How to install Android-studio? with ppa from official page

I tried to install Android studio but I think I got it: wrong wget link or something.   wget https://dl.google.com/dl/android/studio/ide-zips/1.5.1.0/android- studio-ide-141.2456560-linux.zip -p /opt/ apt-get install unzip unzip android-studio-ide-141.2456560-linux.zip -d /opt /opt/android-studio/bin/studio.sh -y ./studio.sh


How to prove $\operatorname{Tr}(AB) = \operatorname{Tr}(BA)$?

there is a similar thread here , but I'm only looking for a simple linear algebra proof.


Prove or Disprove: If every nontrivial subgroup of a group $G$ is cyclic, then $G$ is cyclic.    This is a question from page $181$, Chapter $3.4$ Elements of Modern Algebra ($8^{th}$ Edition) by Linda Gilbert.  My intuition tells me that the given statement is false, however, I cannot seem to find a rigorous argument (or counterexample) to disprove the statement. Can anyone please point me in the right direction?  I know that if a group $G$ is cyclic, then every subgroup is cyclic. This is not an if and only if statement - hence my intuition telling me the above mentioned statement is false.


I'd like to embed an online map inside of a Word document for my geography task in school. I have the code for an iframe of a map at www.arcgis.com.  How do I insert it in the document? I'm using Word 2013.


Which is the Best way to prvent SQL injection using PHP

Now my query, SP  is breaking if i enter         ssds ' " '  sdsds   or  just       ' " '   this is for mainly search functionality.  Which will be the best way to avoid all possibilities.  eg: str_replace  or better ways.. write some function!


I need to get the number of rows of a query (so I can paginate results).  As I'm learning codeigniter (and OO php) I wanted to try and chain a ->num_rows() to the query, but it doesn't work:  //this works: $data['count'] = count($this->events->findEvents($data['date'], $data['keyword']));  //the following doesn't work and generates // Fatal Error: Call to a member function num_rows() on a non-object $data['count2'] = $this->events->findEvents($data['date'], $data['keyword'])->num_rows();   the model returns an array of objects, and I think this is the reason why I can't use a method on it.   function findEvents($date, $keyword, $limit = NULL, $offset = NULL) {     $data = array();      $this->db->select('events.*, venues.*, events.venue AS venue_id');     $this->db->join('venues', 'events.venue = venues.id');      if ($date)     {         $this->db->where('date', $date);     }      if ($keyword)     {         $this->db->like('events.description', $keyword);         $this->db->or_like('venues.description', $keyword);         $this->db->or_like('band', $keyword);         $this->db->or_like('venues.venue', $keyword);         $this->db->or_like('genre', $keyword);     }      $this->db->order_by('date', 'DESC');     $this->db->order_by('events.priority', 'DESC');      $this->db->limit($limit, $offset); //for pagination purposes     $Q = $this->db->get('events');     if ($Q->num_rows() > 0)     {         foreach ($Q->result() as $row)         {             $data[] = $row;         }     }      $Q->free_result();     return $data; }      Is there anything that i can do to be able to use it? EG, instead of $data[] = $row; I should use another (OO) syntax?


How to precisely measure low currents if the voltage is high? Shoestring Budget

I have a circuit that will be using an ignition coil from a car to produce voltages in the range of 20kV to 30kV.  These will be arced across a gap and I'd like to measure the current across the spark gap.  Can I use a normal multimeter for this if the current is low? If not is there a cheap (<£15 including p&p) way to measure this current non-destructively?  PS I am in the UK at college and we need to keep our project under budget, and this is already proving difficult but we are very interested in the results of the experiment so we would rather not have to do something else.


I wanted to know how I could configure multi-touch gestures in Ubuntu. In windows I can do this using the synaptics driver software.  I have already used synclient to configure the taps, palmdetect, scroll, etc. But I'd also want gesture support. Is is even possible?  System-Info: Ubuntu 12.10, Synaptics clickpad


I am trying to find the last 4 digits of $2^{2016}$. Here is where I am up to: 2^2016 = x mod 10000 2^2016 = x mod 625 - I used Eulers function to find that 2^16 = 1 mod 625 = 536 2^2016 = x mod 16 Now I am stuck. The second equation can not use Euler so how do I continue? Thanks


Why couldn't Harry see Thestrals at the end of Goblet of Fire?

Why couldn't Harry see Thestrals at the end of Goblet of Fire after the senseless and shocking death of Cedric Diggory?   At the end of Goblet of Fire, the carriages still appeared horseless to Harry:     Hermione turned away, smiling at the horseless carriages which were now trundling towards them up the drive, as Krum, looking surprised, but gratified, signed a fragment of   parchment for Ron.   Goblet of Fire - Page 629 - British Hardcover - Adult Edition   At the beginning of Order of the Phoenix, Harry sees the Thestrals for the first time:     Here stood the hundred or so horseless stagecoaches that always took the students above first year up to the castle. Harry glanced quickly at them, turned away to keep a lookout for Ron and Hermione, then did a double-take.   The coaches were no longer horseless. There were creatures standing between the carriage shafts.   Order of the Phoenix - Page 178 - British Hardcover - Adult Edition   We know that only those who have seen death can see Thestrals:     ‘Don’ worry, it won’ hurt yeh,’ said Hagrid patiently. ‘Righ’, now, who can tell me why some o’ yeh can see ’em an’ some can’t?’   Hermione raised her hand.   ‘Go on then,’ said Hagrid, beaming at her.   ‘The only people who can see Thestrals,’ she said, ‘are people who have seen death.’   ‘Tha’s exactly right,’ said Hagrid solemnly [...]   Order of the Phoenix - Page 394 - British Hardcover - Adult Edition   A month went by between Cedric's death and the end of the spring term -- is this enough time for Harry to have truly internalized Cedric's death? Goblet of Fire indicates that Harry was in shock following Cedric's murder, but was able to relate the story of Cedric's death to Mr. and Mrs. Diggory.     When he looked back, even a month later, Harry found he had few memories of the following days. It was as though he had been through too much to take in any more. The recollections he did have were very painful. The worst, perhaps, was the meeting with the Diggorys that took place the following morning.   [...]   ‘He suffered very little, then,’ she said, when Harry had told her how Cedric had died.'   Goblet of Fire - Page 621 - British Hardcover - Adult Edition   So, then, why couldn't Harry see Thestrals at the end of Goblet of Fire?


How do I keep the original material colour of a mesh after projection painting?

I've been trying to apply decals onto a certain mesh of my gun using projection painting which works well, however I'm projecting an image with a transparent background yet the empty space (i.e. not covered by the image) is just coloured black, not the mesh's original material colour (the dark grey on the top bit of the gun). This gun is being exported into roblox studio, so the black in blender doesn't even match the black of roblox studio which is another reason why I need to fix this (look at mesh to its right for colour reference). I'm really new to projection painting, so I'm hoping I could find some answers here. Does anyone know how to recover this original colour?


gnome-screenshot area clipboard not working on Ubuntu 17.10

I have a fresh install of Ubuntu 17.10.1. Being used to the Ctrl-Shift-PrtScr, I really miss that. For some reason, it just doesn't copy the screenshot to clipboard.  When I manually execute gnome-screenshot --area --clipboard, the same thing happens. It gives me a crosshair to select an area, makes a shutter sound and the newly made screenshot is nowhere to be seen. Not even in the Pictures folder.  What's the issue here?


