So, I'm studying cosmology and my professor often uses the result $a=\frac{T}{T_0}$, but he never derived this relation and he just treates it as something intuitive... I think I can see how this would make sense, but I'd like to get a more formal understanding of it. Any light on this will be much appreciated. Thanks!

In all lectures, books and papers I have read about, the scale factor of the universe is inversely proportional to temperature  $$a \propto \frac{1}{T}$$  What is the reasoning behind this relation?  People did mention stretching of wavelength proportional to scale factor and wavelength being inversely proportional to temperature by Wein's law, but somehow this argument doesn't seem convincing to me. How did we initially come about to this relation?


what is the maximum salesforce id length? I have to communicate it to another system that has to create an ad hoc field

I remember seeing somewhere that IDs are composed of a few pieces. I always have a hard time trying to find that information when I'm looking for it. What I mean by the above is that the various places in the ID represent different things - for example the first few characters represent what type of sObject it is.


Let $n$ a natural number non zero   Prove that: $$n^5 \equiv n\mod 30$$  I have tried to use fermat theorem and little fermat i can't find any result

How can I prove that prove $n^5 - n$ is divisible by $30$? I took $n^5 - n$ and got $n(n-1)(n+1)(n^2+1)$ Now, $n(n-1)(n+1)$ is divisible by $6$. Next I need to show that $n(n-1)(n+1)(n^2+1)$ is divisible by $5$. My guess is using Fermat's little theorem but I don't know how.


Currently I am working on an assignment within BlueJ. The question I have is simple (I hope). The method I wish to use within the while loop is "getRearWheelDrive()" which checks how many Lamborghinis within the ArrayList< Lamborghini > inventory have rear wheel drive. rearWheelDrive is a boolean variable.   Also I can not use a for-loop for this question, otherwise I would as it would be much easier. I am limited to the while loop.  The error message I receive is: "non-static method getIsRearWheelDrive() cannot be referenced from a static context"  -I tried to create a  static method but it didn't work either.  //  How do I check all the Lamborghini objects within the ArrayList library and then return an int value of how many total have rearWheelDrive? Also with the current code I have, would it cause the loop to finish once it got to the end of the index, or would it infinitely loop?  public int howManyAreRearWheelDrive() {     int indexPlace = 0;     int number = 0;     int i = 0;      while(indexPlace <= inventory.size())      {         indexPlace++;         inventory.get(i);         i++;          if(Lamborghini.getIsRearWheelDrive() == true) {             number++;         }     }     return number;  }

The very common beginner mistake is when you try to use a class property "statically" without making an instance of that class. It leaves you with the mentioned error message:     You can either make the non static method static or make an instance of that class to use its properties.   Why? I am not asking for solutions. I would be grateful to know what is the reason behind it. The very core reason!  private java.util.List<String> someMethod(){     /* Some Code */     return someList;             }  public static void main(String[] strArgs){                // The following statement causes the error. You know why..     java.util.List<String> someList = someMethod();          }


I just got a new HP Probook 450 G2. One of the tasks I got it for, was to use Google Docs and google scripts. I've noticed when using Google script editor, on Chrome and Firefox,  My fonts are not looking right. The tops of the letters are funny. The equals sign is darker at the top than the bottom. I've had a play with font and cleartype settings and can't fix it.  Sorry am running windows 8.1 64bit  Any suggestions?  Firefox screen shot    Chromes screenshot

I experience a problem similar to    Here's a screenshot on the website     I've tried:   Removing fonts I have installed Setting the encoding to Western, UTF-8, Greek, Automatic Changing the fonts used in Google Chrome Removing Google Chrome, including all application data/user profiles Running CCleaner Reinstalling Google Chrome, twice Installing Chromium (fonts display fine in Chromium) Turning off Windows ClearType Changing Windows/Chrome languages from English (Australia) to US, UK Restarting Windows several times after making changes   All of which did not work. I do not connect over VPN/proxy.   Can anyone give me any tips?  Windows 7 x64 Ultimate


I want to replace the RAM within my computer to 4GB, it currently has 256mb of memory.  My question is what RAM is compatible with my motherboard?

If I want to add more RAM to my computer, how can I buy something compatible? What kinds are there? How do I determine which kind my computer will accept and how much I can add?


I've bought a N54L and fitted two 3GB drives. Keen to get set up with RAID1.   BIOS: SATA controller mode set to "RAID" RAID Option ROM utility: both physical drives set up as one logical drive   When I came to install Ubuntu (14.04.1), both drives appeared during the setup process. I was only expecting to see the logical drive, although I'm a complete novice with RAID.  I've read that the HP Proliant Microservers don't have "proper" RAID support, and require some kind of driver to be installed. I've tried a few HP utilities from the following apt repo:  deb http://downloads.linux.hp.com/SDR/repo/mcp wheezy/current non-free   On installation, most say "server not supported"  Would appreciate your advice.

I was trying to setup a Microserver with two 1TB harddrives as a software RAID. Somehow it didnt work and now ubuntu 14.04 is not starting. My problem is that I dont see the drives anymore when I go through the installation process again!  On boot I can see, that there are two working drives inserted, but I cant see them while being in the "partitioning menu" during the Ubuntu server installation.   There is no data on those drives, so I am looking for some way to erase them completely, so they show up again. From the installation I could switch to an Almequist (ash) shell.  How can I get my drives back?  Thanks!


I'm based in Germany, and the  is great for scheduling international train travel.  It knows all about the train times and connections all over Europe.  However, it rarely shows fares for trips which cross a border.  All the other national train operators' websites I've tried have the same problem.  This makes them rather useless for comparing prices when I've got a destination in mind and am trying to choose between, say, taking the train, flying, or renting a car...  or alternately if I've got a budget but no particular destination in mind, and would like to see what places I can afford to visit.  Is there any website which will let me plan train journeys in Europe, and give me the exact or even approximate fares?  (That is, something similar to the many flight search websites like .)

Is there a website to search for European train tickets? I mean something like kayak.com, expedia.com, airfare.com, etc for trains? I know there are specific countries' website like bahn.de, sbb.ch, voyages-sncf.com, etc. But is there a website to search and see the prices easily without having to go through many steps?


How can i Index my website? I have tried all things which google suggesting me still my website is not getting Indexed from last 30 Days?

It's been sometime and Google has yet to index my site. How can I get Google to index my website?


My netbook is an ACER AOD257. It has 1.66GHz, 1 GB of RAM and 320 GB HDD.  I am looking for the fastest Linux operative system on my computer. I have tried Lubuntu and I like it, but it is too much "cold" as operative system, then I have put Ubuntu; 12.04 LTS is the better version; is very fast and nice.  Nevertheless, I am facing another problem: my video card one is a half thunderstruck, 8 MB has gone to 128 MB, then inziavo to have problems also with Ubuntu 12.04 LTS because I had all the active effects.  Later I have passed to Ubuntu Mate 12.04, only that it gives me a problem, the audio is not heard... Then what operative System do you advise?  I would want it fast, nicely, lightly and very versatile. Has my friend advised me Ubuntu Studio, what do you think about it?

For a given hardware configuration, how do I find out if Ubuntu will run on it? What considerations should I take into account when choosing an Ubuntu version and  such as:    with a lighter desktop than the usual Gnome and Unity  with the even lighter LXDE desktop   Obviously Ubuntu does not run on some processor architectures. So how do I go about choosing the right version and derivate. How can I find out the minmal system requirements?


Does this file required an #include to define FooType? The function's type signature returns FooType* but the function implementation doesn't use FooType.  // test.cpp class FooType;  // Unresolved forward declaration  FooType* GetFoo() { return nullptr; }   It builds without warnings using g++ --std=c++11 -Wall. So is this a legal use of forward declaration?

I am looking for the definition of when I am allowed to do forward declaration of a class in another class's header file:  Am I allowed to do it for a base class, for a class held as a member, for a class passed to member function by reference, etc. ?


I'm basically a Web Developer(PHP Developer) by profession. I mainly work on PHP, jQuery, AJAX, Smarty, HTML and CSS, Bootstrap front-end web development framework.  I've also installed and using IDEs/editors like Sublime Text, NetBeans.   I'm also using Git repository for my website development as a versioning tool.  I'm using "Ubuntu 12.04 LTS" on my machine almost since last two years.   My machine configuraion is as follows:  Memory : 3.7 GiB Processor : Intel® Core™ i3 CPU M 370 @ 2.40GHz × 4 Graphics : Unknown OS type : 64-bit Disk : 64-bit   The important softwares present on my machine and which I'm using daily for my work are as follows:  PHP :  PHP 5.3.10-1ubuntu3.13 with Suhosin-Patch (cli) (built: Jul  7 2014 18:54:55)  Copyright (c) 1997-2012 The PHP Group Zend Engine v2.3.0, Copyright (c) 1998-2012 Zend Technologies   Apache web server :  /usr/sbin/apachectl: 87: ulimit: error setting limit (Operation not permitted) Server version: Apache/2.2.22 (Ubuntu) Server built:   Jul 22 2014 14:35:25 Server's Module Magic Number: 20051115:30 Server loaded:  APR 1.4.6, APR-Util 1.3.12 Compiled using: APR 1.4.6, APR-Util 1.3.12 Architecture:   64-bit Server MPM:     Prefork   threaded:     no     forked:     yes (variable process count) Server compiled with....  -D APACHE_MPM_DIR="server/mpm/prefork"  -D APR_HAS_SENDFILE  -D APR_HAS_MMAP  -D APR_HAVE_IPV6 (IPv4-mapped addresses enabled)  -D APR_USE_SYSVSEM_SERIALIZE  -D APR_USE_PTHREAD_SERIALIZE  -D SINGLE_LISTEN_UNSERIALIZED_ACCEPT  -D APR_HAS_OTHER_CHILD  -D AP_HAVE_RELIABLE_PIPED_LOGS  -D DYNAMIC_MODULE_LIMIT=128  -D HTTPD_ROOT="/etc/apache2"  -D SUEXEC_BIN="/usr/lib/apache2/suexec"  -D DEFAULT_PIDLOG="/var/run/apache2.pid"  -D DEFAULT_SCOREBOARD="logs/apache_runtime_status"  -D DEFAULT_LOCKFILE="/var/run/apache2/accept.lock"  -D DEFAULT_ERRORLOG="logs/error_log"  -D AP_TYPES_CONFIG_FILE="mime.types"  -D SERVER_CONFIG_FILE="apache2.conf"   MySQL :  5.5.38-0ubuntu0.12.04.1   Smarty :  2.6.18   **NetBeans :**  NetBeans IDE 8.0 (Build 201403101706)   Sublime Text 2 :  Version 2.0.2, Build 2221   Yesterday suddenly a pop-up message appeared on my screen asking me to upgrade to "Ubuntu 14.04 'Trusty Tahr'". I'd also be very happy to upgrade my system to "Ubuntu 14.04 'Trusty Tahr'".  Following are the issues about which I'm little bit scared about and I need you all talented people's expert advice/help/suggestions on it:    Will upgrading to "Ubuntu 14.04 'Trusty Tahr'" affect the softwares I mentioned above? I mean will I need to re-install/un-install and install these softwares too? Do I really need to and is it really a worth to upgrade to "Ubuntu 14.04 'Trusty Tahr'" from "Ubuntu 12.04 LTS"  now? If I upgrade to "Ubuntu 14.04 'Trusty Tahr'" what advantage I'll get from web developer's point of view? Will the upgrade be hassle free and will I be able to continue my on-going work without any difficulties? Is "Ubuntu 14.04 'Trusty Tahr'" a LTS version and if yes till when it's going to provide support?   These are the five crucial queries I have. If you want any further explanation from me please feel free to ask me.  Thanks for spending some of your vaulable time in reading and understanding my issue.   Any kind of help/comment/suggestion/answer would be highly appreciated. Though if someone gives canonical, precise and up to the mark answer, it will be of great help to me as well as other web developers using Ubuntu around the world.   Once again thank you so much you great people around the globe.  Waiting for your precious replies.

