  Are there any ways to achieve it?    Moderately related:  In a related question, I managed to come up with a different approach to the need of squashing against the first commit, which is, well, to make it the second one.  If you're interested:

Suppose you have a history containing the three commits A, B and C:  A-B-C   I would like to combine the two commits A and B to one commit AB:  AB-C   I tried  git rebase -i A   which opens up my editor with the following contents:  pick e97a17b B pick asd314f C   I change this to  squash e97a17b B pick asd314f C   Then Git 1.6.0.4 says:  Cannot 'squash' without a previous commit   Is there a way or is this just impossible?


I am looking to set up a connection from our website, to populate leads, and am struggling to find the right authentication method. Previously (using a different CRM), we simply POSTed a json payload to a specific endpoint (/api/leads) with an auth token header. The token was generated via the CRM admin panel, and valid until revoked, so was simply 'hard coded' into the app (actually using environment variables). curl      -H "Authorization: Token token=sfg999666t673t7t82"      -H "Content-Type: application/json"      -d '{"lead":{"first_name":"Eric", "last_name":"Sampleton", "mobile_number":"1-926-652-9503"}'      -X POST "https://domain.freshsales.io/api/leads"  I cant seem to find anything similar for Salesforce though. Since this is automated, OAuth doesnt seem suitable. Web-to-lead appears to be outdated, and doesnt provide a response, so we cant access the salesforce lead id, and I have no intention of even looking at SOAP docs! Is a similar flow available for salesforce (permentant token / API key), and if not, what is the simplest alternative

I really need to get permanent token or dynamic generator. We set job in the server and this service will come to salesforce and get the data. To provide this, I created connected app, got the token from postman by myself and gave it. After a while (approximately 1 day), we faced with session id problem.   What can I do?


Recently, I installed Ubuntu 17.04 on a new ssd (standard installation with ext4), no other drive was connected at that time. After I connected my data hdd (ntfs formatted, it's a dual-boot setup with win7), I noticed that every single file on it got the execute flag (had a dual-boot with 14.04 before, but did not have this problem).  If I toggle the flag off on a single file, it is immediately reset. Also, every file that I copy to the hdd gets the flag and if I create a link to a hdd folder on my ssd, the link itself gets the flag after a renoot, making it unusable until I remove the flag (it is reset on the next reboot).  The entry for the ntfs drive in /proc/mounts :  dev/sdc1 /media/brad/mydata fuseblk rw,nosuid,nodev,relatime,user_id=0,group_id=0,default_permissions,allow_other,blksize=4096 0 0    Why did this happen (I did not do anything that should have caused this/how to prevent it from happening next time)? How do I safely undo it for the whole drive at once without touching/changing each file (also without changing file date stamps)?   Re:duplicate:  I don't see what this would have to do with chmod, I don't want to change file or folder permissions, I need to correct how ubuntu is seeing the whole drive because that has been changed and I think that change was a very bad decision. So now I have to edit fstab to get the pre-16.10 behavior back. There is no mention of this situation or of the 'correct' (old) permissions one has to set in "How do I use 'chmod' on an NTFS (or FAT32) partition?". While renaming this question to "Reverting ntfs permissions to pre-16.10" might make it more unique, somebody with the same problem does most likely not know about the reason and therefore would not find this thread, so I keep it like it is.  Still waiting for the wrong "Duplicate" note to be removed. This is how a duplicate looks:

I have a script that I need to execute on an NTFS partition. The script's permission is set to 600.  I attempted to modify the permissions by running chmod 755 script.sh, which doesn't report a failure or anything - but it also doesn't change the permissions on the file:  $ stat script.sh    File: `script.sh'   Size: 297070      Blocks: 584        IO Block: 4096   regular file Device: 811h/2065d  Inode: 35515       Links: 1 Access: (0600/-rw-------)  Uid: ( 1000/  xxxxxx)   Gid: ( 1000/  xxxxxx) Access: 2010-09-30 14:05:16.041621000 -0700 Modify: 2010-09-30 14:05:05.070157000 -0700 Change: 2010-09-30 14:05:05.070475000 -0700  $ chmod 755 script.sh $ stat script.sh    File: `script.sh'   Size: 297070      Blocks: 584        IO Block: 4096   regular file Device: 811h/2065d  Inode: 35515       Links: 1 Access: (0600/-rw-------)  Uid: ( 1000/  xxxxxx)   Gid: ( 1000/  xxxxxx) Access: 2010-09-30 14:05:16.041621000 -0700 Modify: 2010-09-30 14:05:05.070157000 -0700 Change: 2010-09-30 14:05:05.070475000 -0700   As you can see, it remains unchanged.


A problem from Griffith's Introduction to Quantum Mechanics asks to prove the following:  Given a symmetric potential $V(x)$  $(=V(-x))$, the solutions to the time-independent Schrödinger's equation can always be take to be either odd or even.  I understand that given a solution $\psi(x)$, $\psi(-x)$ is also a solution.  Now, $\psi_{even}(x) = \psi(x) + \psi(-x)$ and $\psi_{odd}(x) = \psi(x) - \psi(-x)$ are also solutions to the equation.  Thus $$\psi(x) = \frac {1}{2}(\psi_{even}(x) + \psi_{odd}(x))$$  But $$\psi_{even}(-x) + \psi_{odd}(-x) = \psi_{even}(x) - \psi_{odd}(x)$$  and hence $\psi(x)$ is neither even or odd!  I am unable to resolve this issue.

I have done the Problem 2.1 in Griffiths' quantum mechanics,  and it seems not making sense to me.  What if the wave function isn't symmetric at all?  Then obviously the proof doesn't work. The solution confuses me.      If $V(x)=V(-x)$ then the "position" wave function can always be taken to be either even or odd.