How was it proven that a quantum entanglement measurement of particle A, affects properties of particle B

If I understood the wikipedia article correctly, quantum entanglement claims that information travels instantly between entangled particles. An act of measurement on one of the entangled particles changes (I think just determines) properties of other particle.   How was it proven that the properties are not just predetermined?  For example, if I have 2 particles and know its charge is zero, then if I measure one particle and its charge is positive, I know that the other particle is negative cause of law (equation), their charge was always such, even before my measurement, it was predetermined. Or math equation $x+2=4$, I know the outcome, I know operation, I know one operand, I can solve it and find $x$. I can determine $x$ but I don't change it. Can multiple particles be entangled? What happens then?  Does the measurement of one particle effect other particles all together? If we make a math analogy with $x+y-2=0$, we measure $x$ and it is $1$, we know $y$ is $1$, but what if the equation is complex and there are multiple possible answers? Can we say that in an atom, the nucleus and electrons is quantum entanglement?  Suppose electrons around atom nucleus not particles but just a function, and they are not determined until we measure the nucleus. For example we found +6 protons in the nucleus, now using math equation $x+6=0$, we know that there must be 6 electrons. Then we measure one electron position, and again we can determine other electron positions using some math equations. How it is different from quantum entanglement? Why we say that in this scenario everything is predetermine and we only discover it, and in another scenario some "spooky action" takes place? How is it different from "wavefunction collapse" (measurement problem) and the "which way" double split experiment?  To me it looks like very close things.


Where did about:blank get its name from?

All browsers I tested support about:blank as a URL for an empty page. I understand the blank, but where comes the about from?


Three particles $A,$ $B$ and $C$ are situated at the vertices of an equilateral $ΔABC$ with sides each of length $l.$   Particle $A$ moves towards particle $B$ with a speed of $s.$ Simultaneously, particle $B$ moves with the same speed towards particle $C$ and $C$ moves towards particle $A.$ Tracing out a pursuit curve, they meet each other.  What is the distance covered by particle $A$ when it revolves around by $2π$ radians?  I could find out the total time taken by the particle $A$ to collide with $B$ (which is $\frac{2l}{3s}$) and total distance $l$ covered by $A$ but I could not figure out the distance traced to revolove 360°.


Should the title be included in the question?

In  The question acts as if the title is the first sentence by continuing with "I am referring specifically to the MCU version"  Often, i open up a number of questions i want to read and then skip the title when reading them. This almost always works, but for questions like the above, i need to re-read the title.  This leads me to wonder:   Should the title be included in the question (in some form) or can the question be treated as continuing from the title. If the title is a summary, would it be better if the Title field were under the question (above tags), so the user summarized what has already ben asked rather than what he expects to ask?


Payeezy credit card payment integration using HMAC

I was recently working on Payeezy ()  integration with sales force. Payeezy was using HMAC to generate authorization header with help of certain apiKey, Token, TimStamp, Nonce and API Secret key. if you follow the link you will have sample request available in there online developer doc.  Challenged i was facing in apex class while generating using "Crypto.generateMac" which never matched compared to developer site even after using same data.  But using "crypto-js.js" library in apex page i am able to generate the same authorization header.  Here is the sample code  <apex:page applyHtmlTag="false" sidebar="false" applyBodyTag="false" cache="false" standardStylesheets="false" showHeader="false"        controller="payeezeController" >  <head>     <script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.9-1/crypto-js.js"></script>     <script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.9-1/hmac-sha256.js"></script>     <script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.9-1/enc-hex.js"></script> </head>  <body>      <script>         var apiKey = 'o************************89P';         var nonce = '3*****************0';         var timestamp = '1575278390754';         var token = 'f*******************************t';         var data = apiKey + nonce + timestamp + token + '{"transaction_type":"authorize","method":"credit_card","amount":"1299","currency_code":"USD","credit_card":{"type":"visa","cardholder_name":"John Smith","card_number":"4788250000028291","exp_date":"1020","cvv":"123"}}';         var privateKey = '5*******************************************';          var signatureBlob = CryptoJS.HmacSHA256(data, privateKey);         var sign = btoa(CryptoJS.enc.Hex.stringify(signatureBlob));          console.log('sign : ' + sign);                               </script>  </body>     My requirement was we need to capture amount first & generate transaction id store in the sales-force and we need to deduct once whole application has submitted successfully.  Deduction of the amount i need to be done from apex class only. I didn't find any article or answer online which will help me generate equivalent HMAC which used to generate from above code.


A mesh "jumps" forward after parenting to an armature

When I parent mesh to an armature (automatic weights), the mesh "jumps" forward a bit. If I select armature and switch to edit mode it "jumps" backward a bit.   Why is it happening and how can I fix it? I already applied location, rotation, and scale to the mesh and armature, but it didn't help.  Thank you in advance!


How to fly with Ryanair as a non-EU citizen?

I received my Schengen visa, thanks to numerous Q&A found on this site. I have flights booked for in and out, and I'm considering to use Ryan Air to travel between a few cities.   I'm a Sri Lankan citizen with a passport that is not due to expire anytime soon. I have an ETAS SCHENGEN visa on my passport.   In the Ryan Air web site,  says that non EU/EEU passengers should get their documents stamped by a special counter.    Is it legal for a third party in general to stamp my passport? I understand immigrant officers can stamp it, and may be banks too when exchanging currency. But can a third party airline?    I should probably ask this from Ryan Air, but given their lack of support (as far as I can see), I thought to ask this on the people I love for traveling. That is you!   Is this a one-time document check only, or do I have to go through the same procedure every time? Does this mean I cannot check-in online, and have to pay for their desk check-in every time, even if I wanted to do so online?


Lets say we have a delegate  public delegate void MyEventHandler(string x);   and an event handler  public event MyEventHandler Something;   we add multiple events..  for(int x = 0; x <10; x++)   {    this.Something += HandleSomething; }   My question is .. how would one remove all methods from the eventhandler presuming one doesn't know its been added 10 (or more or less) times?


How do I integrate the Poisson equation to determine the electric potential along a particular direction (e.g., $z$)?

This question is a sequel of sorts to my  about .  In the paper, the authors performed molecular dynamics (MD) simulations of parallel-plate supercapacitors, in which liquid resides between the parallel-plate electrodes.  The system has a "slab" geometry, so the authors are only interested in variations of the liquid structure along the $z$ direction.  In my previous question, I asked about how particle number density is computed.  In this question, I would like to ask about how the electric potential is computed, given the charge density distribution.  Recall that in CGS (Gaussian) units, the Poisson equation is   $$\nabla^2 \Phi = -4\pi \rho$$  where $\Phi$ is the electric potential and $\rho$ is the charge density.  So the charge density $\rho$ is proportional to the Laplacian of the potential.  Now suppose I want to find the potential $\Phi(z)$ along $z$, by integrating the Poisson equation.  How can I do this?  In the paper, on page 254, the authors write down the average charge density $\bar{\rho}_{\alpha}(z)$ at $z$:  $$\bar{\rho}_{\alpha}(z) = A_0^{-1} \int_{-x_0}^{x_0} \int_{-y_0}^{y_0} dx^{\prime} \; dy^{\prime} \; \rho_{\alpha}(x^{\prime}, y^{\prime}, z)$$  where $\rho_{\alpha}(x, y, z)$ is the local charge density arising from the atomic charge distribution of ionic species $\alpha$, $\bar{\rho}_{\alpha}(z)$ is the average charge density at $z$ obtained by averaging $\rho_{\alpha}(x, y, z)$ over $x$ and $y$, and $\sum_{\alpha}$ denotes sum over ionic species.  The authors then integrate the Poisson equation to obtain $\Phi(z)$:  $$\Phi(z) = -4\pi \sum_{\alpha} \int_{-z_0}^z (z - z^{\prime}) \bar{\rho}_{\alpha}(z^{\prime}) \; dz^{\prime} \; \; \; \; \textbf{(eq. 2)}$$  My question is, how do I "integrate the Poisson equation" to obtain equation (2)?  How do I go from  $\nabla^2 \Phi = -4\pi \rho$ to equation (2)?  In paricular, where does the $(z - z^{\prime})$ factor come from?   Thanks for your time.