I just installed Ubuntu 12.04 LTS about 2 weeks ago. A week later a newer LTS came out. Now I know that I will get to upgrade in June but I don't know if I should upgrade or not. Please give me suggestions.


At the end of  (2008), Mademoiselle (Catherine Bégin) asks torture victim Anna (Morjana Alaoui) whether she has or has not witnessed Otherworld, and the answer is enough to make a 70-something, devoted, calm, focused, cold blood, cruel and emotionless person shoot herself in the head.  Any idea what she said?

After watching Martyrs (2008), I kept on thinking about the motive or the message behind that movie. My question is, why was the skin peeled off the entire body of that girl, and what did she tell to the old woman which led the woman to commit suicide?


For a few days I was using a computer with a wrongly set clock (without realising) and made a bunch of commits that now have the wrong timestamps. I'd like to know if it's possible to bring these timestamps forward by a set amount (2 weeks).  The commits are all sequential and I've already pushed them to Github.  I presume I'd need a script to do this (if it's possible at all) but I don't know where to start.

The answers to  describe a way to amend previous commit messages that haven't yet been pushed upstream.  The new messages inherit the timestamps of the original commits.  This seems logical, but is there a way to also re-set the times?


Can anyone here help me about my title problem in google?  My title in google result page do not exact match with my title tag. If you search with keyword "itclax furidacchi" in google, my title there is a anime word. Im not use anime word in my title. I dont know what must i do again, i inspect element doesnt work, nothing anime word in my element site.!    NB: one of author make my question is duplicated, but i cannont resolve my problem with read duplicate post.

I'm just wondering how it is possible that IGN.com has this in its title tag:      Video Games, Cheats, Walkthroughs, Game Trailers, Reviews, News, Previews & Videos at IGN   while on Google its title is simply "IGN".   How can one achieve such a thing? Does it use some special meta tag I can't see?


Let $X$ be a standard normal random variable. $P(X)$ gives the   probability density function of $X$. Let $Y$ be a random variable   independent of $X$ and takes values $-1$ to $1$ with $P (Y = 1) =  0.5$. Define a new random variable $Z: = XY$.       What is the probability density function of $Z$?

Let $X\sim N(0,1)$ and let $Z$ be a random variable independent of $X$ such that:  \begin{equation} \Pr(Z=z) = \begin{cases} \frac{1}{2} & \mbox{if $z = -1$ or $z=1$}, \\ \\ 0 & \mbox{otherwise}. \end{cases} \end{equation}   Define $Y = ZX$. Show that $Y \sim N(0,1)$. Determine $\operatorname{Cor}(X,Y)$. Are $X$ and $Y$ independent?   Progress:  I'm basically stuck at the beginning. I got as far as $P(ZX < y) = P(Z < y/X)$, which I'm not even sure is correct. I'm also not clear on what it means by defining $Y = ZX$ - does it mean I need to state the probability density function or something? And how do I show that $Y \sim N(0,1)$?


What can you call a person who is cunning but depicts themselves as innocent to others?

This is not from real life, but from a movie on my local TV. A character in the movie is really bad, but when she talks with others, she pretends to be an innocent/ good woman. I want to know how to describe this kind of person.


package com.francesco.provadinuovo;  import android.os.Bundle; import android.support.v7.app.AppCompatActivity; import android.view.View; import android.widget.Button;  public class MainActivity extends AppCompatActivity {      Button button;     @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);          setContentView(R.layout.activity_main);        button =(Button) findViewById(R.id.button);          button.setOnClickListener(new View.OnClickListener() {              @Override             public void onClick(View v) {                 System.out.println("Welcome!");              }         });     } }   the problem is: 02/18 14:32:30: Launching MainActivity $ adb push C:\Users\start\AndroidStudioProjects\Provadinuovo\app\build\outputs\apk\app-debug.apk /data/local/tmp/com.francesco.provadinuovo $ adb shell pm install -r "/data/local/tmp/com.francesco.provadinuovo" Success  $ adb shell am start -n "com.francesco.provadinuovo/com.francesco.provadinuovo.MainActivity" -a android.intent.action.MAIN -c android.intent.category.LAUNCHER Client not ready yet..Waiting for process to come online Connected to process 2354 on device emulator-5554 W/System: ClassLoader referenced unknown path: /data/app/com.francesco.provadinuovo-1/lib/x86 W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable I/OpenGLRenderer: Initialized EGL, version 1.4 D/OpenGLRenderer: Swap behavior 1 E/EGL_emulation: tid 2445: eglSurfaceAttrib(1146): error 0x3009 (EGL_BAD_MATCH) W/OpenGLRenderer: Failed to set EGL_SWAP_BEHAVIOR on surface 0x971ec920, error=EGL_BAD_MATCH

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


I had Catalina OS on my Macbook, but I was needed to reinstall OS. So I make a restart hold Command + R (Mac utility was opened), so I erase all data and reinstall OS. But when I reinstall OS, there is was not choice which OS I would like to install and Mountain Lion 10.8 was installed.  Now, I would like to upgrade this OS version to Catalina like it was before...  But I can't, I get message from AppStore that I need to have 10.9 OS version or  later.   So, as far as I understand I need to install any intermediate OS version like El Captain or Mavericks and just than get update to Catalina, right?  But issue is, that Mavericks no longer supported by AppStore , but I found link to El Captain, but I also got a message that this version can't be installed...  What to do? How can I get update?  Feel free to ask

Sometimes it's hard to search for older versions of macOS & OS X  on the App Store.  This is an attempt to provide the canonical QA for this issue, as per the Meta QA -  I expect it to be modified over time to hopefully become a complete information resource.  How can I get any older version of a Mac OS to be able to run as a VM, or to reinstall on my Mac?


For an adult (age 24yrs), is it legal to drive using learner's permit from TX in OR state?

Do states have any kind of reciprocal agreement for drivers (learner's) permits?  If a child has a learner's permit issued in one state (i.e. Virginia), can that child legally drive in a second state (i.e. South Carolina)?  My specifics: we're taking a family vacation to Myrtle Beach, SC from Stafford, Virginia. My son has a Virginia Learner's Permit. Will he be able (legally allowed) to drive my car in SC?


The action:  $$J=∫Tr(F∧⋆F).$$  Is it possible to find the non-mass gap property from the Yang mills action? If so, how?

Ref:   Can anyone please explain why the Yang–Mills Existence and Mass Gap problem is so important / fundamental to contemporary mathematics (and, presumably, theoretical / mathematical physics)?  If possible, please include the following in your answer / response:  (1) Why the problem is so fundamental / important - for both mathematics and theoretical / mathematical physics; (2) How the solution to the problem would impact research in the above two fields; (3) (If applicable) What progress has been made so far in resolving it; (references to papers, books, other resources would be helpful).  I'm an upper-level undergraduate in theoretical physics, and so am seeking an answer / response at such level.


constructor have signature:  GregorianCalendar(int year, int month, int dayOfMonth) GregorianCalendar(int year, int month, int dayOfMonth, int hourOfDay, int minute, int second)    What happen if I pass month or dayOfMonth out of constructor contract?  It is easy to check if month in 0-11 range. But it is impossible to check valid day (which should be  28/28/30/31?) without writing own Calendar implementation.  It should be nice if Java Platform checks user date input. I don't like to check if 2015-13-32 is valid ISO date in own code.

I find it curious that the most obvious way to create Date objects in Java has been deprecated and appears to have been "substituted" with a not so obvious to use lenient calendar.  How do you check that a date, given as a combination of day, month, and year, is a valid date?  For instance, 2008-02-31 (as in yyyy-mm-dd) would be an invalid date.


I have just got the "" Hat.Isn't that a bit early as I am in GMT and the time is 1310.  Or do we get then whenever it is Dec 25 anywhere?

I just got the  hat which states "post or vote on December 21".  Does SE have a time machine now?


I checked my Gmail on a friend work computer, whose company also has a work Gmail account. Now when either of us login to email, part of the other person's name appears. This is frustrating for me since my Google photos are linked to Gmail. Doubly frustrating for him because it's a work computer. Any advice would be greatly appreciated.

When signing in with Google (OAuth), it shows a list of accounts it already knows about. How can I remove some accounts from this list?    I know I can nuke all of them by deleting all cookies, but I'd prefer to remove one account that I don't want there, rather than all of them.  There used to be an ability to edit this list in the older version of this screen, but in 2018 redesign Google has removed [×] buttons next to the accounts.


So, I'm trying to make only
text
 aligned vertically and horizontally to the body of a page with the body's css set to be 100% width and height.  I don't want it to be a div. ONLY h1 within a

Best way to center a <div> element on a page both vertically and horizontally?  I know that margin-left: auto; margin-right: auto; will center on the horizontal, but what is the best way to do it vertically, too?


I am trying to prove the following:     Every nonempty $X \subset \mathbb N$ has an $\in$-minimal element.   Proof: Take some $n \in X$. Then $\min \{ n \cap X \} = \min \{ X \}$.  Is this ok or should it be more detailed?

Is there anything wrong with the following proof?  Theorem. Every non-empty subset $B \subset\mathbb{N}$ has a least member.  Proof. Assume not. Then, of necessity, we'd have to have $B=\varnothing$, for if $B$ contained even one $b\in\mathbb{N}$, then that $b$ would satisfy $b=min(B). $ Contradiction, end proof.  I get the sense there is something wrong here, but I can't seem to define exactly what. Also, is there a context where one can simply take this principle as an axiom, and not have to prove it? After all, it is extremely intuitive. Thanks.


I have studied calculus and a bit of linear algebra. And now, I'm finding a book about analysis, which I can self-study. Can anyone recommend me a good analysis book which has many examples, and is compact?

Does anyone have a recommendation for a book to use for the self study of real analysis? Several years ago when I completed about half a semester of Real Analysis I, the instructor used "Introduction to Analysis" by Gaughan.   While it's a good book, I'm not sure it's suited for self study by itself.  I know it's a rigorous subject, but I'd like to try and find something that "dumbs down" the material a bit, then between the two books I might be able to make some headway.


In Indian English, it is widely used as "I have a doubt with .....". While in America English, it is used as "I suspect there is a problem with...".  What is the conceptual difference between these two? Which is recommended/correct way to use?

I often see questions on Stack Exchange sites which I presume are written by non-native English speakers who use the word "doubt" in place of the word "question". Is this a case of misunderstanding the correct meaning or are people being taught that this is correct usage?