I want to create a new account on Stack Overflow, starting from scratch, focusing it on other kinds of questions. I dont want to merge my two accounts; I want to have the two accounts.  It is legal and safe to have them in Stack Overflow? Can I be sure that the accounts wont be merged?

Take this example: .  I can imagine of any human reasons to create a new user account at SO, e.g. willing to restart with a clean (reputation) history. But particular this one is extreme. The user known as "icepax" currently already has 10 accounts, each involved in only one question/answer.  How and why would one do that? There is certainly more at matter here. Shouldn't it be our task to merge the accounts and inform the user in question about how to use SO and the OpenID properly?


What should we use in the following sentence, were or was:     Our only guide _____ stars.    What is the grammar rule for the usage of Singular and Plural forms of verbs?

They tried anti-acids, also anxiety drugs in case the problem was my   nerves. In the end, they sent me home since my life wasn’t in danger.   Should it be was or were and why?  I tried using  but I couldn't get an answer.


Are there real-valued functions $f$ and $g$ which are neither each other's inverses, the identity, nor linear, yet exhibit the behaviour $$f\circ g = g \circ f?$$  Examples such as $f(x) = 2x$ and $g(x)=3x$ are "trivial" in this sense.   Moreover, given a function $f$, can one go about obtaining an example of a function $g$ which commutes with $f$?   I suppose this would be similar to fixed point iteration? E.g. if $f\colon\mathbb R\smallsetminus\{1\}\to\mathbb R$ is defined by $f(x) = 2x/(1-x)$, I would need a function $g$ such that  $$g(x) = f^{-1}\circ g\circ f =\frac{g(\frac{2x}{1-x})}{2+g(\frac{2x}{1-x})},$$ so maybe choosing an appropriate "starting function" $g_0$ and finding a fixed point of $g_{n+1} \mapsto f^{-1}\circ g_n\circ f$ would be a possible strategy, but I can't seem to find a suitable $g_0$.

Today I was thinking about composition of functions.  It has nice properties, its always associative, there is an identity, and if we restrict to bijective functions then we have an inverse.  But then I thought about commutativity.  My first intuition was that bijective self maps of a space should commute but then I saw some counter-examples. The symmetric group is only abelian if $n \le 2$ so clearly there need to be more restrictions on functions than bijectivity for them to commute.  The only examples I could think of were boring things like multiplying by a constant or maximal tori of groups like $O(n)$ (maybe less boring).  My question: In a euclidean space, what are (edit) some nice characterizations of sets of functions that commute? What about in a more general space?   Bonus: Is this notion of commutativity important anywhere in analysis?


I've never had an Xbox 360 but I want to get one. I don't want to do any hardcore gaming like Halo, only lighter stuff like the Skate games and Family Guy, Back to the Multiverse. So, in order to decide if the 4GB edition is good enough for me, I'd like to know what does the XBox need the hard drive for? Do games require to be installed on disk perhaps? What about demos or XBLA?

I want to get a 360 and don't know wether to get the bigger (250GB), newer, more expensive Elite, or get one of the older, smaller (120GB), last gen ones. I know the arcade is going to be too small to save anything useful  How much hard disk space is recommend? What else is stored besides games?


With man bc, I have a line starting with bc(1).  bc(1)                                                                    bc(1)  NAME        bc - An arbitrary precision calculator language   Some of the Unix book also describes Unix commands with (1) attached just like this SO question - . What does this mean?

So, for example, when I type man ls I see LS(1). But if I type man apachectl I see APACHECTL(8) and if I type man cd I end up with cd(n).  I'm wondering what the significance of the numbers in the parentheses are, if they have any.


The app doesn't have a way to show your own questions. It would be nice to get a quick handle to those.

I want to see all my Questions and Answers in a particular SE site -  - profile page through Stack Exchange Android App. How can I see that? When I tried to see that I found only Top Posts(5) and Top Tags.


I would like to solve:  $$\dot{y} = -\frac{2y(t)}{5t} +\frac{3}{5y(t)^4} $$  I was given a hint to use the transformation.  $$ z(t) = t^\alpha y(t)$$ where $\alpha \in \mathbb{R}$. I've seen this been done before but it seems like you just guess the solution. Is there a way to go about this?

Consider equations defined in $D_x = (0,\infty) \times (0,\infty)$  1) Find the maximal solution to  $$ \dot y = \frac{3t^2}{5y^4} $$ satisfying the initial value problem $y(1) = 2^{\frac{1}{5}}$  I have found the maximum solution to be $((0,\infty), (t^3+1)^\frac{1}{5})$  2) Find the maximal solution to   $$ \dot y = -\frac{2y}{5t}+\frac{3}{5y^4}$$  satisfying the IVP $y(1) = 2^{\frac{1}{5}}$.  (HINT: Use a transformation of the form $t^{\alpha}y(t)$.   I hope someone can explain how to use the transformation to find the maximal solution.


If I have two "entangled" particles and I know the spin state of every one of them. Then, I change the spin state of one of the particles, will it affect the spin state of the other particle even if it is far away? Also, it turns out that entanglement is actually real and can be used for many things, is this just the result of a false interpretation and understanding of Quantum Mechanics by those who claim it or it can be really done? And if it is real, will it just change our interpretation of GR?