Is any built-in tool in Lubuntu (or other Linux from Ubuntu family) allows restore operating system to brand-new snapshot with all default settings?


Is there a dancing pony on the screen? (Visual testing)

Motivated by .  We currently have a rather rich subset of end-to-end tests for our AngularJS applications. And, we do get a lot of visual/layout/design issues on every single development iteration. Usually, we do not cover this kind of issues with end-to-end tests and testing the fixes manually. The reasoning was always - too hard, too fragile, too expensive to automate.  In some cases though, a style of an element or block on a page is really critical for an end-user and it would make sense to have an automated end-to-end test checking it. We try to check the colors, font styles and other CSS properties inside our Protractor tests, but it is still checking only these specific things and not an element or part of a page as a whole. Plus, the assertions themselves are not readable and easy to break, for example:  expect(somePage.someElement.getCssValue("background-color")).toEqual("rgba(255, 211, 205, 1)");     We are thinking of adding some sort of a visual component to our tests. Ideally, comparing screenshots of what we expect an element to look like and how it actually looks. But, there are a lot of open questions at this point:   how reliable can it be - would it depend on the browser, resolution and other parameters of the test machine setup? is it possible to integrate with our existing Protractor test codebase or we need a separate specialized tool for that? test result reporting - how would we present the test results?   Have you done something similar and how did you address the above mentioned issues? Was it worth the cost of maintenance?


Generalized Euclid's Lemma:   Let $a_1,a_2,a_3,...,a_n \in \mathbb{Z}$.  If $p$ is a prime number such that $p | a_1 \cdot a_2 \cdot a_3 \cdot ... \cdot a_n$,  then $\exists i \in \{1,2,3,...,n\}$ such that $p|a_i$.  According to my book, it says the proof can be done by using induction.  How would I go about writing the proof?


Integration of Lambert W function logarithm.

The infinite power tower or infinite tetration ${\displaystyle z^{z^{z^{\cdot ^{\cdot ^{\cdot }}}}}\!}$ is generally expressed in terms of the Lambert W function in the following form:  ${\displaystyle {\frac {W(-\ln(z))}{-\ln(z)}}}$  Considering the integral  $\displaystyle \int -\frac{W(-\ln (z))}{\ln (z)} \, dz,$  Does this integral have a closed form solution?  Is there a series expansion for this integral?


Why do electrical systems have neutral, live and ground when electronic systems have only VCC and ground?

Wouldn't it be simpler if electrical systems take away the neutral and just have live and ground similar to electronic systems?


Pass a path with space to a batch file as a parameter

In first.bat, I use  var5=C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\bin\x86_amd64\ CALL scripts\vc64.bat %var5%   And in scripts\vc64.bat, I use  SET var6=%1vcvarsx86_amd64.bat CALL %var6%   But I get : 'C:\Programvcvarsx86_amd64.bat' is not internal or external command..... error.  If the path assigned to var5 has no space, then it is fine.  I tried several combination of quotations and %1vcvarsx86_amd64.bat, but no change.  How do I make it works with path with spaces?    To be more precise, suppose it is C:\a b c\  In first.bat:       SET var6=C:\a b c\  =====>  '"C:\avcvarsx86_amd64.bat"' is not.....`      SET var6="C:\a b c\" ====>   There should not be a b      SET var6=C:\a\ b\ c\ ====>    Can't find the specified path      SET var6=C:\a b c\ + Using "%var6" ====> There should not be a b     Update: Here is an example. Change a b to ab works.  call.bat in C:\  @ECHO OFF  SET var5=C:\a b\ CALL C:\1.bat "%var5%"  pause   1.bat in C:\  @ECHO OFF  SET var6=%~1Test.bat CALL %var6%  RMDIR /S C:\NoWorry   Test.bat in C:\a b Test.bat in C:\ab  @ECHO OFF  RMDIR /S C:\ThereIsNoSuchFolder


Wrong verbiage in error alert message while suggesting edits

I was suggesting an edit to a question, while submitting it says:     Oops! Your answer couldn’t be submitted because:   Should this read as Your edit suggestion couldn’t be submitted or better verbiage?


Mac turns off randomly and has lines on screen

For some reason my iMac keeps turning off around 5 to 10 minutes into boot.  Also just recently it turns on but has shaded lines going down the screen. I have not installed any weird programs and i have not used it in around 3 months.   Any ideas on what the issue is, i don't have any other information about the issue besides whats happening when i use it.  The image i'm showing you was found on google but this looks exactly like mine does.  The model of my imac is the late 2011 model.


Say I have an ID row (int) in a database set as the primary key. If I query off the ID often do I also need to index it? Or does it being a primary key mean it's already indexed?  Reason I ask is because in MS SQL Server I can create an index on this ID, which as I stated is my primary key.  Edit: an additional question - will it do any harm to additionally index the primary key?


how to prove the limit of the sequences exist?

suppose ${x_n}$ is a numerical sequence such that $$0<x_{n+m}\leq x_n+x_m$$ for all $n$ and $m\in \mathbb{N}$ and $x_1>0$. Prove that  $lim_{n\rightarrow \infty }\frac{x_n}{n}$ exists.


The stoplight turns green if there (is/are) more than 1 car(s) waiting   I'm having a bit of trouble figuring out the above statement. Which configuration is correct?  This is odd, as I'm a native English speaker in my mid-twenties, and I like to think my vocabulary and understanding of the English language is pretty good...but I'm always willing to learn!


How to produce multiple maps with same layout for different layers' extents?

I have an area which is divided into several zones the borders of which I have defined as separate layers.  The layers are defined by sql queries on a postgis table of line segments joined with a table that says which segments are part of which zone boundaries.  What I want to do is produce a set of maps where each map is a zoom to layer extent for each zone and which has standard header, legend and scale (which will preferably vary with the zone but could be fixed across all maps).  My first attempt was to get a new composer for each map -- that worked but was rather tedious.  Next I tried producing one map and printing it and then deleting the map frame and going into qgis to zoom to the next layer extent and make the boundary visible then hopping back into the composer to load it in.  This worked more or less.  Map was fine, legend was OK because it was the same for all the maps and the zone name was easy to edit but the scale needed to be deleted and set up again for each map.  Next I looked at Atlas Generation.  The manual seems to assume that you know how it works and all you need is a reminder about the details (like so many software manuals ;)  It seems to assume that you have something that you are iterating over but I can't see how to make it work -- there is nothing to iterate over to get the layers.  Any suggestions welcome!!  :)  Russell


What happens when a Shapechanged Dragon enters an Antimagic Field inside a narrow space?

A rather simple question: if an Ancient Dragon uses it's Shapechange ability to transform into a medium-sized humanoid, and then has that Shapechange disabled/dispelled inside a narrow tunnel / small underground room, will they get crushed to death by their own size? I have plans on True Poly-ing my spellcaster PC into a Dragon, and i'm worried that a random dispel would instakill me when i go dungeon-delving in the Abyss or somewhere.


Not long ago I suddenly received 100 points in every Stack Exchange site I was a member of. I got 100 points just for signing up in Meta Stack Exchange.  Is this a glitch, or a planned change?


How to add a pattern from a 2D image on a 3D object?

I am new to blender.   I have a 3D object that are made from an SVG file.  I want to know how to apply an image to said object. To act like a skin for said 3D object. This is the same as creating a clipping mask in Adobe Photoshop.  How do I apply said image to an object to make it act as a skin for the 3D object?