I'm writing a book, and I don't know if I'm using the word peoples right. I'm fairly sure it IS a word, but I don't know its exact use.

Can you please clarify the relation and differences between these nouns?   For example, is it proper to use "persons" instead of "people"? Are they the same? As I believe that "people" is plural, how come there exists the plural of the plural (=peoples)? Does it have any usage?


From the AsyncApexjob object, I am unable to get the scheduled start time of a job. Is there a way to get the start time of a apex job.

How to access Submitted date of apex jobs because it is not a standard field of asyncapexjob ?


I have recently gotten interested in cryptography, so I looked some things up.  I thought, why even use AES or DES or any other complex way for encrypting data when there are far simpler ways, like just generating a random (pseudorandom) bitstream, and XOR'ing it with the data or secret message? The point is, if you have a random enough bitstream, you can just XOR the data.   Of course, you're the only one who will know the stream.  So why use all sorts of encryption if you have these simpler, easier ways of doing things? I'm new to cryptography, so this question may sound a bit naive.

RSA, DES, AES, etc., all use (relatively) complicated mathematics to encrypt some message with some key. For each of these methods, there have been several documented vulnerabilities found over the years. Some even believe that there is a vulnerability in AES known only to the NSA.  On the other hand, the one-time pad is not only ridiculously simple, but also has been shown to be impossible to crack (if used appropriately).  Say you have some message to be encrypted with length n. Simply generate a random string with length m where m is at least as large as n, and perform modular addition of the random string onto the message.  As long as the random string is generated with a high-enough-quality random number generator, and as long as the same one-time pad isn't reused, it should be impossible to crack.  If this is true, all we would need to perfect are fast, cryptographically secure deterministic random number generators. Use the key as a starting seed for the RNG and you have a powerful uncrackable encryption scheme which is simple to understand and implement.  Blum-Blum-Shub is a fast, cryptographically secure PRNG, and there are others too.  I have written a C++ program which uses two 2048-bit primes (which match the necessary criteria) for Blum-Blum-Shub and uses a password which the user enters - converted into a starting seed - to run byte-wise modular addition. The process is fast, deterministic, and if the literature I have read is correct then it should be very secure.  So why is so much time and effort invested in coming up with convoluted encryption cyphers when mathematics shows that the simplest is often the best?


I have a big .gz file, which is 2.6 GB in itself. I cannot uncompress it due to size limitation. The file is a single large text file. I am not being able to decompress it completely due to size limitation. I want to split it into say 10 individual parts and decompress each one individually so that I can use each individual files:  My questions are:   Is that possible ? Also, as part of the answer, if the commands can also be provided as I am not very well versed in these commands   Thanks

I have a big .gz file. I would like to split it into 100 smaller gzip files, that can each be decompressed by itself. In other words: I am not looking for a way of chopping up the .gz file into chunks that would have to be put back together to be able to decompress it. I want to be able to decompress each of the smaller files independently.  Can it be done without recompressing the whole file?  Can it be done if the original file is compressed with --rsyncable? ("Cater better to the rsync program by periodically resetting the internal structure of the compressed data stream." sounds like these reset points might be good places to split at and probably prepend a header.)  Can it be done for any of the other compressed formats? I would imagine bzip2 would be doable - as it is compressed in blocks.


I have always wanted to know the answer to this question (sorry if it's silly):  If a professor or lecturer answers a question or gives advice when replying to an email I sent them, in general, do they prefer if I send them a one-line email saying 'thank you!' or no email at all? If I send a one-line email I'm worried I'm just clogging their inbox, but if I don't send any email at all, I'm worried I'll seem cold/selfish.  Thanks in advance!

A very busy professor just responded my email. He answered my questions, and in the end, he explicitly said something like "Please let me know if you have any questions" or "Please respond if you have further questions".  So, I am trying to think as if I am in his shoe. Is he not expecting me to reply to this email, if I do not have any further questions?   Is it impolite if I do not respond to this email and let it go? Or, is it considered impolite if I spam his "already-too-full" mailbox with a generic "Dear XXX, Thanks for XXXXX, Regards, XXXX" ?


I didn't like Anna calling Tom a bad person. However, most of the boys   in our class shared her view;/: Tom often bullied others, always   mocked the weak, and stole stuff from time to time.   Should that be a colon or a semicolon? And why?

From Grammar Workshop: "Lydia's father is a master chef he oversees the kitchen at a five-star restaurant."   Can someone explain whether to use a semicolon or a colon?


In Einstein's thought experiment involving light moving on a train, the mirrors the light is bouncing between are perpendicular to the train, and it is these mirrors that the formula for time dilation is based on. But if the mirrors were positioned differently - for example at angle of 30 degrees to the side of the train or in the direction of the train's motion - wouldn't the formula be different? My calculations tell me it would be. So I don't understand how this formula applies to everything in the train no matter what direction it's moving in.

Many texts about STR time dilation use as an example thought experiment with  The conclusion of this experiment is: In a frame moving relative to the clock, they will appear to be running more slowly. As I understand it, this is just a visual effect, it doesn't mean that processes in the system with clocks are affected by someone observing it from moving frame. I can't imagine any other interpretation of this, cause this would result in all sorts of paradoxes, like what if there are 3 clocks oriented: parallel, perpendicular and at 45 degree relative to direction of moving frame. If you visualise light path from moving frame perspective like it is done in wiki link above, and do analogical interpretation, this would imply that some of the 3 clocks in same frame are running slower and some are faster, depending on orientation.   According to the same wiki page this time dilations are not just visual effect and do change behavior of objects, here is a quote from 2nd paragraph:     Such time dilation has been repeatedly demonstrated, for instance by small disparities in a pair of atomic clocks after one of them is sent on a space trip, or by clocks on the Space Shuttle running slightly slower than reference clocks on Earth, or clocks on GPS and Galileo satellites running slightly faster.   So if we continue our analogy, we can take 4 pairs of atomic clocks, and send 3 of them on a space trip oriented differently, we would get different time results on them.  We can even continue this absurd, and remind "twins paradox", and conclude that the one that was perpendicular to moving frame would become older....


this might be a (very) stupid question, however I need to ask it (why?). I have the congruence $84x ≡ 68$ $(mod$ $400)$ from: , where the solution is given. However, I tried to solve this using the Chinese Remainder Theorem and got the wrong answer. So my question is, can I use CRT to solve this and if so please provide an answer, if I can't use CRT why not, what condition is not fullfilled?  Ok, I might not have been clear. When applying CRT I get: Primefactorization of $400 = 2^4*5^2$ then:  $84x ≡ 68$ $(mod$ $2^4)$ ↔ $4x ≡ 4$ $(mod$ $2^4)$ ↔ $x ≡ 1$ $(mod$ $2^4)$ $(1)$ $84x ≡ 68$ $(mod$ $5^2)$ ↔ $9x ≡ 14$ $(mod$ $5^2)$ ↔ $x ≡ 21$ $(mod$ $5^2)$ $(2)$  From (1) and (2) I get: $x = 1 + 16s ≡ 21$ $(mod$ $25)$ → $s = 20 + 25*t$ → $x = 321 + 400t$ which is wrong :(  Where am I going wrong?  Regards

I reduced the equation:  $84x \equiv 68\mod 400$  $21x \equiv 17\mod 100$  $100 = 4 \times 21 + 16$  $21 = 1 \times 16 + 5$  $16 = 3 \times 5 + 1$  so we have...  $16 = 100 - 4 \times 21$  $5 = 21 - 1 \times 16$  $1 = 16 - 3 \times 5$  Now, I need the equation in the form of $21v + 100w = 1$ and I have to find v and w  $1=16-3 \times 5$  $=16-3(21-1 \times 16)$  $=16 - 3 \times 21 +3 \times 16$  $=100 - 4 \times 21 -3 \times 21 +3 \times 16$  At this point I don't know what to do. Please help.


This is a response to the following exchange at    [Bill constructs a $\aleph_0$ linearly independent set in $\Bbb R$]  Can you extend the idea of this proof to get the right dimension? Currently, you only have a countably infinite independent set, but the dimension is size continuum. –   I believe the answer to this question is no, for the following reason. Suppose we have a spanning set for $\Bbb R$ over $\Bbb Q$, of cardinality $\frak n$. Then by definition we have the cardinality equation ${\frak c}\le^*[{\frak n}]^{<\omega}\cdot \aleph_0$ (where $[{\frak n}]^{<\omega}$ is the cardinality of finite subsets, and $\frak m\le^*n$ means there is a surjection from $\frak n$ to $\frak m$). If $\frak n$ is finite, then we get ${\frak c}\le^*\aleph_0$ which is false, so $\frak n$ is infinite (but not necessarily Dedekind-infinite). If we assume the axiom of choice, then the equation reduces to $\frak c\le n$, hence every Hamel basis is size continuum. But without AC I don't know any way to simplify the original equation to get anything stronger than "$\frak n$ is infinite". This is at best heuristic evidence for the original question, since it is considering a different problem (spanning sets instead of linearly independent sets). How could one show that there are no ZF-constructible $\Bbb Q$-linearly independent subsets of $\Bbb R$ of cardinality continuum?

Does there exist an uncountably infinite set $X \subseteq \mathbb R$ such that $\mathbb R \neq \left<X\right>$? I can't think of any, but I'm also having trouble trying to prove that no such subset exists.  For example: $\mathbb R$ is uncountable and obviously $\mathbb R = \left<\mathbb R\right>$. The Cantor set $C$ is uncountable, and we know that $C - C = [0, 1]$, so then since $\mathbb R = \left<[0, 1]\right>$ we know that $C$ also generates $\mathbb R$. Also the set of irrationals $\mathbb R \setminus \mathbb Q$ is uncountable, but we can generate all the rational numbers by fixing one irrational number $\alpha$ and then saying the any rational number $x$ shall be $(\alpha + x) - \alpha$, since both $\alpha + x$ and $\alpha$ are irrational.  So the examples that quickly come to mind all generate the reals. Is there a simple counterexample?


This is my source code of a LaTeX file, I use the package CJK in the editor WinEdt, and MiKTeX, but the display result is bad, it cannot display Chinese characters.  \documentclass[12pt]{article} \usepackage{CJK} \title{Test} \author{zhulongsheng(11291065@bjtu.edu.cn)} \date{2014/01/28} \begin{document} \maketitle \begin{CJK*}{GBK}{song} \today \section{第一} 这是第一段 \CJKfamily{hei} \section{第二} 这是第二段 \subsection{Goal} 这是 \LaTeX \end{CJK*} \end{document}

Can anyone describe how one can type Chinese in LaTeX? When I compile this:  \documentclass{article} \begin{document}  你好吗？ \end{document}   the resulting document shows nothing. For reference my IME is iBus 1.3.9 on Fedora 13.