Bearing in mind I am a layman - with no background in physics - please could someone explain what the "big deal" is with quantum entanglement?  I used to think I understood it - that 2 particles, say a light-year apart spatially, could affect each other physically, instantly.  Here I would understand the "big deal".  On further reading I've come to understand (maybe incorrectly) that the spatially separated particles may not affect each other, but in knowing one's properties you can infer the other's.  If that it the case, I don't see what the big deal is... 2 things have some properties set in correlation to each other at the point of entanglement, they are separated, measured, and found to have these properties...?  What am I missing? Is it that the particles properties are in an "un-set" state, and only when measured do they get set?  (i.e. the wave-function collapses).  If this is true - why do we think this instead of the more intuitive thought that the properties were set at an earlier time?


These people are at an arctic base, at least I think it was set in the arctic. I know it was extremely rural/barren. But this alien pod landed and the crew were terrified of it except for one person, we'll call him B, who believed the alien was gentle and wasn't aware that it could / was causing harm.   I remember they killed the alien and B was horrified and said something about how the alien didn't mean any harm. Another crew member says something along the lines of "I pray you're correct. Because another pod just landed in [insert location]" and it ends on that cliffhanger where you don't know if it's the beginning of an alien invasion or if the creature really was wrongly murdered.   I remember seeing it on TV sometime around 2000-2004. It definitely wasn't The Thing, just some obscure film I just happened to see.

I've been trying to find the name of a movie I remember seeing on TV on several occasions. What I remember of the plot:   A probe/satellite returns to earth It's brought to an underground facility and is studied An alien bacteria onboard spreads, taking over the computer, infecting people and growing into a monster (John Carpenter/The Thing style) The facility is nuked at the end of the movie to kill it off, but you see the alien escaped the facility, walking off-screen as the bomb goes off.   I've been scouring lists of sci-fi movies to no avail. Sound familiar to anyone?


I've just got  on Stack Overflow.        But it is not displaying in my badges. Badge count is also not increasing. :'(

I've just earned the Electorate badge on , but  doesn't display it. For proof that I've actually earned the badge, here's a screenshot:    Why is the badge not showing up in my profile?


My wizard wants to do a spell combo, it will take two turns. Enlarge/Reduce then Catapult  Cast enlarge on a vial of acid.  It weighs 1 pound and per the spell description it will grow to 8 pounds.  So it will have 8 times the volume and therefore it will do 8 times the damage. 16d6 instead of 2d6.  How to deliver it?  Cast catapult on the large vial at level 2, because it weighs 8 pounds now, doing 4d8 damage + 16d6 acid.  A whopping 128HP max.  Average 74.5 (if it hits) The 5E Player's Handbook page 237. says  The target's size doubles in all dimensions, and its weight is multiplied by eight  The acid vial will weigh 8 times as much so I am simply assuming that there is 8 times the amount of acid Does this work?  If not, why?

One of my players is constantly bugging me about using Enlarge/Reduce to reduce a boulder to a smaller size and then hurl it via the spell Catapult, cancel the concentration on Enlarge/Reduce before the impact, and let the enemy be smashed by a much bigger one.  Can the Enlarge/Reduce and Catapult spells be combined in this way?


Suppose $F(x)$ is a polynomial having coefficients in the field of reals ( $\mathbb{R}[X]$ ) .  $F(x)$ has the property that $y \geq 0 \implies F(y)$ is nonzero.( $y$ is a real number ) Can we find a polynomial $T(x) \in \mathbb{R}[X]$  so that $T(x) \cdot F(x)$ has all its coefficients non-negative ?

The following is an exercise (Exercise #3 (a), Chapter 3, page 28) from Richard Stanley's Algebraic Combinatorics.  Let $P(x)$ be a nonzero polynomial with real coefficients.  Show that the following two conditions are equivalent:  There exists a nonzero polynomial $Q(x)$ with real coefficients such that all coefficients of $P(x) Q(x)$ are nonnegative.  There does not exist a real number $a > 0$ such that $P(a) = 0$.    That the first item implies the second is straightforward (since if $a$ is a positive real root of $P(x)$ then it is a positive real root of $P(x)Q(x)$, but since $P(x)Q(x)$ is nonzero with all coefficients nonnegative, this is impossible).  However, I can't seem to find a way to prove that the second item implies the first.  I would very much like to see a proof if someone can provide it.


I recently broke my kit lens for my 450D and have been looking into replacements. At the moment i have a 55-250 mm objective as my primary objective since it is all i have at the moment.   My question is mostly based on the fact that i have found the 18-55 IS II lens for ~135$. Meanwhile i've spotted the 1300D with the same kit lens (18-55 IS II) for about ~350$~280£. Is the jump in price worth it for the kit lens only or the whole package?

As the question says, when should I upgrade my camera body? In particular, if I have a low- to mid-range body (A DSLR such as a Nikon D3200 or Nikon D5100, or Canon SL1 or T5, or a mirrorless camera such as a Panasonic GH3 or an Olympus E-PL6). How do I know when I need to upgrade?  I have a complement of "kit" lenses, such as an 18-55mm f3.5-5.6 and a 55-200mm f4-5.6. Maybe I've even added a 50mm 1.8 to the kit. Flash is only for indoors (right?) and I usually shoot outside, so that means I don't need an external flash.  I shoot photos of my family and friends whether out at the park or having a picnic, my kids sports practices and games, vacation photos, as well as some landscapes, flowers, and whatever else catches my eye. Pretty familiar territory. I'm not a professional and don't intend to become one.


Would you explain the lyric "Blessed be the mystery of love" in the song "Mystery of love" by Sufjan Stevens please? Why the song writer use the word "be" instead of "is"? Full lyrics of the song:

What is the grammatical interpretation of the phrase?  I don't understand what verb tense or voice is used.


I am developing an application. I initially wanted to allow the user to ONLY select a Monday. After spending a considerable amount of time, I found out that that wont be possible unless i create my own control.  Therefore i wanted to know how do I make Monday's Bold (and even change the background color) so it's more noticeable?  Is there a way to programatically select a Monday (of the same week) no matter what day is selected on the week?  For example, if they click 2/16, that 2/13 would automatically be selected.