There exists an EICAR anti-malware test file. It is basically just a short string and looks like this:  X5O!P%@AP[4\PZX54(P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H*   You can read more about it on . That linked page states that:     The file is a legitimate DOS program, and produces sensible results   when run (it prints the message   "EICAR-STANDARD-ANTIVIRUS-TEST-FILE!").   My question is how can I run it? First I have to disable my anti malware utility so that I can save it to a file. After that I'm not sure what to do with it in order to run it.    Obviously its not going to work as an exe file since it doesn't start with 'MZ', but I can't get it to work as a com file either. I get "This version of {filename} is not compatible with the version of Windows you're running". My flavor of windows (Win7 Pro) should be able to run both 32 and 64 bit programs.  I understand that its intended use is to verify that anti malware software is working as expected, but I want to understand what the file itself does.


I really love Notepad++ and I haven't found an alternative for it yet. TextMate and TextWrangler aren't quite there yet. Specifically,  two things that I want that are not in TextMate:   variable highlighting bracket highlighting   Can you suggest an alternative editor for OS X?


It's not important if it rains or not.   Does this sentence sound odd to you because of using 'if' instead of using 'whether'?


Let $X$ be a metric space and $Y$ a topological space. Then for any map $f: X\to Y$, $f$ is continuous at point $x\in X$ if for every sequence $\{x_n\}\subset X$, $\lim_{n\to \infty}x_n=x\Longrightarrow \lim_{n\to \infty}f(x_n)=f(x)$. My question is, if we weaken the condition and let $X$ be a common topological space, does the extended proposition still hold? Thanks in advance.


If I said, "I will run, not if it is snowing, if I my shoes are comfortable." Does the "if my shoes are comfortable" modify the "I will run" clause? I agree the sentence would be clearer with the addition of "and" in place of the comma. However, without the "and" is it still clear that the "if my shoes are comfortable" clause modifies the "I will run" clause?


How do I find out the total number of accepted answers?

Can someone please suggest a query to directly see the number of answers I posted that were accepted. Right now I have to manually count from total given answers.  Hope there is an easy way.


Without which, we would be able to act at all.   I’m hearing this in my own head as, “Without which, we would not be able to act at all.”   So I'm wondering, is the former just a cleaner and less hectoring version of the second, with both meaning the same thing?


Position of "only" in “We 𝒐𝒏𝒍𝒚 have two possibilities”

Is there any difference in meaning between the three following sentences?   We only have two possibilities. We have only two possibilities. We have two possibilities only.   I have already read  and I know that the position of only and the emphasis (written or oral) may change the meaning of some sentences, but I am not sure if it does here.  Note: It is clear that “only we have two possibilities” has a different meaning. My question is restricted to the sentences I’ve listed above.


When there is a noun phrase with "or" with 1 singular noun and 1 plural noun, should the verb be singular or plural? Example: "UPS or others"

Example Sentence:     Can Amazon stock go down if the UPS or other Amazon shipping partners suddenly jack up their shipping prices?   Is it plural, jack, or singular, jacks? Usually with two singular nouns combined by or, I'm pretty sure it's a singular verb like The book or pen is in the drawer. But how about two nouns, one singular and one plural, combined by or?


Destroying opponent's creatures with hexproof

If my opponent has an abundance of other creatures including  out, can I play cards like , , or the new  to get around my opponents creatures? Since they each target all of certain types of creatures and not the individual creature itself?  Or would Hexproof prevent this since the cards don't target ALL creatures?


Why does the Software Updater allow me to update the package list without authentication unlike in Terminal?

I have found recently that when running the Software Updater GUI it automatically, without asking for authentication, updates the local package list, but when running the equivalent in Terminal (apt-get update, or apt update) I get:  E: Could not open lock file /var/lib/apt/lists/lock - open (13: Permission denied) E: Unable to lock directory /var/lib/apt/lists/ E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied) E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?   So how come through the GUI way you can do the equivalent to apt-get update, and have it run without it asking you for authentication, and in Terminal by simply typing the commands, you cannot?  Is it that the two processes are in fact slightly different, and I am misunderstanding something? Or what? How can I sort of simulate this behaviour in Terminal so that I can run the update command without the GUI (or possibly with if absolutely necessary) and without authentication?


How many elements π in $S_n$ such that $π^2 = e$ , (the order of π is 1 or 2)?

For example in $S_3$, there are 4, namely: e , (01)(2), (02)(1), and (12)(0).  In $S_4$ , i think there are 1 + 6 + 6 = 13.   The identity e: gives 1, Permutation in the form of (ab)(c)(d) : 6, In the form of (ab)(cd) : 6  But i had a feeling it must be 14 or something even... (Because 4! - 13 = 11 which is cannot be partitioned in pairs) What am i  missing ?  Also, Is there a way to dertermine how many such element in $S_n$ ?  Tnk u in advance


Let $x,y,a,b$ be real numbers.  For $x<y$ and $a<b$, show the cardinality of $[a,b]$ equals the cardinality of $[x,y]$.  I did the above problem, by defining a linear function as a bijection between the intervals. The next part of the problem states,     Extend your result (from above) to open and half-open intervals.    I'm just not sure what exactly I'm supposed to do next, the question seems vague. Am I supposed to show $(a,b)\sim (x,y)$? $[a,b]\sim (x,y)$? $[a,b)\sim (x,y]$?


Can someone give an intuitive way of understanding why Gauss's law holds?

is an amazing law. It is extremely useful (as far as problems framed for it are concerned :D. I do not have a real world-problem solving experience of using Gauss' Law).  However, I don't really understand why it works. What my doubt is, is this:     In the God-equation:      $$ \oint_s\vec{E}\cdot d\vec{s} = \dfrac{q_{enc}}{\epsilon_\circ} $$      $\vec{E}$ is the field at the area element $d\vec{s}$, and that field   is due to all the charges in the configuration. But the $q_{enc}$ is   the algebraic sum of only those charges that are enclosed within the   Gaussian surface. That is, to the net flux, only those charges affect that are within the surface. The contribution of the outside charges somehow cancels out. Why does it work that way?   If I knew a lot of advanced math and vector spaces and such fancy stuff, I wouldn't have asked this question. I am looking for an intuitive way of understanding its proof - if it is possible to understand without that depth of math. I do know some basic integration and surface integrals and all that (otherwise I wouldn't be able to use Gauss's Law, obviously!). So, if your answer involves these things, I'd be fine. But please don't bring in the divergence theorem etc. I tried to decipher the math behind it on wikipedia, and didn't understand a thing.


Find Shapefiles for world map, country borders and ISO3

I am trying to look for a source of clean Shapefiles in .shp format with country borders, for every country around the globe.  Would you be able to point me to an online free source?


Bounded sequence. What's the best constant $c$?

Let $(x_n)_{n \geq 1}$ be a sequence with $x_1=1$, defined by \begin{align*} x_{n+1}=x_n+\frac{1}{3x_n^2} \end{align*} Prove that there exists a fixed $c>0$ such that $x_n<\sqrt[3]{n+c}$  I cubed the relation in order to prove that $x_n \geq \sqrt[3]{n}$, and I guess that $c$ may be $1$, but I couldn't prove it.


How can I make a filter that permanently deletes emails?

In Gmail I have a filter that automatically moves all the mails from one address to the trash folder. I want to permanently delete them by even skipping that folder.  How can I block all messages from an email address so that I'm not even able to read them?


Can I use competing in this reframed sentence?

I was reading a newspaper and then I came across this sentence:     "The restaurant owner is competing more for guests than for the staff members."   So can I reframe it in this way      "The restaurant owner is competing more for guests than competing for the staff members."