I am currently self-studying number theory in high school, and came across this question:     Assuming that for every integer $n>1$, there exists a prime number between $n$ and $2n$, prove that every positive integer can be written as a sum of distinct primes or $1$ more than a sum of distinct primes.   My attempt:    We use induction on $\Bbb N$.  Clearly, $1$ can be written simply as $1$, thus the conjecture is true for $1$. We assume that the conjecture is true for all numbers up to some $k\in \Bbb N$.  Now, we take $k+1$ and find out $\Bigl \lfloor \frac{k+1}{2} \Bigl \rfloor.$ By Bertrand's Postulate, there must exist primes between $\Bigl \lfloor \frac{k+1}{2} \Bigl \rfloor$ and $2\Bigl \lfloor \frac{k+1}{2} \Bigl \rfloor$, where $2\Bigl \lfloor \frac{k+1}{2} \Bigl \rfloor \leq k+1.$ By the well-ordering principle, the set of primes has a least element, say $p$. We find out $(k+1)-p$.  Now by our induction hypothesis, the number $(k+1)-p$ can be written as the sum of distinct primes, none of them $p$ since $p>(k+1)-p$. Let them be $p_1, p_2... p_n$.  Thus we can write   $$k+1=p+p_1+p_2+...+p_n$$  which concludes our proof.    Is the proof correct? Is there a better way to do it? I have a distinct feeling that it is possible to do this through a proof by construction, in which we find the primes through a similar argument.  Edit: My question is not a dupicate because the other question's top answer is not clear enough and only provides a hint. The other answers are not satisfactory.  Further, this is a proof verification question, and my final statement 'can this be proved by a proof by construction' is not addressed in the other question.

Let $\Bbb{P}$ be the set of prime numbers and $Q=\Bbb{P}\cup\{1\}$. Is it true that every natural numbers ($\neq 0$) is the sum of distinct elements of $Q$? I tried from $1$ to $60$ and it seems true.


I'll tell you the story of how I started to notice the problem with my PSU. I was just playing some minecraft, just doing my thing when I started to hear a strange buzzing noise from my PC. So i opened it up to so what was up. I couldn't clearly hear where the noise was coming from. So I took off both of the side panels and heard it was coming from the PSU.  After this I started looking up online for what this might be. At this point I should tell you my hardware. I'm running an RTX 2080 and I5-9600k with my PSU being a 750W MasterWatt from coolermaster.  I came across this post from Dante R.    I thought, hey this guy has the same GPU as me. He might have the solution. But in his post the problem was with the GPU, not the PSU. So I went back to checking if it indeed was my GPU. But after listening closely I could clearly hear it was coming from my PSU. (Which is why I posted this Question since the other post was fixed by fixing the GPU)  Here is a video so you can get an idea of what it sounds like.   Afterwards I did some testing as to why it only started when I was playing Minecraft. I loaded up Prime95 to do some CPU stress testing... no noise. I launched up Heaven Benchmark... As soon as my GPU started doing it's thing, the noise came back! So it has something to do with GPU aswell.  From what I read I think it may have something to do with Coil Whine. And if so,can it be dangerous for my PC and how can I stop it?  So I'm looking for any advice you lovely people can give me on how to stop this problem.  Thanks in advance!

Ok so this is a weird one. I'm used to troubleshooting things like this one myself, but now i'm rather stuck.  Just bought a new PC with RTX 2080 & Ryzen 7 2700X. All good, runs smooth and rather cool. While gaming i have heard a weird buzzing noise coming from my PC. I tried to locate the sound and it seems that it might be coming from the PSU (all components are new).  Here comes the weird part: I tried reproducing it instead of having it show up randomly by stress testing my CPU and GPU at the same time. I figured if its a PSU problem while gaming then it should show up while stress testing (especially since no game has challenged my CPU & GPU at the same time so far). Ran it for about 10-15 minutes. No buzzing.  The noise can also be heard very briefly (and at a lower volume so to speak) randomly. Last night i was watching a movie, it heard a low buzz and its not the first time. Now i'm in a game (ATLAS) and SOMETIMES it starts buzzing.   Any tips on how i could troubleshoot this ? All temps are fine, no PC freeze, no BSOD, no errors at all of any kind, yet the buzzing sound is there.  I must add that i  just bought a UPS because i needed it and i also thought it might be because of my houses electricity "bouncing" (not very good at electrical stuff). Nothing changed.   I also managed to record it here ->   You can also hear the fans, but the sound cant be missed (also a bit louder since i was recording near the source).  Any tips? Thanks!  P.S: Not sure if the hardware-failure tag is fine since nothing failed so far, but i'm unsure what to use.  Edit: Forgot to mention, i checked task manager while in-game when it started buzzing.  Nothing was even near 100% and my HDD was at 1% (the one the game is on).   Edit2: Added voltages.   Edit: Finally found the source of the buzzing! Its the GPU, but its not a fan. I think its the GPU case that is buzzing. After 3 days i managed to get the buzzing while my case panel was off. I tried slowing down one of the fans, the buzzing stopped while my finger was slowing the fan. Then i tried another fan, same thing. And then FINALLY i simply touched the plastic case on my GPU and the same outcome -> buzzing stopped.   From this i assume my GPU case is actually buzzing due to FAN vibrations ? My card doesnt seem to be 100% in place in the PCI slot (its rather big), but i dont think that has anything to do with it (its a not a perfect line so to speak). Any tips on how to fix the buzzing now ? I'm attaching a picture of my GPU for ref.     You can see that its not perfectly aligned if you look at the MB port. By touching the case and it stopped i mean the grey case part on the GPU that you can see in the pic (bottom of GPU).


How can I get rid off my mouselag under Ubuntu 16.04?  The lag is not related to firefox or a webbrowser. Graphic card is regognized correctly.  nuc@nuc:~$ sudo lshw -c video [sudo] password for nuc:    *-display                       description: VGA compatible controller        product: Haswell-ULT Integrated Graphics Controller        vendor: Intel Corporation        physical id: 2        bus info: pci@0000:00:02.0        version: 09        width: 64 bits        clock: 33MHz        capabilities: msi pm vga_controller bus_master cap_list rom        configuration: driver=i915 latency=0        resources: irq:45 memory:f7800000-f7bfffff memory:e0000000-efffffff ioport:f000(size=64)

I experience mouse lag although the graphic card is recognized by the os. (I already had it on 15.10 and upgraded to 16.04). The mouse lag is not firefox or browser dependent. Is there anything I can do about it, without doing a clean install of my ubuntu system?  nuc@nuc:~$ sudo lshw -c video [sudo] password for nuc:    *-display                       description: VGA compatible controller        product: Haswell-ULT Integrated Graphics Controller        vendor: Intel Corporation        physical id: 2        bus info: pci@0000:00:02.0        version: 09        width: 64 bits        clock: 33MHz        capabilities: msi pm vga_controller bus_master cap_list rom        configuration: driver=i915 latency=0        resources: irq:45 memory:f7800000-f7bfffff memory:e0000000-efffffff ioport:f000(size=64)


Question: I want to show that every algebraic extension of a finite field $F$ is separable. Thoughts: I think I know how to do this: let $F\subseteq E$ be an algebraic extension of $F$.  Let $a\in E$.  Then there is some $f(x)\in F[x]$ irreducible such that $f(a)=0$.  So, $f(x)=c_nx^n+\dots +c_1x+c_0$ where $c_i\in F$, $n\in\mathbb{N}$, $c_n\neq0$.  So, $f'(x)=nc_nx^{n-1}+\dots +c_1$.  Then we consider if $f'(x)=0$ then $(f(x),f'(x))=1$ so $f(x)$ is serpable, and if $f'(x)\neq0$ then I'm going through and eventually getting a contradiction to $f(x)$ being irreducible, thus finishing my proof.  However, it takes about a half of a page to get that contradiction and I was wondering if there was maybe a shorter, or less computational, way of proving this.  Thank you so much!

I'm trying to prove that every finite extension of a finite field is separable. I found a solution on internet which says:     Let $F$ be a finite field and $E$ be an extension of $F$ having  $p^n$   elements. Then $E=F(\alpha)$, where $\alpha \in E$ and so   $\alpha^{p^n} -\alpha=0$. This implies $\alpha$ is a separable   element, and hence $F(\alpha)$ is a separable extension of F.   I don't understand why $\alpha^{p^n} -\alpha=0$ and why $\alpha$ is a separable element, I need help.  Thanks


The Earth is rotating for the Sun's gravitational field. Like a free falling object Earth should feel zero gravity to the Sun. So why there are effect of Sun to the tide?

As I understand, satellites and the Moon orbiting Earth are in free fall. Isn't the same true for Earth orbiting the Sun?  My question is then: How can the Sun's gravity affect ? Aren't the molecules in the oceans in free fall relative to the Sun?


Ok, here is what I think. Please correct me if I am wrong. $$\sqrt{9} \neq 3$$ and also $$\sqrt{9} \neq -3$$  Now let's assume, that above statements are false, then we have $-3 = \sqrt{9} = 3$ and since $3 \neq -3$ the assumption must be wrong. Ok, square root must be equal to 3 and -3 at the same time. As of my understanding a set of numbers is not a number itself and that leads to a conclusion, that a square root of a number is not a number. Right?  Both answers are of the same importance - neither of them is superior. Then here is the question - when we plot $f(x) = \sqrt{x}$, why do we always plot positive answers? Can someone give me a proof, that plotting negative answers is not allowed?

It is perhaps a bit embarrassing that while doing higher-level math, I have forgot some more fundamental concepts. I would like to ask whether the square root of a number includes both the positive and the negative square roots.  I know that for an equation $x^2 = 9$, the solution is $x = \pm 3$. But if simply given $\sqrt{9}$, does one assume that to mean only the positive root? And when simply talking about the square root of a number in general, would one be referring to both roots or just the positive one, when neither is specified?


This is not a question about upgrading to windows 10!   I have read many times that in windows 10, you cannot disable automatic updates, which means windows 10 will download updates automatically whenever it is available. Doesn't Microsoft know that this change would negatively affect people like me who have limited bandwidth and pay higher price for data? (This is almost true for people in developing countries). Is there any response from MS about this? Does MS really considered these people when they released their new OS in 150+ countries?    Is there any workaround for this?

We've upgraded some machines to Windows 10 and realized there were some updates which updated as required. However, I realized there was no option available to stop the download similar to that on Windows 7 and 8.1. The only way I could stop the download was to stop the Windows Update service.  My question is does anyone know of a way to stop auto updates or is stopping the service is the only solution?


It is known that raises to a certain height based on the parameters of surface tension, the radius of the tube, etc. Given by the formula $$h=\frac{2S\cos \theta}{\rho Rg}$$ When the capillary tube is of insufficient height I'm told the water does not overflow and read  which prove this using energy. But why can't water be pulled by the surface tension on the interface outside of the tube? Resulting in all the liquid emptying out like a siphon.

Suppose we have a capillary tube in which water can rise to a height of x cm. If we dip the tube such that the height above the surface is less than x, then how will the water meniscus be at the edge of the tube? Why?    Excuse the flat water at the surface near the base of the capillaries.  EDIT: @NewAlexandria Here's my reasoning.  A is the most likely case as once the water molecules at the inner circumference reach the edge, they cannot go any further up as there is no glass to give the needed normal reaction (cosine component). That's all I can think of.