How do I find the start of the week (both Sunday and Monday) knowing just the current time in C#?  Something like:  DateTime.Now.StartWeek(Monday);


done=False  while not done:     for level in range(1,13):        Code...         while running:             Code.....              #10 - Win/Lose check              if healthvalue<=0:                 done=True                 running=0                 exitcode=0                 print "aaa"   I have got this game on python which when the health is lower than 0, it should quit the loop. However, even though I state it so that done=True in the if statement, the loop still does not quit although running does become 0. I also checked by printing "aaa", and it does print, but yet done does not equal True in order to quit the loop.  Please help! Does it have something to do with the for loop?

Given the following code (that doesn't work):  while True:     #snip: print out current state     while True:         ok = get_input("Is this ok? (y/n)")         if ok.lower() == "y": break 2 #this doesn't work :(         if ok.lower() == "n": break     #do more processing with menus and stuff   Is there a way to make this work? Or do I have do one check to break out of the input loop, then another, more limited, check in the outside loop to break out all together if the user is satisfied?


This question is similar to one asked if virtual electrons exist outside the nucleus, but please note, my question says virtual particles. It is not a duplicate.  I read so often that matter is mostly empty space and the electron is some fantastically large distance from the nucleus that matter is mostly empty space. We know there is actually an electron cloud that fills the nucleus that reflects the probability of finding the electron. Are there virtual particles and anti particles popping in and out of existence in any of the spaces surrounding the nucleus? The same ones that produce the energy of the vacuum. I ask because there many textbooks that insist we are all mostly made of empty space since there is so much of it surrounding a nucleus.

I have heard  pop in and out of existence all the time, most notable being the pairs that pop out beside black holes and while one gets pulled away. But wouldn't this actually violate the conservation of energy?


I'm trying to understand abstract classes in Java so I wrote this code snippet in IntelliJ:  AutoCloseable ac = new BufferedInputStream(new InputStream() {         @Override         public int read() throws IOException {             return 0;         } });   The @Override and read() stub was created automatically by IntelliJ.   Since InputStream is an abstract class, why can I instantiate it with the new keyword?    And another thing. When I delete the method stub like this:  AutoCloseable ac = new BufferedInputStream(new InputStream());   The IDE says that InputStream is abstract and therefore can't be instantiated (as expected).  So, why is the former valid and the latter not?  And where does this read() method come from?

What is the use of anonymous classes in Java? Can we say that usage of anonymous class is one of the advantages of Java?


In X-Men 3: The Last Stand, which was explicitly in continuity in the timeline from which Wolverine was sent back to the past, Jean destroys Xavier's body.  The answers to  and  explain that, as shown in  for The Last Stand, Xavier escapes to a comatose body which is actually his identical twin (hence still played by Patrick Stewart).  But surely this twin would never have received the gunshot wound to the spine which causes his paralysis, so why is he still in a wheelchair?

In X-Men 3:The Last Stand, we see that Professor Charles Xavier died and Jean Grey killed him, and his body turned into pieces.  But in X-Men: Days of Future Past he's alive and well.  I'm pretty surprised that nobody asked about this before. Maybe the answer is too obvious and I'm missing something in the previous movie. I'm not following the comic, so I don't know that maybe this movie is set in an alternate universe.  ADDITION: in the extra scene after the credits in X-Men 3: The Last Stand we see that Xavier has transferred his consciousness to the other body. But his own body already destroyed, so how can he regain his original body?


JsFiddle has a nice demo but only works up to jquery 1.8. Here is the link:   Add Another Input Box                        $(function() {     var scntDiv = $('#p_scents');     var i = $('#p_scents p').size() + 1;      $('#addScnt').on('click', function() {         $('
<input type="text" id="p_scnt" size="20" name="p_scnt_' + i +'" value="" placeholder="Input Value" /> Remove
').appendTo(scntDiv);         i++;         return false;     });      $('#remScnt').on('click', function() {          if( i > 2 ) {             $(this).parents('p').remove();             i--;         }         return false;     }); });   Version 1.9, it needs Migrate 1.1.0 to be able to have "Remove" work as expected.  Version 1.10 and later won't work for both .live and .on

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


Photons are packets of electromagnetic radiation (wave), what about other particles? Are other particles, say electrons, really just packets of waves?

I often hear about the wave-particle duality, and how particles exhibit properties of both particles and waves. However, I wonder, is this actually a duality? At the most fundamental level, we 'know' that everything is made up out of particles, whether those are photons, electrons, or maybe even strings. That light for example, also shows wave-like properties, why does that even matter? Don't we know that everything is made up of particles? In other words, wasn't Young wrong and Newton right, instead of them both being right?


I have seen this computer where when the computer boots up, the grub screen lets him choose operating systems. as the four ubuntu choices like ubuntu recovery and stuff are still there, there is a fifth choice that says windows seven loader. is that possible to do on my computer( Ubuntu 12.04 ). if so, please suggest how.  Thanks :)

I need my pre-installed version of Windows 7 (or any other version of Windows), how could I install Ubuntu without erasing it?


I am using  so that user's can sign up to a MailChimp mailing list. I want the signups to go into a specific group in my list. The plugin doesn't appear to work correctly with mailing list groups.  Can I just dive into the plugin code and add a hidden field to force the users into a certain list?  I tried digging around in there and it looks like the group is determined from an input called "interests". I have tried sending the form with a hidden field with this name having the value of the name of the group I want to use, like this:  <input type="hidden" name="interests" value="Group Name" />   But this does not work. Digging around on Google doesn't seem to offer much help either, as there only appears to be other confused users or not much interest in this particular aspect of the plugin.  How can I do this?