I'm new to this site but I have found many good answers on this site before. I have also searched for my actual question but I didn't found the answer or at least I didn't understand what should I do for that.  The topics I have already read:        And many more I found on google.  Problem :  We have a dedicated server with 16 IP addresses, we use 4 IP addresses actually, 1 is main IP, 2 for NS's and 1 for mail server.  So in our DNS config file we have :  lynxis-sa.eu. 86400 IN NS ns01.lynxis-sa.eu.   lynxis-sa.eu. 86400 IN NS ns02.lynxis-sa.eu.  ns01.lynxis-sa.eu. 14400 IN A IP2   ns02.lynxis-sa.eu. 14400 IN A IP3  ptr00.lynxis-sa.eu. 14400 IN A IP1   ptr01.lynxis-sa.eu. 14400 IN A IP2   ptr02.lynxis-sa.eu. 14400 IN A IP3   ptr03.lynxis-sa.eu. 14400 IN A IP4    lynxis-sa.eu. IN A IP1  localhost.lynxis-sa.eu. IN A 127.0.0.1  lynxis-sa.eu. IN MX 0 smtp.lynxis-sa.eu.   lynxis-sa.eu. IN MX 10 mail.lynxis-sa.eu.  smtp.lynxis-sa.eu. 14400 IN A IP1 (For ssl)   mail.lynxis-sa.eu. 14400 IN A IP4      Hostname : s1.lynxis-sa.eu   The Reverse for each IP is correctly set on IP manager as same you can see here.  I manage a VPS with exactly same configuration but with one IP and everything is ok. But on this server, with every MX Lookup on , I get the warning message "Reverse DNS does not match SMTP Banner".  For info: we use Centos 6 and Centos Web panel.  Thank you for your help in advance :)  For other people who may have same problem, the answer is :


What's the point in saying "I could care less"?

To care less would mean the caring is more, having room to care less.


Accidentally set shortcut for vertex select to left mouse. How do I undo this?

I was trying to set it to one of my programmable keys on my keyboard but I messed up and made this happen...  Can I undo?


I tried to make a game where you can destroy something when you swipe or tap. However, it says NullReferenceException & while the swipe control actually works, the gameobject can't be destroyed.  public class checkUp : MonoBehaviour { private Swipe swipe; private UIManager uiManager;  private void Awake() {     swipe = GetComponent<Swipe>();     uiManager = GetComponent<UIManager>(); }    // Update is called once per frame void Update() {     if (swipe.SwipeUp ) //NullReferenceException: Object reference not set to an instance of an object     {         Debug.Log("Passed!");         uiManager.destroyed = true;         Destroy(gameObject);     }   Here's the partial code from swipe:      if (swipeDelta.magnitude > 125)     {         //which direction?         float x = swipeDelta.x;         float y = swipeDelta.y;         if (Mathf.Abs(x) > Mathf.Abs(y))         {             //left or right             if (x < 0)                 swipeLeft = true;             else                 swipeRight = true;         }         else         {             // Up or down?             if (y < 0)                 swipeDown = true;             else                 swipeUp = true;         }     }


I want to know to browse files from iPhone with Bash Terminal or other tools on Mac.  Does anybody of you know how to do this ?  Thank you for your answers


Before I removed Windows 7 from my computer and replaced it with Ubuntu, I had over 257 threats that never would go away. I don't know if the trojan horse I had also could transfer over to Ubuntu. Can my computer be infected? I'm trying to be very careful when I use my computer, because I don't want to get a new computer.  I've only had Windows 7 and my PC, for only a few years. First, I took it to  and they said a trojan horse is supposed to be on the computer. The man only "looked" at it and since he put it in factory settings, it hid and stole my PC twice in a row. Then, I took it somewhere to someone I know and they re-built it. But it had tons of issues again.  My anti-virus and my programs and other files were disappearing right before my eyes. My Wi-Fi was turned off, and I couldn’t turn it back on. It even shut down by itself. And it never did that before.  Will my infections from Windows 7 transfer over to Ubuntu? Just remember I don't have windows 7 any more, I only have Ubuntu.


None of the characters visible in any window of Ubuntu 18.04

I updated from 16.04. All files were downloaded, but after installation for several hours(almost all were installed), update manager froze of about 3 hours. I killed the upgrade manager and rebooted. Now it starts in ubuntu 18.04, but none of the characters are visible as shown in image below:  even the command line is not visible:  Only xterm is visible. Chrome is also working fine.


Why not define a "Dolbeaut complex" with $\partial$ instead of $\overline{\partial}$?

Yesterday I saw the definition of Dolbeaut cohomology: let $(M,J)$ be a complex manifold, write the exterior derivative as ${\rm d} = \partial +\overline{\partial}$, where $\partial: \Omega^{\ell,m}(M) \to \Omega^{\ell+1,m}(M)$ and $\overline{\partial}: \Omega^{\ell,m}(M) \to \Omega^{\ell,m+1}(M)$, look at the complex $$\cdots \xrightarrow{\hspace{.4cm}\overline{\partial}\hspace{.4cm}} \Omega^{\ell,m-1}(M)\xrightarrow{\hspace{.4cm}\overline{\partial}\hspace{.4cm}} \Omega^{\ell,m}(M) \xrightarrow{\hspace{.4cm}\overline{\partial}\hspace{.4cm}} \Omega^{\ell,m+1}(M)\xrightarrow{\hspace{.4cm}\overline{\partial}\hspace{.4cm}} \cdots$$and put $$H^{\ell,m}_{\rm Dolbeaut}(M) \doteq \frac{\ker(\overline{\partial}: \Omega^{\ell,m}(M) \to \Omega^{\ell,m+1}(M))}{{\rm Im}(\overline{\partial}: \Omega^{\ell,m-1}(M) \to \Omega^{\ell,m}(M))}.$$Great.     Question: Why did we took the above complex instead of $$\cdots \xrightarrow{\hspace{.4cm}\partial\hspace{.4cm}} \Omega^{\ell-1,m}(M)\xrightarrow{\hspace{.4cm}\partial\hspace{.4cm}} \Omega^{\ell,m}(M) \xrightarrow{\hspace{.4cm}\partial\hspace{.4cm}} \Omega^{\ell+1,m}(M)\xrightarrow{\hspace{.4cm}\partial\hspace{.4cm}} \cdots?$$   I get that $f: M \to \Bbb C$ is $J$-holomorphic if and only if $\overline{\partial}f = 0$ so that $\overline{\partial}$ sort of measures how stuff in general would be away from being holomorphic. But I'd like a more solid explanation.


I am a bit confused in understanding the casting concept in java. Here is a piece of code that I have written.  class Parent {     public int a = 5;     public void print()     {         System.out.println("a :: " + a);     } } class Child extends Parent {     public int b = 10 ;      public void printMe()     {         System.out.println("a :: " + a + " b::  " + b);     } }  public class Main  {     public static void main(String[] args) {          Child b = new Child();         Parent a = (Parent)b;         Child b1 = (Child)a;         b1.printMe(); // This piece of code works fine. There is no exception           Parent a1 = new Parent();         Child b2 = (Child) a1;         b2.printMe(); //This piece of code throws a java.lang.ClassCastException     } }   In the first piece of code I am creating a child object and typecasting it to parent. When I typecast the parent object to child again It works fine. But in the other piece of code I am creating a Parent object first and then typecasting it to child. Compiler doesn't show any error. But when I run the code It is throwing ClassCastException. Can someone explain me why is it so ? If there is no problem with first piece of code means second one also should work fine right ? I am so confused. And one more question is when do we assign a child object to a parent reference ? I mean for example if we write a code like below  Parent p = new Child();   which is equal to the following code right ?  Parent p = new Parent();   Then what is the benefit in writing such code ?