I need to program a code that gives the user an equation if the user solves it a promo code will be given.  1, I need to make the random number from 1 to 9 only.  2, No "random" number displayed in JOptionpane:(!  3, I also need the promo code to be a random number too that contains more than one digits (4 digits are good).  Thanks in advance!      private void promoCodeButtonActionPerformed(java.awt.event.ActionEvent evt) {                                                     Random num1 = new Random();     Random num2 = new Random();     Random num3 = new Random();      //convert Random to String so I use it with JOptionPane     String n1=num1.toString();     String n2=num2.toString();     String n3=num3.toString();      String equation = "What's the result of "+n1+"+"+n2+"*"+n3+"=?";     String given = JOptionPane.showInputDialog(null, equation,connection);      //convert String to int so I can apply equation:     int numb1 = Integer.parseInt(n1);     int numb2 = Integer.parseInt(n2);     int numb3 = Integer.parseInt(n3);     int result = numb1+numb2*numb3;     int result1 =Integer.parseInt(given);      //Random number promo code     Random promo_code = new Random();      if(given.equals(result1)){     JOptionPane.showMessageDialog(rootPane, "Correct Answer! \nHere's your promo code is:"+promo_code+"\nEnjoy! ");     }      else{     JOptionPane.showMessageDialog(rootPane, "Wrong Answer! \nTry again");      } }

How do I generate a random int value in a specific range? I have tried the following, but those do not work: Attempt 1: randomNum = minimum + (int)(Math.random() * maximum);  Bug: randomNum can be bigger than maximum. Attempt 2: Random rn = new Random(); int n = maximum - minimum + 1; int i = rn.nextInt() % n; randomNum =  minimum + i;  Bug: randomNum can be smaller than minimum.


When dissolving a polygon shapefile I get fragments in the middle (see pictures) in Qgis and R using the functions from rgeos. Has anybody an idea where this comes from and what can be done to deal with this?   original data set showing municipalities   dissolved dataset showing fragments in the middle    I would like to have only the contour of all municipalities without the fragments...

I have a set of polygons representing administrative districts.  The districts were digitized by hand, and there are small spaces (slivers) between polygons where the polygons should be touching. How can I have the polygons snap together, removing the spaces?


I'm working in $L_0$ I know I have to use the three axioms and inference rule. However, I'm finding it difficult to prove that $(\neg \alpha \rightarrow (\alpha \rightarrow \beta))$ is a theorem.  I find it very fiddly and unintuitive - as if I just have to sort of plug in random formulae and combine them to get what I need.  Any advice would be appreciated.

I am trying to prove,  $$\vdash\neg P\to (P\to Q)$$  where $P$ and $Q$ are arbitrary but otherwise fixed formulas. The only axioms and rule of inference that I can use are,  $\color{crimson}{\text{Axiom 1.}}\  P\to (Q\to P)$ $\color{crimson}{\text{Axiom 2.}}\  (S\to (P\to Q))\to((S\to P)\to (S\to Q))$ $\color{crimson}{\text{Axiom 3.}}\  (\neg Q\to\neg P)\to(P\to Q)$ $\color{crimson}{\text{Rule of Inference.}}$ .  I know that in Angelo Margaris's book First Order Mathematical Logic there is a proof (page 53) but as I have mentioned , the dot notation seems very confusing and translating them to the nested parentheses notation seems very difficult to me. So, I am trying on my own to prove the result. Can anyone help?


I want to achieve a table with the headers being rotated 90 degree so that it appears bottom up.   I use the following code with both rotation 90 and -90 but I am facing different errors. Here is the code:   \documentclass[graybox,envcountchap,sectrefs]{svmono} \usepackage{rotating} \usepackage{amssymb}% http://ctan.org/pkg/amssymb \usepackage{pifont}% http://ctan.org/pkg/pifont \usepackage{array} \newcolumntype{P}[1]{>{\centering\arraybackslash}p{#1}}  \begin{document} \begin{table} \begin{tabular}{ | P{4cm} | P{1cm} |  P{1cm} } \hline col 0 & \begin{rotate}{90} Col1 \end{rotate} & \begin{rotate}{-90} Col2 too much text is written here that i want to split on multiple line but rotated 90 degree \end{rotate}\\[25ex] \svhline first row & \checkmark & \ding{55} \\ \hline \end{tabular} \end{table} \end{document}   Here is the output:   So my questions are:   How to start from the button towards the top like first 'Col1' but to start from the bottom of the cell How to make it fit the cell size and use multi rotated line, shall I do that by hand or can it be made in an automatic manner, and if by hand how can that be done   Here is a link to the class

I'd like to create a chart where the column titles are rotated, as per this toy example:    I used the rotating package to generate the above. It has certain shortcomings: the rotate command doesn't leave space for the titles, so I have to manually space things to prevent overlaps. The turn command, by contrast, creates too much space, where each column is the width of the entire rotated column title.  There is also no easy way to have long titles be split into multiple lines.  Is there a package for creating tables of this sort, or at least one that would relieve some of the manual placing and spacing that goes into creating such a table?    This question is more to make sure I don't miss any easy way of doing what I want than seeking help on manually doing it, but the code for above is included anyways:  \begin{tabular}{r|ccc} & \begin{rotate}{60} Property 1 \end{rotate} & \begin{rotate}{60} Property 2 \end{rotate} & \begin{rotate}{60} Property 3 \end{rotate} \\ \hline System 1        &       &       &  X    \\  System 2        & X     & X     &  X    \\ System 3        & X &   &  X    \\ \hline \end{tabular}


In the following sentence, should I use "have" or "has?"      Your generous support, trust and commitment has sustained us over the years and is more important than ever in the coming year.

Can anyone tell me if I should use inspire or inspires in this phrase?     An extraordinary leader whose vision, values, integrity and boundless curiosity inspires all who follow in his footsteps.


Hi I have this following code for C#.Net  ASCIIEncoding encoding = new ASCIIEncoding(); string postData = "membershipcardnumber=" + Cardnumber; postData += ("&terminalname=" + TerminalName); postData += ("&serviceid=" + CasinoID); byte[] data = encoding.GetBytes(postData);  HttpWebRequest myRequest =   (HttpWebRequest)WebRequest.Create("http://myurl"); myRequest.Method = "POST"; myRequest.ContentType = "application/x-www-form-urlencoded"; myRequest.ContentLength = data.Length; Stream newStream = myRequest.GetRequestStream();  newStream.Write(data, 0, data.Length); HttpWebResponse response = (HttpWebResponse)myRequest.GetResponse(); // Get the stream associated with the response. Stream receiveStream = response.GetResponseStream(); // Pipes the stream to a higher level stream reader with the required encoding format.  StreamReader readStream = new StreamReader(receiveStream, Encoding.UTF8); Console.WriteLine("Response stream received."); var egm_response = readStream.ReadToEnd(); Console.WriteLine(egm_response);   the variable egm_response outputs the entire html code. This is just a part of it:

JSON Result :
     {"CreateEgmSession":{"IsStarted":0,"DateCreated":"","TransactionMessage":"Terminal already has an active session.","ErrorCode":37}}

   How can I get or parse this html and only get the value after ErrorCode?

I'm looking for a library/method to parse an html file with more html specific features than generic xml parsing libraries.


Just got a new SSD. It's a Samsung EVO 750 (120 GB). It's MBR. I have 3 operating systems in my HDD (1 TB) which is GPT (and has a loooot of partitions). One is the pre-installed Windows that came along with my laptop, I use it only for Photoshop now. The other two are Linux OSes. I am trying to create partitions in the SSD to have Ubuntu installed in one and the other have some Windows apps that need an SSD, only those apps and not the OS itself.   Ubuntu has too many settings and configs which I can't afford to lose or create again. So my best option is to clone the Ubuntu partition to one of the SSD partitions and leave the other partition as an NTFS for Windows to access.   How do I go on about it? I have checked the internet, but I seem to be lost.

I have Ubuntu 14.04 with a lot of packages and work related stuff that I am very happy with it. It is installed on my main SSD drive which is a 120GB one (I had choosen "/" when I installed ubuntu, so I beleive everything should be on this drive). It shows up as /dev/sda  Now I have added another SSD to my computer which is a 240Gb. I do not have any other storage media at hand at the moment (e.g. external hard drive).   Since the new 240GB drive has obviously more capacity and is faster (a newer generation than my 120GB one), I want to move my Linux to this new drive. This new drive shows up as /dev/sdb and at the moment it is not formatted or anything (I have literally unpackaged and inserted in my PC right now :P)  How can I safely move my linux installation to the new drive?  I can change the SATA cable so the new drive shows as /dev/sda if necessary.  This is the output of "fdisk -l" if that helps:  Disk /dev/sda: 120.0 GB, 120034123776 bytes 255 heads, 63 sectors/track, 14593 cylinders, total 234441648 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x00076d7a     Device Boot      Start         End      Blocks   Id  System /dev/sda1   *        2048   226064383   113031168   83  Linux /dev/sda2       226066430   234440703     4187137    5  Extended Partition 2 does not start on physical sector boundary. /dev/sda5       226066432   234440703     4187136   82  Linux swap / Solaris  Disk /dev/sdb: 240.1 GB, 240057409536 bytes 255 heads, 63 sectors/track, 29185 cylinders, total 468862128 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000  Disk /dev/sdb doesn't contain a valid partition table


I use viewers for open sims and grids, Like second life and osgrid, I downloaded coolviewer and opened it with wine, it loaded ok but when I try to use it  goes to "not responding"   I  have to shut it down!! What causes this? I found were you get the terminal, but do not understand its im new to this ! Is there another program I can use to open window downloads?

Can .exe and .msi files (Windows software) be installed in Ubuntu?


I want to launch a Powershell script when a usb device is unplugged. To accomplish that I would like to use a scheduled task but I don't know what event trigger I should use.  I already know that to detect when a USB device is plugged in, you have to use the following event trigger : (in Event Logs) Application and Service Logs/Microsoft/Windows/DeviceSetupManager/Admin but I am looking for the event trigger to use to detect when the device is unplugged.

I know it has been discussed that it is not possible to start an application from an usb drive upon connection due to limitations of autorun (or autoplay??) in Win 7. But it is possible to create a scheduled task having an event type trigger. Surely there must be an event occurring when the drive -- or any USB device, for that matter -- is connected.    Does anybody have the slightest idea which Event ID should I use? Or at least what type of event? Where can I find the event in event viewer?


ntoskrnl.exe!IoGetStackLimits+0x3060  when pc is idle for app 4 minutes, process starts taking app 25 % (one core) of CPU.   I have driver talent for update, I tried several windows 10 healing opetions.. but still remains. Malware scanned as well..