I want a description under the user name input field in the Wordpress registration form like in the next example. How can I do this?  //create an extra field in login page for invitation code add_action( 'register_form', 'add_invitation_code_field' );  function add_invitation_code_field() {    ?>
                       Invitation code             <input id="invitation_code" class="input" type="text" size="20" value="" name="invitation_code"/>             <?php _e("Description text"); ?>
    <?php }


How do I use efuse? I have never dual booted Ubuntu This is a new laptop with only one program installed.

I have Ubuntu on my laptop. Now I want install Windows 7 in a dual-boot. How can I do this? I can't lose my Ubuntu files, and I'm afraid that I might break . Go  for UEFI only!


Let $V$ be a vector space. In order to show that any linearly independent set in $V$ can be extended to form a basis, or equivalently, any basis of a subspace of $V$ can be extended to a basis of $V$, is it required to use choice principles (i.e. Axiom of Choice or weaker forms of Choice). If so, what is the weakest choice principle that can prove this statement?

In discussing , I noted that while the statement:     Any vector space has a basis   is equivalent to the axiom of choice, I wondered if the statement that:     Any vector space either has a finite basis or an infinite set of linear independent vectors   was weaker than the axiom of choice. It feels weaker - it feels like you can inductively define a countably infinite set of linearly independent vectors without full choice, but I'm not sure if that is possible with ZF alone, or requires all of the Axiom of Choice, or is weaker but requires some form of choice.


I was looking at my admin panel for the router and saw a computer I don't recognise. I changed the password, reconnected my devices, and it's gone.  Well, it came back again today. It's very annoying, as google bases a lot of things (search suggestions, etc) based on your IP and I keep getting stupid suggestions.  I'm assuming it's one of my neighbors, I'm just not sure which.  I would just change the password, however whoever is doing it clearly has a way to get on secured wifi networks and that wouldn't be any help.   Neither of  answers helped me. They're probably spoofing their MAC or something.  My router is a

I'm soon going to be setting up a wireless network for me and some buddies and (hopefully) making it secure. I have some questions and concerns regarding this and figured someone here could give me a hand and steer me in the right direction.   I have a WRT55AG (version 2) loaded with the factory firmware. I've heard that it's possible to load your own firmware onto routers like these. Is it worth it? What can be achieved with it? I was wondering what kind of security I should use on my wireless. Ideally I would want all devices to be 'accepted', but I'm not sure how to accomplish this. I'm guessing it has something to do with MAC addresses, but I don't know the first thing about them. It would be great that ALONG WITH encryption (I'm told WPA2 is the best), every device would need to be added to a list of some sort before even being able to access the AP. Another feature I was thinking of would be completely hiding my wireless from showing up on other people's computer. Is this possible (like an SSID broadcast thing). Is it worth the trouble? One more option I was looking to implement would be bandwidth calculators. Ideally something in the router to measure the amount of bandwidth being used and how much has been used for that month (this has to do with bills and limits, obviously). Is it possible to throttle down speed when a certain limit is reached?   These are alot of points but I was hoping someone who has more knowledge than me in this subject could give me a hand and a few pointers. Hopefully all this is possible and I'm not dreaming :)


I am trying to use the Kleene's O ($\mathcal{O}$) in some equations to represent a zero matrix. However, I am using Times as my standard math font and do not like the look of the symbol and would like to set it back to the standard font.  How can I set the math font to standard for just a single symbol. I would like to create a command permitting me to do so as such:  \newcommand{\zeromatrix}{\mathcal{O}}   How can I however set the font for the single symbol inside back to standard?  Thanks in advance for your help!  Edit: Here's a minimal working example of my document with the math font set to Times:  \documentclass{article} \usepackage[utf8]{inputenc} \usepackage{mathptmx} \begin{document}     $\mathcal{O}$ \end{document}

Is there a general way to change the font of a particular symbol without switching packages?  For example, suppose I'm using Computer Modern for my entire document, but I want the "subset" operator to look as it does in mathabx.  How can I redefine it to appear in this way?


First off, I would like to apologize if I am posting this in the incorrect location, as I am not sure where else to put this.  I use Stack Overflow all the time, and I have always wondered if a "select all" option could be added to large amounts of code.

I might just be lazy, but do you ever find it tiresome to select all the source code from a large post on Stack Overflow to copy it?  I would like a feature, possibly a Firefox extension, but preferably a JavaScript script, for automatically copying source examples to the clipboard. It's no big deal for a small snippet, but a 1000+ line posting is cumbersome to copy.  Do you guys have a better way of copying large source posts? I'm using Firefox 3.5.5 on Windows 7.


Is there a name for words like whatchamacallit, doohickey, thingamabob, doodad, thingamajig, whatsit, etc.?  Somehow it seems like there should be a word to describe the general term for .  (Computing names like foo, bar, baz are examples of  but those are a slightly different category.)