Is it possible to do 50 km distance without any previous training?

I'm considering to do a 50-55 km distance on a mixed surface. Mostly asphalt and gravel, maybe even a little bit of sand. Haven't done any training or exercise, basically been sitting at home all day, everyday for years. Don't know why but suddenly had an urge to go on a journey.  My bicycle is quite old, 12 or so years, not in a great condition either but nothing is falling off so far. That wouldn't be my concern though, my concern is will my legs be able to cycle for 50 km in one go without any previous leg training. Is it advisable for me to do this? Will my legs be stiff after the first 10 km? What do you guys think?    Edit  I'm 24. Last year I tried a 30 km distance, my legs were gone after 20 and I had to step off my bicycle and walk a bit, as it seemed easier than cycling. That was my only real exercise I've done in a couple of years.  I really have all day and can take as many rests as I want. I'd say I have a solid 8 hours. Is it doable if I go on a gear that doesn't require a lot of push?


So, I started playing Mass Effect 3 and I imported my saved game from Mass Effect 2, I had a romance with Tali and I wanna know that even if I imported the romance within the saved game, am I able to romance somebody else in the game or will I have to continue romancing Tali?


Isomorphisms preserving integral domains and fields

Let $R \simeq S$ be isomorphic commutative rings with unity. Prove the following:  a). If $R$ is an integral domain then $S$ is an integral domain.  For this, I said that If I let $f: R \to S$ be an isomorphism and $(R, + , \circ), (S, \oplus, \ast)$, then let $x, y\in R$,  such that $x \circ y = 0_R$, because $f$ is an isomorphism, $f(x \circ y) = f(x) \ast f(y) = f(0_R)$. If I let $R$ be an integral domain then, as per the definition $R$ is commutative, has unity, and no zero divisors.   So $f(x \circ y) = f(x) \ast f(y) = f(0_R)$ where we have either $f(x \circ y) = f(0_R) \ast f(y) = f(0_R)$ or $f(x \circ y) = f(x) \ast f(0_R) = f(0_R)$.   Since $f$ is an isomomorphism, let $s = f(x), t = f(y)| s,t \in S$. Then $s \ast t = f(0_R)$. By definition, $S$ also has unity so $0_S$ exists. If we map $0_R \to 0_S$. Then either $s = 0_S$ or $t = 0_S$.   So then, since $S$ has unity, is commutative, and has a no zero divisors as we showed above, it is also an Integral domain.  I'm not sure I have this correctly.  b). If $R$ is a field then $S$ is a field. I don't really understand how to do this one. Since $S$ is an integral domain, it has a $0_S$. So I need to show that $S$ distributes $\ast$ over $\oplus$.  Any help with these is appreciated


$\mathop {\lim }\limits_{x \to \infty } f\left( x \right) = L$ Prove $\mathop {\lim }\limits_{x \to \infty } f'\left( x \right) = 0$

Let $\,f:\left[ {0,\infty } \right) \to \mathbb R$ be a continuously differentiable function such that $$ \mathop {\lim }\limits_{x \to \infty } f\left( x \right) = L~~and~~~\mathop {\lim }\limits_{x \to \infty } f'\left( x \right) = K $$  Both limits exists and finite.     How can I prove that $K=0$?   My try:  Assuming $K\ne0$. W.L.O.G:     $k\gt0$ .   If that's the case then then $\mathop {\lim }\limits_{x \to \infty } f\left( x \right) = L$ doesn't exist because the derivative is positive around $K$ and that is not possible because $f(x)$ would keep increasing over $L+\epsilon$ for all $\epsilon$. How can I formalize that?


If $f(x + y) \leq yf(x) + f(f(x))$ for all real numbers $x$ and $y$, then prove that $f(x) = 0$ for all $x ≤ 0$.

The Problem:   Let $f : \mathbb R \to \mathbb R$ be a real-valued function defined on the set of real numbers that satisfies $$f(x + y) \leq yf(x) + f(f(x))$$ for all real numbers $x$ and $y$.  Prove that $f(x) = 0$ for all $x ≤ 0$.  (IMO $2011$ , Pr: $3$)  Here is the solution:  Before we prove that $f (x) = 0$ for all $x ≤ 0$, we will prove that $f (0) = 0.$ $\color{black}{\large\text{Case} \thinspace  1:}$ $f(0)>0$ Let, $\varepsilon >\dfrac{f(f(0))}{f(0)}$ and $x<- \dfrac{\varepsilon+f(f(0))}{f(0)}$  we have, from $f(x)\leq xf(0)+f(f(0))$,  $f(x)<-\varepsilon.$ Then from, $f(f(x))\leq f(x)f(0)+f(f(0))$ we have $f(f(x))<0$. Finally,  since $0<f(0)\leq f(f(0))$ ,we get $f(0)\leq-xf(x)+f(f(x))<0$ which imply $f(0)<0$, which gives a contradiction. $\color{black}{\large\text{Case} \thinspace  2:}$ $-\alpha \leq f(0)<0$, where $\alpha\in\mathbb{R^+}.$ From $f(x + y) \leq yf(x) + f(f(x))$ we have: $\begin{cases} f(x)\leq f(f(x)) \\ f(x) \leq xf(0)+ f(f(0)) \end{cases} \Longrightarrow f(x)\leq f(x)f(0)+f(f(0)) \Longrightarrow f(x)(1-f(0))\leq f(f(0))$. Then applying $x=f(0)$, we get $f(f(0))\leq 0$, which imply $f(x)\leq 0$, which gives $f(f(x))\leq 0$. In this case, we have $f(x)<0.$ Because, if $f(x)=0$ at least for some $x$, from $f(x)\leq f(f(x))$, we get $f(0)\geq 0$, which gives a contradiction. Then let, $x<-\sqrt {\alpha}$,  from  $f(x + y) \leq yf(x) + f(f(x))$  we have: $$\begin{align} f(z)\leq(z-x)f(x)+f(f(x)) \Longrightarrow f(f(x)) \leq (f(x)-x)f(x)+f(f(x))\Longrightarrow f(x)(f(x)-x)\geq 0 \Longrightarrow f(x) \leq x <-\sqrt {\alpha} \Longrightarrow f(x)< -\sqrt{\alpha}.\end{align}$$ Finally, from $f(0)\leq-xf(x)+f(f(x))$ we get $f(0)<-\alpha$, which gives a contradiction. So, we deduce that $f(0)=0$. Then, applying $f(0)=0$, from  $f(0)\leq-xf(x)+f(f(x))$ and $f(x) \leq xf(0)+ f(f(0))$ we have, $$\begin{cases} xf(x)-f(f(x)) \leq 0 \\ f(x) \leq 0 \\ f(f(x)) \leq 0 \end{cases} \Longrightarrow  \begin{cases} xf(x)\leq0 \\ f(x)\leq 0 \end{cases} \Longrightarrow \begin{cases} xf(x)\leq0, x\in\mathbb {R} \\ xf(x)\geq 0, x\leq 0 \end{cases} \Longrightarrow xf(x)=0, x\leq 0 \Longrightarrow \color{blue} {\boxed{ f(x)=0, \text{for all} \thinspace x\leq 0.}}$$ End of the Proof.  Can you verify this solution? Are there any mistakes, gaps, etc.? Thank you very much!


How can I check if a string ends with a particular character in JavaScript?  Example: I have a string   var str = "mystring#";   I want to know if that string is ending with #. How can I check it?   Is there a endsWith() method in JavaScript? One solution I have is take the length of the string and get the last character and check it.   Is this the best way or there is any other way?