I have noticed that from some time my system is freezing and its probably caused by the high CPU usage which is caused by the system process.  All applications I'm running is the Skype, TeamSpeak and Chrome so it definitely shouldnt eat that amount of CPU.  You can see the problem itself and running processes in the screenshot below:    Sometimes CPU usage is reaching 90%, but the average usage is like 40-65%.  My PC parameters:   Windows 8 (customer preview) Intel Core i3 - 2350M 8 GB RAM   I'd appreciate any help attempt! Regards.  --UPDATE--  As the user below posted a great answer, I have noticed that the process that is eating the most CPU in the system is called Arthurx.sys, simple google tells that it's a TPLink driver (an wifi adapter, I have bought like 2 weeks ago!) drivers has been installed from the Windows MSDN, but also tried to install the drivers from the attached CD, but it doesn't help. From the system start, it is using like 5% of the CPU only, but after 2-4 hours of working it is growing up and reaching 40-60% of the CPU usage.  Device name: TPLink WN722N


Mobile phone technology has been growing rapidly. Nowadays, we have mobile phones with the same configuration as a Pentium-1,Pentium-2 processor + 1 GB Ram  20GB Hard disk as we had a few years ago for Desktops.  For eg: I have just ordered for Galaxy S-III, which as 1 GHz CPU, 1 GB RAM and 16 GB Permanent storage.  So, my question is : can we format (same thing as we do on a Desktop) such mobile devices and install whatever OS (Android only for now) we like ? If so, I would like to install latest Android version on my mobile. Similar to the CD-Rom drive that can hold the OS that we are going to install on our fresh Desktop, for mobile devices can't we use any USB storage drives that has the latest Android (installation source) ?

This Community Wiki question is designed to be the "canonical question" for questions asking how to upgrade one's device to a new Android version.   I want to get a newer version of the OS for my Android device. How can I do that?  See also:


Let $n\gt1$, and $h(n)$ denote the number of invertible residue classes $mod n$ that are self-inverses.   Show that $h(n)=\phi(n)$ iff $n=2,3,4,6,8,12, or 24$.

I have a hard time formulating proofs.  For this problem, I  can see that if $n$ is equal to $8,$ this statement is true.  $(\mathbb{Z}/8\mathbb{Z})^{\times}$ includes elements:  $1,3,5,7$, and all of these are roots of $1-x^2 \pmod 8.$  And obviously $8$ divides $24.$  But how do I prove this without depending on number calculations and only using theorems?  Help Please?  I need a step by step walk through of how to do this proof and what theorems would be appropriate to use.


After reading , I was wondering how the operating system 'chooses' the Metric value for a route.  I have 2 dynamically added routes for internet:        0.0.0.0          0.0.0.0      192.168.0.1    192.168.0.239     45       0.0.0.0          0.0.0.0         10.0.0.1       10.0.0.254     15   So naturally, my traffic is being routed to the gateway at 10.0.0.1 first because 15 < 45, if there are no routes on 10.0.0.1, it will be routed to 192.168.0.1 for delivery.  What I'm wondering is:  How does Windows (or any OS with a routing implementation) decide the metric value for these 2 interfaces?  I notice some people contradicting each other in the comments of the linked question when it comes to priority based on Ethernet/Wireless and the like. For this reason I want to note:   The interface with Metric 45 is a Wireless adapter The interface with Metric 15 is connected to a Hyper-V Virtual Switch hosted on the same machine.

I'm a little confused about the output I'm seeing in my routing table, particularly the 'metric' column:  $ route -n Kernel IP routing table Destination     Gateway         Genmask         Flags Metric Ref    Use Iface 0.0.0.0         192.168.0.1     0.0.0.0         UG    0      0        0 wlan0 172.16.35.0     0.0.0.0         255.255.255.0   U     0      0        0 vmnet1 192.168.0.0     0.0.0.0         255.255.255.0   U     9      0        0 wlan0 192.168.82.0    0.0.0.0         255.255.255.0   U     0      0        0 vmnet8   According to the man page, metric indicates the 'distance' to the target. I was a little confused about what exactly "target" was. I assumed it was my router (it goes to gateway 0.0.0.0, which then goes to my router at 192.168.0.1). Thus, I expected the metric to be a single hop to my router. However, it's 9! Why is this so number high?


Consider sets $A=\left\{a,\:b,\:c,\:d\right\}$ and $B=\left\{1,\:2,\:3\right\}$. How many functions can be defined with domain $A$ and codomain $B$?  How would guess it is the cardinality of the power set of $A$ x $B$, but I'm lost on this one...

In my discrete mathematics class our notes say that between set $A$ (having $6$ elements) and set $B$ (having $8$ elements), there are $8^6$ distinct functions that can be formed, in other words: $|B|^{|A|}$ distinct functions. But no explanation is offered and I can't seem to figure out why this is true. Can anyone elaborate?


I'm running an Ethereum mining rig on Xubuntu (Ubuntu 16.04.3 LTS). With this, I have been running the latest AMD Blockchain GPU drivers and ROCM kernel. I had 4 GPUs running at 29 M/H, but upon rebooting my system these dropped to 23 M/H. Initially I thought this was an issue with my AMD drivers, and tried a fresh installation of everything. However, it appears to have been caused by an update to linux image and headers to version 4.13.0-26. Running the following commands resolved the issue:  sudo apt remove linux-image-4.13.0-26-generic sudo apt remove linux-headers-4.13.0-26-generic reboot   My question: Is there a way to avoid these updating again while still being able to run other general package updates?

Because of  I'd like to prevent apt-get upgrade and Update Manager from updating the "libgtk2.0-0" package.   How can this be achieved?


I'm a teenager, so my parents are paying for my cellular plan, and have restricted my phone to be unable to use any cellular data. This means I cannot use it what so ever, I really want to play games like Pokemon GO which require the player to use cellular data? Any help?  by the way, im on an iPhone 6s+, running 9.3.3 and im jailbroken.

I downloaded Pokémon GO on my Samsung Galaxy Express and I can play it at home, but when I go outside I can't play because there is no Internet.  How can I play Pokémon GO without Internet outside?


How can I parse a string like "01-Jan-1995" to a Python datetime object?

I've got a huge list of date-times like this as strings:  Jun 1 2005  1:33PM Aug 28 1999 12:00AM   I'm going to be shoving these back into proper datetime fields in a database so I need to magic them into real datetime objects.   This is going through Django's ORM so I can't use SQL to do the conversion on insert.


Please help me to understand these complicated verbs 'to take' an 'to catch'.  I know the difference from the related topics, google e.g. "If you want to go over to Sixth Ave., you'd better take the crosstown bus. You can catch it at Broadway...."  BUT I can't see the difference between  'they caught the 12.15 train from Oxford'  'they took the 12.15 train from Oxford'  which one is more idiomatic in terms of BrE or AmE?  p.s. please do not write that it is duplicate because it's impossible to find answer to my question. They are very useful, I've read them for many times, but I can't see clearly the difference in my examples above.

Could anyone help me with finding the difference between saying "catch a bus/train/etc" and  "take a train/bus/etc"? I'm afraid I haven't been able to glean one from my dictionary.


We know that if $G$ is a finite subgroup of $\operatorname{Aut}(K)$, with $F$ the fixed field of $G$, then $G=\operatorname{Gal}(K/F)$.  Does this condition hold if $|G|=\infty$?

If $E/F$ is a field extension, and $H$ is a subgroup of $\mathrm{Aut}(E/F)$, it is quite trivial to see that $H\subset \mathrm{Aut}(E/E^H)$.   Since the theorem only shows the inclusion relationship, I think there must be a lot of examples where $\subset$ is actually $\subsetneq$. But due to lack of knowledge I can't come up with one.   Could you help me with this? Best regards.


Most StackExchange sites have picked up this new black top bar by now. One notable exception is the stackexchange.com page itself: the bar there has a different style, and no direct access to the inbox / reputation (/ hats). Furthermore, the hot questions list apparently keeps loading forever, so it doesn't seem to work properly any more. Is there some intention to replace that top bar as well soon?


So this is what I understand from General Theory of Relativity: A body freely falling towards earth's surface would be in an inertial frame of reference (air removed) with zero net force acting on it. This would cause weightlessness and would be equivalent to a body in spacetime (under no acceleration) with no gravitational masses around it (and hence no gravity). Any physical experiment in these two frames would thus give equal results making them indistinguishable. But the question is, why is the freely falling body near Earth's surface in motion in inertial frame and not at rest. Why does a ball dropped of the cliff sets in motion and not stay there suspended ? Does the geodesic formed due to spacetime curvature near earth set the ball in motion or is every body on earth having an initial velocity which is maintained once the free fall (and hence inertial frame) begins? But I also know that the body will speed up as it approaches the earth's center of gravity and hence won't remain in uniform motion. Suppose a tunnel is dug diametrically through the surface, the body would perform Simple Harmonic Motion across this tunnel speeding up and down between the tunnel ends. How is the geodesic playing a role in imparting an acceleration which we so call acceleration due to gravity in Newtonian mechanics? Could it be, since the motion of an accelerating body follows a curvature in spacetime, a curvature in spacetime is automatically imparting an acceleration to the body? I'm so confused.

They say that gravity is technically not a real force and that it's caused by objects traveling a straight path through curved space, and that space becomes curved by mass, giving the illusion of a force of gravity.  That makes perfect sense for planetary orbits, but a lot less sense for the expression of gravity that we are the most familiar with in our day-to-day lives: "what goes up must come down."  Imagine that I hold a ball in my hand, several feet off the ground, with my fingers curled around it, and my hand is above the ball.  Then I open my fingers, releasing my grip on it, being very careful to not impart any momentum to the ball from my hand as I do so.  An object at rest remains at rest unless acted upon by an outside force.  If the ball is not moving (relative to my inertial reference frame), it has no path to travel that's any different from the Earth's path through space.  It should remain at rest, hanging there in the air.  And yet it falls, demonstrating that an outside force (gravity) did indeed act upon it.  How does curved space explain this?


I need to change the permissions access based on time in Ubuntu. I have a user called "miguel" and I want miguel not to gain access on Saturdays from 00:00 to 19:00 hours.  I read in web pages that this is simple:   I write this line in /etc/pam.d/login:   account required pam_time.so  I write this line in /etc/security/time.conf:   login;*;miguel;!Sa0000-1900    I saved this files with the changes.  But this not working!! I need help!! Thanks a lot!!

Access to our computer (not only to the internet) needs to be restricted for the accounts of my kids (7, 8) until they are old enough to manage this by themselves. Until then we need to be able to define the following:   the hours of the day when computing is o.k. (e.g. 5 - 9 pm) the days of the week when computing is not o.k. (e.g. mondays to fridays) the amount of time allowed per day (e.g. 2 hours)   In 11.10 all of the following that used to do the job don't work any more:   : for > 11.10 no more available through the ppa. : command line alternative, but from 11.10 removed from the repositories. : Looks great but repeatedly crashes to force restarting X-server. So we can't use or recommed this program at the moment.   Are there any other alternatives?