{This question came to mind because of the recent question ..  }  In my opinion, in English, it's reasonably common that—strangely enough—there is no word for a certain reasonably common thing. And indeed, speakers prefer to use an ad-hoc description for the thing in question on an ongoing basis, rather than, as you'd probably expect, a specific or technical word falling into general use and coming to be "the word" for the thing. {Contrast milieu such as say Germany or Japan, where the culture, within 12 seconds, codifies exact, specific, universally-accepted terms for anything that comes along, whether a cultural phenomenon, technical object, or the like.}  I think of this as "the Thingy substitution", or the things in question as 'thingy things' because, well, they are usually referred to as     the thingy that...   The perfect example is      the thingies on jigsaw puzzle pieces.   (Note that, 100% of English-native speakers will understand exactly what I am referring to.)  To repeat, native English speakers—in my opinion—prefer to stick (even over decades) with ad-hoc thingy-esque multi-word descriptions rather than adopting a new word generally accepted.  {On the other hand, of course, the etats-unis in particular is notorious for generating zillions of acronyms and other coinages—however, I don't think the two concepts are at odds, both are true.}  Now there's possibly a term for this phenomenon among linguists e.g., "grasp words", "thingy words" or "ad-hoc non-naming conventions" etc.   (a) Does anyone know such a term? (b) Indeed, does anyone agree that this is a phenomenon amongst particularly English speakers? (c) Indeed, is this all well-known and explored by academic linguists/etc and I'm just behind the times?


How's Monte Carlo different from random sampling with replacement?  Because Wikipedia page for Monte Carlo says:     Monte Carlo methods vary, but tend to follow a particular pattern:         Define a domain of possible inputs    Generate inputs randomly from a   probability distribution over the domain    Perform a deterministic   computation on the inputs    Aggregate the results      Isn't 2 about doing exactly the same thing as sampling with replacement?  Or is it Monte Carlo, because one does 3. and 4. in addition?

I am trying to understand difference between different  (Monte Carlo simulation, parametric bootstrapping, non-parametric bootstrapping, jackknifing, cross-validation, randomization tests, and permutation tests) and their implementation in my own context using R.  Say I have the following situation – I want to perform ANOVA with a Y variable (Yvar) and X variable (Xvar). Xvar is categorical. I am interested in the following things:  (1) Significance of p-values – false discovery rate  (2) effect size of Xvar levels    Yvar <- c(8,9,10,13,12, 14,18,12,8,9,   1,3,2,3,4) Xvar <- c(rep("A", 5),  rep("B", 5),    rep("C", 5)) mydf <- data.frame (Yvar, Xvar)   Could you gel me to explain the  sampling differences with explicit worked examples how these resampling method work?  Edits: Here are my attempts:  Bootstrap  10 bootstrap samples, sample number of samples with replacement, means that samples can be repeated     boot.samples <- list() for(i in 1:10) {    t.xvar <- Xvar[ sample(length(Xvar), length(Xvar), replace=TRUE) ]    t.yvar <- Yvar[ sample(length(Yvar), length(Yvar), replace=TRUE) ]    b.df <- data.frame (t.xvar, t.yvar)     boot.samples[[i]] <- b.df  } str(boot.samples)  boot.samples[1]   Permutation: 10 permutation samples, sample number of samples without replacement   permt.samples <- list()     for(i in 1:10) {        t.xvar <- Xvar[ sample(length(Xvar), length(Xvar), replace=FALSE) ]        t.yvar <- Yvar[ sample(length(Yvar), length(Yvar), replace=FALSE) ]        b.df <- data.frame (t.xvar, t.yvar)         permt.samples[[i]] <- b.df      }     str(permt.samples)     permt.samples[1]   Monte Caro Simulation     I am not sure about all above terms and whether my above edits are correct. I did find some information on  but I could not tame it to my situation.


Didn't find anything by googling. So far I worked through proving this by assuming the limit is 8 until there is a contradiction. Eventually I got: $\epsilon > \left | 7x-3-11 \right |$ and $\epsilon > \left | 7x-11 \right |$ which seems like a contradiction. Is this correct? If so how do I proceed?

I want to use $\epsilon-\delta$ formulation to prove that $\lim_{x\to 1 } 2x+3 \neq 6$.  I know that I need to show that there exists an $\epsilon>0$ such that for every $\delta>0$ there exists $x\in \mathbb{R}$ such that $0<\left| x-1 \right| <\delta$ but $|2x-3|\geq \varepsilon$.  Will someone please guide me through the process?  Thanks a lot in advance


I did a factory data reset on phone and it still wants the last synced Google account.   I found phone and would like to bypass factory reset protection, how do I do it?

I won a Samsung Galaxy S6 Edge, signed into it with my Google account, played around with it, wiped it, and sold it.  Now the person can't get past setup because it's saying he must login with an account previously synced to the phone.   Is there anything I can do from my side to remove this lock?


when I run  sudo cd /root it says sudo: cd: command not found but it works perfectly fine if I first sudo su and then do cd /root. Isn't sudo supposed to give me root privileges?

I want to run a command on a shell on behalf of another user. The command is as follows:  sudo -u USER cd /home/USER   I get  sudo: cd: command not found   What is the correct syntax for the command to pass to sudo?


My first intuition was to think $P(\{\text{No two bdays coincide}\}) = \displaystyle{\frac{\binom{365}{n}}{365}}$ given $365 \ge n$. Turns out $P(\{\text{No two bdays coincide}\}) = \displaystyle{\frac{365 \cdot 364 \cdots (365 - n + 1)}{365^n}}$. Why is it important we line up the people instead of simply dealing with subsets? What do we undercount when we solve this problem according to my initial intuition? Thanks. Edit: Came here to understand the combinatorial reasoning behind the question, but I got a much better (obviously, personal opinion) answer based on probabilistic reasoning. That answer might be beneficial to future students struggling to grok the classical solution to this problem. Here it is below: Let $A_i$ be an event where the $i$th person shares bday with none of the $n−1$ people. Then we have $P(\bigcap_{i-1}^n A_i) = P(A_1)P(A_2\mid A_1)P(A_3\mid A_1, A_2)\cdots P(A_n\mid A_1,\ldots A_{n-1}) = \frac{365}{365} \cdot \frac{364}{365} \cdots \frac{365 - n + 1}{365}$