I am working for a project in netbeans. When i'll finish my project how can i execute my application (out of Netbeans)? I'm working for a little and simple guide of a game.


UK visit visa for a job interview- financial and employment proof

I am an Indian citizen. I plan to go to UK for an onsite job interview with an overnight stay and return back to India next day. I need an advice regarding  financial documents submission.    I am an unemployed person, but I have a job offer for which I can submit job offer letter.  I am aware about personal financial documents submission for which I can submit bank statements which shows that I have enough balance for a one day stay, but a trust in India is sponsoring my travel to UK for air and visa expenses. Is it OK to submit their letter of sponsorship with their registration number or will be my application be refused on this ground?


Why does an infinitely decreasing resistance infinitely increase current?

So I have been mulling over Ohm's law for hours today. It makes sense to me that the current gets bigger as voltage rises, since the voltage is supplying more electrons and current is the number of electrons flowing. However, I'm confused by the theory that as resistance drops, current increases, even when voltage stays constant. Such as:  $$V/R = I$$ $$\frac{1V}{0.0001 \Omega} = 10,000,000 mA!!$$  That's a big current from such a small voltage!  My mental picture of a current is more electrons flowing. Electrons are supplied by the voltage, right? If we start off with a small voltage, say 1V, but infinitely decrease the resistance, we'll get a bigger and bigger current. How can this be? Isn't current the number of electrons flowing? With fewer electrons (because of less voltage), how can less resistance infinitely increase the current?


Do I need to mention 'has' ( present perfect tense) twice when connecting the sentences with and?

Is this sentence correct as is, or should I remove the second has since that phrase is connected to the preceding one with and?     As Mr. X has replied your email and has requested the 'PDF files' of the project, here please find attached the requested files.


UPDATE:  The "screen: flip region" command from the Menu Search is either accidentally or intentionally missing from both stable, beta, and experimental versions of Blender 2.90.  Downgrading to Blender 2.8x has solved this problem for question A, however even though the Flip Region command can be executed on the panel in question B, it doesn't actually do anything. :( A.  I am trying to move the Toolbar to the right hand side of the screen.  Is this still possible in Blender 2.9? In scrolling through the forums, it appears that pre-2.8 there was a "flip side" feature on the toolbar that could be accessed by the search bar with F3. However the feature doesn't appear to exist post 2.8, likely due the appearance on forums that many people were doing this unintentionally and coming here for help reversing it.  Maybe I need to look in a new place?  Any information is appreciated. B.  Similarly I would like to move this. (I'm not sure what its called so for this post I'm calling it Tool Properties).  Is there a way to move or scale up the Tool Properties or view them in the larger Editor Properties panel as highlighted? Additionally if someone knows the proper name of the panel please let me know.  I apologize if these questions have been answered already.  I attempted to find solutions myself but have come up empty. Thanks, Ryan


2.5 GB usable RAM out of 4GB both in Linux and Windows

I have a Lenovo laptop that came with a 4 GB ram installed in one of its two slots. It supports upto 8 GB distributed in the two slots. It worked fine. But one day I noticed that my laptop is getting very slow and checked the available RAM in the windows task manager where it should 2.57 GB usable out of 4 GB, 1.4. GB system reserved. I thought it was a windows problem and did research online but nothing solved my problem. Now I am on Linux but the same case here. Whether I use a 32bit system or a 64 bit one, whether I place the ram in other slot or place a new RAM there. The problem remains the same. When I use the existing RAM with another 4GB in the remaining slot, it shows 6GB instead of 8. I checked the same laptop of my friend and it works just fine. My BIOS settings, version everything is exactly same as my friend's Laptop. Can anyone tell me what is the problem here with my PC


Is it possible to avoid awarding a bounty on a low quality post?

I got only one answer to my question and it doesn't answer the question. After IMMENSE research I found my own answer and posted it.  BUT  The question has a bounty. This bounty is automatically going to be forever rewarded to a low-effort post.  I can't award my own answer, so is there a way to avoid awarding low effort?  Note: I accept the cost of the bounty. This is a question about where the benefit goes - the "award." I found it in the community wiki section about Automatic Awarding.


Blender basic , selecting and merge objects

I am novice, I saw several post saying that for merge you need to select all ( pressing A) and then Control+J  but in my case it doesnt work (I think that is because are separated objets) I added a screenshot with better explanation    I have downloaded learn to paint it,I need to merge both objects to UV unwrap


Abstraction VS Information Hiding VS Encapsulation

Can you tell me what is the difference between abstraction and information hiding in software development?  I am confused. Abstraction hides detail implementation and information hiding abstracts whole details of something.  Update: I found a good answer for these three concepts.  for several citations taken from .


Should you add AM or PM after a 24 hour time?

Say you've written 16:00 PM. Is that correct? Is the PM necessary?


What are SQL injection attacks on SQL Server? How can we prevent them?

What are SQL injection attacks on SQL Server? How can we prevent that ?


Proving by strong induction for a sequence of integers, $2^n$ divides term $n$

Provided the following sequence of integers $t_1, t_2, t_3$,... is defined as:    $t_1 =4, t_2 =8$ and $t_n= $ $ 6t_n$$_-$$_1$ - $4t_n$$_-$$_2$ for all integers $n \geq 3$   How do we prove that $2^n$ divides $t_n$ for all integers $n \geq 1$ by strong induction?  So far, I am having problems with the induction step as I am still trying to grasp the concept of strong induction, but this is what I came up with so far:  Base step:  $t_3 = 32$, which is divisible by 8; and $t_4 = 160$, which is divisible by 16.  $\therefore$ Statement is true when $n=3$ and $n=4$.  Induction step:  Assuming $k=n$ and the statement is true for $3,4,...k$. Prove that $2^k$ divides $t_k$ for $k+1$:  $t_3 = ((2^3 - 2)(2^3) - (2^2)(2^2)) = 2^6 - 2^4 - 2^4 $; dividing this by $2^3$ gives $2^3 - 2^2$ which would be an integer result.  $t_4 = ((2^3 - 2)(2^5) - (2^2)(2^3)) = 2^8 - 2^6 - 2^5 $; dividing this by $2^4$ gives $2^4 - 2^2 - 2$ which would also be an integer result.  $\therefore$ By the logic above, the statement also holds for $k-1$, $k$ as well as $k+1$, thus as required to prove by strong induction.  I believe this is a fundamentally flawed way of trying to prove by strong induction, but this is the only way I can possibly think of. Can someone show a correct method of solving this?


Pumping Lemma for $L=\left\{0^i 1^{j} \mid \gcd(i,j) = 1\right\}$

Let $L=\left\{0^i 1^{j} \mid \gcd(i,j) = 1\right\}$ I want to prove that this is not a regular language, but I am having trouble finding a string I can pump resulting in the string not being in the language. Ideally, rather than a full solution, I'd like suggestions for a string that I could use in this proof. I've played with the idea of setting $j = 2$ and $i = 2n+1$, but I don't think that would work.


Who or whom in "by other people whom I know"?

Should who or whom be used in the following sentence?      All the swans seen by other people whom I know have been white.   My first thought was whom is correct because it's part of a prepositional phrase, but there's a lot going on in that phrase, and so now I'm not sure.