I'm trying to switch off TLS 1.0 on my SQL Server 2012 server in order to comply with PCI standards.  Initially I had some trouble with the SQL Server service not starting.  I found help for this issue by following answers to a previous question:    I'm having mixed results:  I have downloaded SQL Server 2012 Cumulative Update 7 (CU 6 also works) and the SQL Server Service then starts correctly.  I had a problem not being able to sign in to the DB instance through SQL Server Enterprise Manager which was fixed by installing .Net 4.6.  Next problem, client computer running IIS Application is unable to connect to SQL instance because of a 'handshaking SSL error'. I followed advice and installed the latest SNAC native client.  This was difficult to track down and the latest version available as a download from Microsoft was from 2014. I then obtained sqlnclient.msi dated 9/7/2015 revision number {E6CB4138-3D1C-4ADC-95C4-88322B60FC14} from a sub folder generated by the extract of CU 7 - "Path to Extract Folder \1033_enu_lp\x64\setup\x64".  I've updated this version of the Native client on my IIS server (and .Net 4.6) and I'm still unable to connect remotely to the SQL instance. If I enable TLS 1.0 I'm able to connect.  The exact error I'm getting is 'A connection was sucessfully established with the server, but then an error occurred during the pre-login handshake'.  My diagnosis is I don't have the correct version of SNAC on my machine compatible with TLS 1.2 and the CU 7 as the client and server cannot handshake. However, this sqlnclient.msi was extracted from the CU 7 and I cannot find a more up to date copy.  Has anyone else experienced this problem? What version of the SNAC are you using? Where did you get it?  Thanks

The major browsers are moving beyond SSL3.0 and TLS1.0 . The PCI Security Council has declared an end-of-life date for these protocols to be considered sufficiently strong encryption.   We need to move away from these protocols, to use newer and stronger ones. On Windows servers, you can very easily disable these old protocols, and instead offer only TLS1.1 or greater.  However, as noted , Microsoft SQL Server 2008 R2 and SQL Server 2012 (Standard, at least) both will not start if those lower protocols are disabled.  However, there are a growing number of versions of MS SQL Server.  There are SQL Server Standard, Business Intelligence, Enterprise, Express, Web, and Compact editions.  And of course there is SQL Server 2008, 2012, 2014, and (in pre-release) 2016.  Which of these editions support or will support the use of only TLS1.1 or greater protocols?


Just curious about the wording for "Returning" an item by a specific date  For example:  If I ask for an item to be returned by the 25th of May, does that mean I expect the item to be returned any day before the 26th of May.  If I ask for an item to be returned before the 25th of May, does that mean I expect the item to be returned any day upto and including the 24th of May.  If I ask for an item to be returned after the 25th of May, does that mean I expect the item to be returned after and including the 26th of May.  If I ask for an item to be returned on the 25th of May, I expect this to mean that the item must only be returned on that day, no sooner or later.

We use "by" to specify time or date, as in     I have to go by 9 am.   We can also use "at" here. When to use "by" / "on" / "at"?   When "by" should be preferred over "before" or "till"?


I have a problem with partitioning my hard drive. I only have Ubuntu installed but I cannot partition with g-parted while being on Ubuntu. I want to decrease the size of my partition to make space for installing Linux Mint. What do i do? I already have one partition called /dev/sda1 but I'm unable to make it smaller. I already deleted my swap partitions.

Previously, I have installed Windows 7 on my 320 GB laptop with three partitions 173, 84 and 63 GB each. The 63 GB partition was where the Windows was installed. The rest were for file containers.  Now I changed my OS to Ubuntu 12.04 LTS. I installed Ubuntu by replacing the entire Windows 7 on the 63 GB partition. The rest of the partitions remain as an NTFS Windows partition and I can still access them both (the 173 and 84 GB partitions).  Now I want to change the two partitions of Windows into an Ubuntu format partitions plus most importantly, I want to extend the 63 GB partition to more than a 100 GB because at the moment I am running out of disk space. Whenever I try to install any application, especially using wine, it always complains for a shortage of disk space.  How do I do the extending activity before I entirely format my laptop again and lose all the important files on my partitions?


I try to develop some code that loops through a set of geometries (ordered by id)  and deletes from the next neighboring geometry based on the size, but  my syntax seems at the loop seems to be incorrect.  When I run:  WITH firstblocks AS(  SELECT  ST_Buffer(ST_Line_Substring(the_geom, 8*n/length,   CASE     WHEN 8*(n+1) < length THEN 8*(n+1)/length     ELSE 1   END),4, 'endcap=flat join=mitre mitre_limit=3.0' ) As the_geom  FROM   (SELECT    ST_LineMerge(geom) AS the_geom,   ST_Length(geom) As length   FROM example_route_single_feature   ) AS t  CROSS JOIN generate_series(0,CEIL(length/8)::int) AS n WHERE n*8/length < 1  )  SELECT the_geom FROM firstblocks;  DO $do$ BEGIN     FOR i IN the_geom LOOP         IF ST_Area(i) <= ST_Area(lead(i))          THEN             ST_Difference(i, lead(i)) ;         ELSE              ST_Difference(lead(i), i) ;         END IF;     END LOOP; END      $do$   I get the error:  SQL error: WITH firstblocks AS(  SELECT  ST_Buffer(ST_Line_Substring(the_geom, 8*n/length,   CASE   WHEN 8*(n+1) < length THEN 8*(n+1)/length   ELSE 1   END),4, 'endcap=flat join=mitre mitre_limit=3.0' ) As the_geom    FROM   (SELECT    ST_LineMerge(geom) AS the_geom,   ST_Length(geom) As length   FROM example_route_single_feature   ) AS t    CROSS JOIN generate_series(0,CEIL(length/8)::int) AS n WHERE n*8/length < 1  )  SELECT the_geom FROM firstblocks;  DO $do$ BEGIN   FOR i IN the_geom LOOP      IF ST_Area(i) <= ST_Area(lead(i))       THEN            ST_Difference(i, lead(i)) ;         ELSE            ST_Difference(lead(i), i) ;         END IF;     END LOOP; END        $do$ returned 0 [ERROR:  syntax error at or near "the_geom" LINE 26:   FOR i IN the_geom LOOP                     ^ ]   I'm a PostGIS beginner and not so fit with the PostgrSQL-Syntax, so I would be very happy if someone can point whats wrong with the code.  I'm using PostGIS 2.5.1

I try to remove the artifacts which occur when running the ST_Buffer function in PostGIS PostGIS 2.5.1 (See picture). For this case I wrote a function that should loop trough every segment (row) and erase (ST_Difference) the Polygons with the smaller areas (I assume the "normal-shaped") from the bigger ones (With additional artifacts).   --CREATE TABLE line(name char(10), geom geometry); --INSERT INTO line VALUES('line','LINESTRING(0 0,30 10,40 30,70 40)');  WITH firstblocks AS(  SELECT  row_number() Over() AS id, ST_Buffer(ST_Line_Substring(the_geom, 8*n/length,   CASE     WHEN 8*(n+1) < length THEN 8*(n+1)/length     ELSE 1   END),4, 'endcap=flat join=mitre mitre_limit=3.0' ) As the_geom  FROM   (SELECT    ST_LineMerge(geom) AS the_geom,   ST_Length(geom) As length   FROM line   ) AS t  CROSS JOIN generate_series(0,CEIL(length/8)::int) AS n WHERE n*8/length < 1  )  --Erase the smaller geometry from the bigger one SELECT      CASE          WHEN ST_Area(the_geom) <= ST_Area(lead(the_geom) OVER(PARTITION BY id ORDER BY id))         THEN ST_Difference(the_geom, lead(the_geom) OVER(PARTITION BY id ORDER BY id))         ELSE ST_Difference(lead(the_geom) OVER(PARTITION BY id ORDER BY id), the_geom)     END AS new_geom FROM firstblocks;   The code works but loading the data as a new layer in the QGIS-Database Manager throws out the error: There was an error creating the SQL layer ... Somehow I am struggling with the conditional statements, while using a moving window approach. How can I combine them successfully?


A is a square matrix $n \times n$. Prove that $$A^n=0 \Leftrightarrow tr(A^k)=0, \, k=0,1,2,...,n $$

Let $A$ be an $n\times n$ complex nilpotent matrix. Then we know that because all eigenvalues of $A$ must be $0$, it follows that $\text{tr}(A^n)=0$ for all positive integers $n$.  What I would like to show is the converse, that is,      if $\text{tr}(A^n)=0$ for all positive integers $n$, then $A$ is nilpotent.   I tried to show that $0$ must be an eigenvalue of $A$, then try to show that all other eigenvalues must be equal to 0. However, I am stuck at the point where I need to show that $\det(A)=0$.  May I know of the approach to show that $A$ is nilpotent?


I have a wpf app in which one of the functions is to copy files. It functions correctly but can sometimes freeze the UI, so I am trying to add async/await functions to it. this is the code: if (dialog.ShowDialog() == System.Windows.Forms.DialogResult.OK)         {             string[] files = filePickedTextBox.Text.Split('\n');             await Task.Run(() =>                 {                     foreach (var file in files)                     {                         try                         {                             AddValueLoadingBar(20, true);                             File.Copy(file, Path.Combine(dialog.SelectedPath, Path.GetFileName(file)));                             newDirTextBox.Text = Path.Combine(dialog.SelectedPath, Path.GetFileName(file));                         }                          catch(Exception ex)                         {                             newDirTextBox.Text = ex.ToString();                         }                          finally                         {                             AddValueLoadingBar(100, true);                         }                     }                                     });  I have tried adding dispatcher.invoke in several locations but always get an error that it's asking for a request from a different thread, when it needs to talk to the textbox. I've been at this for hours and have searched many stackoverflow threads and other documents online but I cant figure out how to implement this. Also I know my progress bar implementation sucks..but I'm not worried about that at the moment since I cant get this to run without freezing in the first place. Any help would be great. Thx

I have a scenario. (Windows Forms, C#, .NET)   There is a main form which hosts some user control. The user control does some heavy data operation, such that if I directly call the UserControl_Load method the UI become nonresponsive for the duration for load method execution. To overcome this I load data on different thread (trying to change existing code as little as I can)   I used a background worker thread which will be loading the data and when done will notify the application that it has done its work.   Now came a real problem. All the UI (main form and its child usercontrols) was created on the primary main thread. In the LOAD method of the usercontrol I'm fetching data based on the values of some control (like textbox) on userControl.    The pseudocode would look like this:  CODE 1  UserContrl1_LoadDataMethod() {     if (textbox1.text == "MyName") // This gives exception     {         //Load data corresponding to "MyName".         //Populate a globale variable List<string> which will be binded to grid at some later stage.     } }   The Exception it gave was     Cross-thread operation not valid: Control accessed from a thread other than the thread it was created on.   To know more about this I did some googling and a suggestion came up like using the following code  CODE 2  UserContrl1_LoadDataMethod() {     if (InvokeRequired) // Line #1     {         this.Invoke(new MethodInvoker(UserContrl1_LoadDataMethod));         return;     }      if (textbox1.text == "MyName") // Now it wont give an exception     {     //Load data correspondin to "MyName"         //Populate a globale variable List<string> which will be binded to grid at some later stage     } }   BUT BUT BUT... it seems I'm back to square one. The Application again  become nonresponsive. It seems to be due to the execution of line #1 if condition. The loading task is again done by the parent thread and not the third that I spawned.  I don't know whether I perceived this right or wrong. I'm new to threading.  How do I resolve this and also what is the effect of execution of Line#1 if block?  The situation is this: I want to load data into a global variable based on the value of a control. I don't want to change the value of a control from the child thread. I'm not going to do it ever from a child thread.   So only accessing the value so that the corresponding data can be fetched from the database.