Given there are 365 days in a year and $n$ people, the probability that at least two people have the same birthday is given by  $$\frac{365^n - 365 \cdot 364 \cdots (365-n+1)}{365^n}.$$ In this calculation, we treat the $n$ birthdays we selected as a sequence where their order matters.   If we think the $n$ dates that randomly selected as a set where the order does not matter, I believe we would have the probability $$\frac{{365+n-1 \choose n} - {365\choose n}}{{365+n-1 \choose n}}.$$   For the total number of outcomes, we model by throwing $n$ balls uniformly randomly into $365$ boxes. Essentially, there are $n$ balls and $365-1$ walls (between the boxes). For example $$ \circ |\;\;\; |\;\;\;|\circ \circ |\;\;\;|\circ |\cdots |$$ would mean one person was born on day $1$, two people were born on day $4$, one person was born on day $6$, and so on. This is how I came up with the ${365+n-1\choose n}$. For the case that everyone has a distinct birthday, it would be ${365 \choose n}$.   What is wrong with this approach?


In our app we allow custom domains, so a user can create:  custom.my.example.com   Which we map to:  app.our.example.com   In our app we enforce SSL, except for when the user enters a preview URL such as this:  custom.my.example.com/preview/blah   Currently if users just type "custom.my.example.com" they receive an SSL error as the current rules only exempt /preview/blah from the forced redirect. How can I create a rule so that if a user enters "custom.my.example.com" without /preview it redirects them to  to show a special message?  Current .htaccess rules:  RewriteEngine On RewriteBase /  RewriteCond %{HTTPS} !=on RewriteCond %{REQUEST_URI} !^/preview RewriteCond %{QUERY_STRING} !^/preview RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]  RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule ^(.*)$ index.php?/$1 [L]   We are using CodeIgniter on CentOS 6.5 with Apache 2.2.  Thanks!

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.


For days now I've been trying to install Ubuntu along side windows 10 on my Dell laptop but failing. I was getting an errata error telling me to update the microcode. So after reading a few solutions I managed to update the Bios to the latest version. I also partitioned one of my hard drives (F) and allocated over 70GB. However I'm still failing to install Ubuntu alongside windows using a bootable USB stick. When I boot my machine from the USB, the process kind of starts but brings an error saying I need to update microcode, it then automatically skips that an continues to the next page where I'm to select to install or try Ubuntu. I click install, it goes ahead but when it reaches the menu where I should select "install along windows", that option isn't available. Instead I have like 3 options; Install Ubuntu and erase windows; and other options but doesn't give me the option to install along windows. Please help. How do I do about this?

Whenever I startup from the LinuxLive USB, and try to install Ubuntu 12.04, it only gives me two options instead of the usual 3 or 4. My options are "Replace Windows 7 with Ubuntu" and "Something Else". Whenever I go into "Something else", it looks extremely confusing. How do I install it side-by-side while using the "Something else" section? These are my partitions.   /dev/sda /dev/sda1 ntfs (104Mb, System Required Partition) /dev/sda2 ntfs (1000097Mb, Windows 7 Partition)   Or should I try reinstalling my installer on a CD rather than USB and maybe then it will have the "Install alongside" function?


Is the potential at each point on a circuit same,if so why? I have read that in order for current to flow through any kind of resistance,the potential of charges reaching resistance is higher than those exiting it. ie. all the charges before it are at same potential and the charges exiting it are at some low but same potential.this means that there are only two potential levels in a circuit. for better understanding of my doubt please check out this video

According to , if there is a potential difference, $V$, across a resistor then there is a current, $I$, flowing through it.   Since we assume that points along the connecting wire are at the same potential, how can current, $I$ flow between points at the same potential, $V$?


While I was trying to install wifi drivers in ubuntu 18.04, i was getting this error:  modprobe: ERROR: could not insert 'rtl8723be': Required key not available   I followed procedure given in   Unable to figure the reason for the error. Any solution to this problem will be appreciated.

The latest kernel for Ubuntu 16.04 (4.4.0-21) doesn't load the nvidia (and vboxdrv) module anymore.  $ sudo modprobe -v nvidia insmod /lib/modules/4.4.0-21-generic/updates/dkms/nvidia_361.ko  modprobe: ERROR: could not insert 'nvidia_361': Required key not available   With 4.4.0-18 it still works. What has changed? How do I fix the problem?


I have tried to change the way of citing multiple references from [1,2,3,4,5] to [1-5]. I have added a line \usepackage[style=numeric-comp]{biblatex}, but the references just turned from numbers to names of authors and I got a lot of warnings. Then I have deleted this new command and the document just got plenty of errors and can't be compiled. I guess that something happened to the way the references were defined before this new command.  Please help me to return my document compilation.

I ran into a strange problem while trying to implement a bibliography.  \usepackage[backend=biber,style=alphabetic]{biblatex} \addbibresource{Quellenverzeichnis.bib}   If style=alphabetic, a bibliography is printed and citations look for exmple like [BJS72]. As I rather want it to be author (year), I thought I need to change the style to "style=authoryear".  But the result is that the in-text citation is the full name of the article and no bibliography is printed. What am I doing wrong?  If it helps I could post my code but thats super long and I figured it might not really help as the only thing I'm changing is the style, I assume in the wrong way.   Thanks


I know it seems lame, but I'd like to have a function get access to its own name for printing error or debugging messages.  It would be easy then to have a standard way to start the printout:  print(__myname__,"is reporting the following..."   I prefer this to having to explicitly type the name each time because I often want to cut and paste such things, and I'd like any name change to be automatic, and thus more robustly correct.  This is similar to  but I want the name of the current function, not the name of its caller.  I note that the special name   __name__   in this spot is reporting the name of the package, not the name of the function.

In Python, how do I get a function name as a string, without calling the function?  def my_function():     pass  print get_function_name_as_string(my_function) # my_function is not in quotes   should output "my_function".  Is such function available in Python? If not, any ideas on how to implement get_function_name_as_string, in Python?


I already know how to prove that if the function $f$ has a right inverse, it implies that $f$ is surjective. But how can I prove that if $f$ is surjective it has a right inverse in a formal way?

Paraphrased from Munkres' Topology:     Lemma 9.2. Given a collection $\mathcal{A}$ of nonempty sets, there   exists a choice function   \begin{equation*} f: \mathcal{A} \to \bigcup\limits_{A \in  \mathcal{A}}A \end{equation*} such that $f(A) \in A$ for each $A \in  \mathcal{A}$.   Now consider  of the statement "$f$ is surjective iff it has a right inverse" as pictured below:    Instead of $S$, I am using $A$; and instead of $T$, I am using $B$.   Looking at the $f$ is surjective $\implies $ $f$ has a right inverse direction, we have this collection of preimages, $\{f^{-1}(\{y\})\}_{y \in B} = X$. The choice function given in the proof is $g: B \to A$. Shouldn't it technically be $g: X \to A$?  And is there not an abuse of notation throughout the proof as $y$ should be a singleton set? Especially in the last step?


Long ago in grade school we were taught the correct spelling WAS "Cancelled." When did they (spelling police?) decide it is "Canceled?" Personally drives me nuts. I dislike flying and try to avoid it. Being at a airport during heavy thunderstorms and seeing every board with flights that are "Canceled" trips my OCD. Spelling differences between US & UK, however, I find interesting.

I'm trying to figure out if there is a specific rule behind the word "cancel" that would cause "cancellation" to have two L's, but "canceled" and "canceling" to have only one (in the US).    I understand the rules are very loose when it comes to double L's in English, and I have read several posts on here talking about "canceled" and "canceling" (vs "cancelled" and "cancelling"), but my specific question is more about the spelling of "cancellation".    - they do NOT mention cancelation with one "L"  - they do seem to have cancelation listed with one "L" Microsoft Word marks "cancelation" as an invalid word Same with the spell checker in Firefox   So my question is: is there a reason or rule why in US English, "cancellation" seems to have two L's (to most dictionaries), while "canceled" and "canceling" does not?


ANS: Not sure how to do this. I wrote Induction: Prove P(K) = P(k+1) so assume P(k) is true. Statement = P(k+1) 1 + a + a^2 + a^3 + .... a^n-1 = 1-a^n/1-a = a + a + a^2 + a^3... a^k-1 = 1-a^k/1-a a + a + a^2 + a^3... a^k-1 + k + 1 = 1-a^k(k+1)/1-a ? I think I did this completely wrong

Possible Duplicate:          Proof to the formula  $$1+x+x^2+x^3+\cdots+x^n = \frac{x^{n+1}-1}{x-1}.$$


As I understand it, a company raises money by sharing parts of it ("ownership") to people who buy stocks from it.  I get that some stocks pay dividends, and that as these change the price of the stock may change accordingly.  I don't get why the price otherwise goes up or down (why demand changes) with earnings, and speculation on earnings.  So what if the company's making more money now than it did when I bought the share?  None of that is filtered my way as a "part owner".  Why should the value of the shares change?

So a company decides to raise money by selling shares of its stock. The stock is offered at an initial price of their determination. The stock is then traded in a market where forces of supply and demand, as well as speculation, affect its price.  When a company performs well (or makes decisions that will likely increase the company's earnings in the future), more people want to buy that stock than do people wanting to sell it. This creates demand for that stock which causes its sell/bid prices rise. When a company performs poorly, the opposite occurs; more people want to sell the stock than want to buy. This creates a surplus that causes sell/bid prices to fall.  Understanding this, people speculate over company performance to determine the future behavior of a stock, and attempt to "buy low, sell high" or "borrow high, return low" in order to make a profit.  But my question is regarding the first part of that process. What is it about company performance that causes the perceived value of its stock to rise? This is especially perplexing since I would guess that most people don't exercise their voting rights, and many stocks don't pay dividends.  It's not like a shareholder has any direct financial gains from increased company earnings (speculative stock pricing notwithstanding).  What is the intrinsic value of the stock?  It seems to me that all participants in a stock market tacitly agree that stock price will have a direct correlation with company performance. So another way of asking the question is, would an opposite agreement hold? What financially (this isn't a question about logistics, communication, or feasibility) stops all participants in a market from agreeing to value a particular company's stock inversely with respect to the company's performance?  Since I feel like I can't quite nail down my question, another form of it would be, why is stock market behavior driven by company performance?


I just go through books and the internet. But I didn't get my answer that, can I project light in the middle of the air, or wherever we want, not only on wall. I found neon lasers but it also didn't work.

Is there some law of physics that strictly prohibits the projection of 2D or 3D images into thin air (such as holograms in movies) or is a solution to achieve this still up for grabs by an eventual discoverer?


Let sequence $49,4489,444889,...$ is formed when in between digits $4$ and $9$ is the number $48$. For any number larger than $444889$ continue to put $48$.  Example: $49,4489,444889,44448889,...$ Prove that all numbers in the sequence are perfect squares.  I think of finding generating function of the sequence and then the closed form of a sequence.  How to evaluate generation function (in $\sum\limits$ notation)?

Prove that in a sequence of numbers $49 , 4489 , 444889 , 44448889\ldots$ in which every number is made by inserting  $48$ in the middle of previous as indicated, each number is the square of an integer.