I am posting the Latex main file MWE herewith. While trying to compile file, getting an error as described below in line--.\maketitle. Can anyone please help me resolve it? Working on texmaker + texlive.  \documentclass{SVNITPhDrpsPB} %\documentclass[newchapterodd]{SVNITPhDrpsPB} % Uncomment to start every new chapter on odd page. Do not forget to comment previous line 20.  % Necessary packages (Do not comment these) \usepackage{fancyhdr} \usepackage{longtable} \usepackage{array} \usepackage{graphicx}  %Preamble  %Do not omit the following fields \rpsNumber{} %RPS number \thesisType{Credit Seminar} %Type (Ex. Thesis) \atitle{Mr.} %Author title. Valid entries : Mr. Ms. Mrs. \author{Saurabh Kumar Pandey} %Author name \title{Collaborative Data Processing in Wireless Sensor Networks} %Report title \dept{Computer Engineering} %Department name \regno{DS14CO006} %Registration number  \semester{Odd} %Even or odd \stitleI{Dr.} %Supervisor title. Examples : Dr., Prof. \supervisorI{xxx} %Supervisor name \supervisorA{xxx} %Supervisor's affiliation / Institution \addressInstN{xxx} %Institute name line1 \addressInstI{xxx} %Institute name's initials \addressInstD{xxx} %Institute name line2 \addressInstP{xxx} %Institute name line3 (Place) \acMonth{May} %Month \acYear{2014 -- 2015} %Academic Year \calYear{2015} %Calander Year \instlogo{./fig/SVNITlogo.pdf} %Institute logo file path  % User packages (You can add as many as you want) \usepackage{amssymb}  %  for double struck characters \usepackage{subfigure} % for subfigures  \usepackage{amsmath}  % User commands \newcolumntype{L}[1]{>{\raggedright\let\newline\\\arraybackslash\hspace{0pt}}m{#1}} \newcolumntype{C}[1]{>{\centering\let\newline\\\arraybackslash\hspace{0pt}}m{#1}} \newcolumntype{R}[1]{>{\raggedleft\let\newline\\\arraybackslash\hspace{0pt}}m{#1}}  \newcommand{\BigO}[1]{\ensuremath{\operatorname{O}\bigl(#1\bigr)}}   %\usepackage{enumitem} \begin{document}  \addpageborder  %%Create the title page \maketitle  \pagenumbering{roman} \setcounter{page}{2}  %Create the Table1 (Admin) page \putTableAdmin{\input{./Tables/tableAdminData}}  %Create the Table2 (Technical) page \putTableTech{\input{./Tables/tableTechData}}  % Create the decleration page \putdecleration  % Create the approval page \putapproval  % Create the acknowledgement page \putsvnitack{ \input{./Chapters/Ack} }  % List of publications %\input{./Chapters/Publication}  % Create the abstract page \putsvnitabstract{ \input{./Chapters/Abstract} }  % Table of contents \tableofcontents\newpage  % List of figures \addcontentsline{toc}{section}{List of Figures} % Entery in ToC \listoffigures\newpage  % List of tables \addcontentsline{toc}{section}{List of Tables} % Entry in ToC \listoftables\newpage  \clearpageborder  % To change page number and style at any time, use the following %\pagenumbering{roman} %\setcounter{page}{13} \pagenumbering{arabic} \setcounter{page}{1}  % Your RPS chapters  %%Chapter 1 \input{./Chapters/Introduction} \input{./Chapters/Review} \input{./Chapters/QoS} \input{./Chapters/Routing} \input{./Chapters/Summary}  % Bibliography \bibliographystyle{IEEEtran} \bibliography{Literature} \nocite{*}   \end{document}   Error:  ! Undefined control sequence. <recently read> \c@lor@to@ps l.72 \maketitle The control sequence at the end of the top line of your error message was never \def'ed. If you have misspelled it (e.g., `\hobx'), type `I' and the correct spelling (e.g., `I\hbox'). Otherwise just continue, and I'll forget about whatever was undefined.


I have a list of equations that I want to enumerate using itemize.  The equations should also be numbered equations.  This is no problem if those equations fit onto one line -- I just typeset them between dollar signs (and use the macro from the first answer to  to number things).  The problem arises when some of the equations take multiple lines.  I want to use \begin{split} to split them up.  The problem is that using \begin{equation} and \begin{split} forces everything to be on a new line, and I want this stuff to appear on the line with the big dot from itemize.  It won't let me use split in in-line math.  How can I get this to work?  EDIT : Here is an example to illustrate what I want:  \documentclass{article} \usepackage{amsmath} \begin{document}  \begin{itemize} \item \[\begin{split} 7x+2y = &3z+7w\\         &+23654 \end{split}\] \end{itemize}  \end{document}   The problem with the above is two-fold : first, the math is on a separate line from the big dot, and second it is centered.  I ignored the numbering at this point to make things easier to understand.

I'm writing a math paper in LaTeX and for math formulas I'm just using $$math formula$$. Is is possible to numerate formulas? Or do I have to you use some specific commands such as align?


One of the main reasons for not using OTP in everydays life is that it is highly  - for encrypting 4GB of files we need a 4GB key that needs to be exchanged secure.  I've had an idea on how to get past this problem and want the opinions of experts (thats you!) about it. The main goal is to maintain the advantages of a OTP: .  The main idea is to use a stretched hashing algorithm for deriving the OTP from a given password. This stretched hash iterates and adds the hash of the previous data to its content to create a new hash for the next data chunk making it .  This is my designed implementation in pseudo code.  Method createOTP ( CLEARDATA, PASSWORD, ALGORITHM )     set OTP to empty     set LASTSALT to derivation of given parameters     While length of OTP smaller than length of CLEARDATA         set LASTSALT to stretched hash of PASSWORD and LASTSALT using ALGORITHM         set OTP to OTP and LASTSALT     End While     set OTP to OTP with length of CLEARDATA     Return OTP End Method   I do understand that the amount of possibilities is drastically reduced by using a hash algorithm. It should be impossible to verify that a given password is correct though as all passwords create an OTP with a different outcome producing possible legit words. The amount of computing power is also an advantage as the creation of such a big key can take a lot of time and is memory expensive.

I am very new to cryptography (so be kind), but I have a question that may seem silly.   If the one-time pad is the perfect cipher and impossible to crack, why would the following algorithm not be one of the strongest:  To encrypt:   generate a random bit array using a pseudo number generator with the key as the seed  The generated bit array is the size of the data use a simple XOR to encrypt using the generated bit array   To decrypt:   pseudo-random number generator will generate the same bit array with the same seed (the key) generate bit array the same size of the encrypted data run XOR on encrypted data using bit array that's generated   This is very simplified, but you can imagine how for larger encryption you could break down the data into blocks, and in order to ensure that the block bit arrays are random a new seed for each can be derived from the key. So, if $f(k)$ is the pseudo random number generator, and b is the block number, you can encrypt each block with $f(k+b)$. ($k$ is key)   Instead of using a pseudo-random number generator, you could use some hash algorithm to generate the pad.    (assuming you can use equivalently strong keys) would this not be a very strong cipher method? Perhaps it may be strong and heavy on memory since the pad needs to be the size of the data. So during encryption and decryption you need to generate a pad that's equivalent to the size of the data.   Is there a flaw in this algorithm, or would something like this not be practical and much slower than current standards?


Is it the same in Python ?  import time.sleep   and   from time import sleep   Can anyone describe what is the difference between those.

I'm writing a Python application that takes as a command as an argument, for example:  $ python myapp.py command1   I want the application to be extensible, that is, to be able to add new modules that implement new commands without having to change the main application source. The tree looks something like:  myapp/     __init__.py     commands/         __init__.py         command1.py         command2.py     foo.py     bar.py   So I want the application to find the available command modules at runtime and execute the appropriate one.  Python defines an __import__ function, which takes a string for a module name:     __import__(name, globals=None, locals=None, fromlist=(), level=0)      The function imports the module name, potentially using the given globals and locals to determine how to interpret the name in a package context. The fromlist gives the names of objects or submodules that should be imported from the module given by name.       Source:    So currently I have something like:  command = sys.argv[1] try:     command_module = __import__("myapp.commands.%s" % command, fromlist=["myapp.commands"]) except ImportError:     # Display error message  command_module.run()   This works just fine, I'm just wondering if there is possibly a more idiomatic way to accomplish what we are doing with this code.  Note that I specifically don't want to get in to using eggs or extension points. This is not an open-source project and I don't expect there to be "plugins". The point is to simplify the main application code and remove the need to modify it each time a new command module is added.


Trying to compile the seemingly straightforward code  \documentclass{standalone} \usepackage{booktabs} \usepackage{array} \usepackage{xparse} \usepackage{tabu}  \NewDocumentCommand{\TblHdr}{O{1} m}{   \multicolumn{#1}{c}{\bfseries #2} }  \begin{document} \begin{tabu}{r*{4}{c}} \toprule \TblHdr{1} & \TblHdr{2} & \TblHdr{3} & \TblHdr{4} \\ \midrule 1 & 2 & 3 & 4 \\ A & B & C & D \\ W & X & Y & Z \\ \bottomrule \end{tabu} \end{document}   gives me the following error:  ! Misplaced \omit. \multispan ->\omit                     \@multispan  l.20 \end{tabu}  ?   I have searched the site, but none of the other questions/answers appeared to have helped. Furthermore, if at all possible, I'd like to understand what exactly is going on here. As I said, the code seems pretty straightforward.

The following example has two normal LaTeX \newcommand macros and two xparse \NewDocumentCommand for specifying multicolumn text. The only difference between each pair of commands is one has the alignment character as part of the macro and one does not.  However, the xparse version that requires the alignment character to be outside of the macro does NOT work and results in Misplaced \omit. error.  \documentclass{article} \usepackage{xparse}  \newcommand{\MulticolumnA}[3]{&\multicolumn{#1}{#2}{#3}} \newcommand{\MulticolumnB}[3]{ \multicolumn{#1}{#2}{#3}}  \NewDocumentCommand{\MulticolumnX}{m m m}{&\multicolumn{#1}{#2}{#3}} \NewDocumentCommand{\MulticolumnY}{m m m}{ \multicolumn{#1}{#2}{#3}}  \begin{document} \[ \begin{tabular}{lllllll}     {a} \MulticolumnA{4}{l}{A-abcdefghijkli}\\     {a}&\MulticolumnB{4}{l}{B-abcdefghijkli}\\     {a} \MulticolumnX{4}{l}{X-abcdefghijkli}\\     %{a}&\MulticolumnY{4}{l}{Y-abcdefghijkli}\\     {col1}&col2&{col3}&{col4}&{col5}\\ \end{tabular} \] \end{document}   Above compiles as is, but does not compile if the one line is uncommented.


What I have so far does pretty much nothing    def dress_me(shirt, tie, suit):    #    if type(shirt) != list or type(tie) != list or type(suit) != list:     #        return None             combinations = dress_me(shirt, tie, suit)             for combo in combinations:                 print(combo)

I have a list with 15 numbers in, and I need to write some code that produces all 32,768 combinations of those numbers.   I've found  (by Googling) that apparently does what I'm looking for, but I found the code fairly opaque and am wary of using it. Plus I have a feeling there must be a more elegant solution.  The only thing that occurs to me would be to just loop through the decimal integers 1–32768 and convert those to binary, and use the binary representation as a filter to pick out the appropriate numbers.   Does anyone know of a better way? Using map(), maybe?