Calculating the integral of an infinite product

I came across the following question which asked     Prove that $$\int_{0}^{1} \prod_{k=1}^{\infty} (1-x^k)=\frac{4\pi\sqrt{3}\sinh{\frac{\pi\sqrt{23}}{3}}}{{\sqrt{23}\cosh{\frac{\pi\sqrt{23}}{2}}}}$$   Note: This is the one of the first integrals I  have seen like this. I have been looking up other questions (similar to mine) and am still unable to figure out a method to try.  Attempt: I first examined different cases for $k$ and I am able to compute those integrals fine, since they are just polynomials when expanded.  However, I am still stuck with where to begin.  $$\int_{0}^{1} \prod_{k=1}^{\infty} (1-x^k)=(1-x)(1-x^2)(1-x^3) \cdots (1-x^n) \cdots$$  If I were to factor a $-1$ from each term I can see that each term, after the first, contains a factor of $(x-1)$ which might help with some kind of substitution, but that is about as far as I got.   If someone could please offer a hint that will help me get going with this problem.  Thank you.


Transforming the independent variable for better prediction results with decision tree and random forest

I am trying to predict the amount a customer will pay. Removed zeros and standardized key columns. Data looks like this  The distribution of a dependent variable is very skewed.  I tried to apply three methods:  log square root Box-Cox  None of them satisfies me. Log transformation skewness is -0.9497961701603782  Square root transformation skewness is 3.933253401700889  Box Cox transformation skewness is 0.13615956299065202  Log transformation gave me the best RMSE so far.  0.95 for train and test RSME and CV (decision tree) 0.75 for train and test RMSE (random forest)  What else can I try here? My only guess - start to add variables, which I dropped before, some of them were highly correlated. Thanks, appreciate any tips.


MCP4131: How to know what value resistors to use on the multiplexed SPI IO?

There are two aspects here. The first question is related to R1 below:    The datasheet says: "R1 must be sized to ensure VIL and VIH of the devices are met" but gives no formula. So first question:  (1) How does one determine value of R1?  The datasheet gives maximum SPI SCK frequency for this device as 10MHz for 5V supply as given in Tables 1-1 and 1-2. However, for the read operation on the device where the SDI/SDO are multiplexed, the idea is different because:    The point 2 under the Table above says that the max SCK can be increased by using a pull up resistor. About these things I am wondering the following:  (2) Why is max SCK frequency lower for multiplexed SDI/SDO read operation only? (3) If I connect a pull-up resistor it will certainly form a voltage divider with the R1 in the first picture. How do I determine the value of both of these resistors then?  Finally, since the Table 1-1 and 1-2 give SCK Input Frequency for voltage 1.8V to 2.7V as 1MHz rather than 10MHz which applies to 2.7V to 5.5V.   (4) Why is the max SCK lowered at lower supply voltage?


Is $\mathbb Q$ finitely generated as a $\mathbb Z$-module?   If I were to take a guess, I would say no but only because I am not sure how to generate all of $\mathbb Q$ from a finite set. But is this possible?


If I type   svn info|grep Revision   I get the latest revision in all branches, but how do I get the latest commit only in the main trunk?


SQL statement sequential execution for multiple statments

If a single SQL file contains 2 SQL statements below each other (as below) for millions of records  Query 1 : select Id into MyTempTable from TableB b join abc a on a.Id = t.Id   Query 2 :  Update TableB set Completed =1  Is there any chance that query 2 will execute first for some of the records or do we have a guarantee of sequential execution of those statements?  In another words, will Query 2 execution be started only after Query1 finishes?


In the case of forced, undamped oscillations, why is the amplitiude of the steady state oscillations bigger, when the frequency of the driving force gets closer to the natuaral frequency of the oscillating system. I know, that we can get this result by solving appropriate equation, but I am looking for an intuituive explanation. I know the "kid on a swing" explanationa, but it relates to driving in a form of short impulses, rather than a sinsuoidally changing force.


I know this is a subjective question, but  I need some opinions on a very good book for learning differential equations.   Ideally it should have a variety of problems with worked solutions and be easy to read.   Thanks


If photons are particles why gaps don't form between radially emitted photons even at astronomical distances?

From the title of the question You may presume what I am asking. Is there a way to get around that.For example photons from hubble deep field have travelled 13 billion light years and we still see a picture as it was 1m from us. Can something very dense vibrate and transmit the vibrations at the speed of light and photons are just these vibrations. Do conclusions from Michelson-Morley experiment predict with certainty there is no any possibility for a conductor of waves (EM and gravitational)?


Who trained Yoda in the ways of the Force?

I was looking through comics and the TV shows and I was wondering who trained Yoda in the ways of the Force. I could be wrong but I don't remember any mention of Yoda's master.


Ok guys...  I have following class  #include <functional>  template <typename TValue, typename TPred = std::less<TValue>> class BinarySearchTree {     struct TNode {         TValue value;         TNode *pLeft;         TNode *pRight;     }; public:     BinarySearchTree();     ~BinarySearchTree();      . . . private:     TNode *pRoot;       . . . };   then in my .cpp file i defined the ctor/dtor like this:  template <typename TValue, typename TPred> BinarySearchTree<TValue, TPred>::BinarySearchTree() : pRoot(0) {}  template <typename TValue, typename TPred> BinarySearchTree<TValue, TPred>::~BinarySearchTree() {     Flush(pRoot); }   my main function:  int main() {         BinarySearchTree<int> obj1;     return 0; }   and i get following linkage error:  public: __thiscall BinarySearchTree<int,struct std::less<int>>::BinarySearchTree<int,struct std::less<int> >(void)   i tried to put the constructor definition into the header file and i get no error. only if i try to define it in the cpp file.


Static variable initialization during declaration in multi-threading

I want to add the following code to my class:  static private final ILogic_P logicInstanceI =     (ILogic_P)Factory.CreateAnon("some.path.ILogic_P" + (SomeClass.isIMDB() ? "1" : "2"));  public static ILogic_P getLogicInstanceI(){     return logicInstanceI; }   I can't figure it out if the initialization of the static variable is thread safety or not. Is there a chance that two threads will try to initialize this attribute simultaneously?


How can I accept end user license agreement for ttf-mscorefonts-installer?

I was trying to install a software. This pop up appeared  And now I can not do anything, I tried to press okay but it doesn't work. What is the solution of this? Which button exactly I need to press? I'm using Ubuntu 20.04.1.


Changing the keyboard layout/mapping on both the console (tty) and X in an X/console agnostic way?

I've been able to change the keyboard layout/mapping when the  is running using ~/.Xmodmap (and I suppose you could also do it through the  directly, eg. using  as a wrapper around X protocol calls).  I've been able to do the same (somewhat) on the console/tty (ie. when X is not running) using loadkeys.     Is there a way to customize the keyboard layout similarly, but from a single source, in such a way that it affects both X and the console, ie. in a way that is "X-and-console agnostic"?   (The only way I can think of is by writing a "keyboard driver" that talks to the kernel's input interface, evdev, and sends the input you want (through uinput?), or something, but I don't know if this even makes sense, or if there's an easier way.)


12-year-old hits pregnant mother in the stomach

My partner is pregnant with my child. We were doing homework on the couch with her twelve year old daughter. All was going well when she started hitting her mother and then hit her mildly in the stomach.  I didn't react other than saying you shouldn't do that. I am concerned she might have hurt the fetus like that. The fetus is three and a half months old.  I am also concerned she might be doing that when I'm not there. My partner may not be saying anything to me to relieve the pressure.  Her daughter and son sometimes say they don't want this child we wanted.  What should I do, as a father?


What part of a sentence is that word in these kind of sentences

hi and thanks for reading. I can find many sentences which are very simple but i can't assign all of the words with the correct part of a sentence. What i mean is, in sentences such as:   She washed it clean. He shot him dead. They bled me dry   So as i already mentioned, these are fairly simple sentences that follows the simple Subject Verb Object paradigm, but what puzzles me is the adjective that follows  Are they simply an object complement as in: They elected him president ? I appreciate the help.


Problem_     $\{a_n\}$ is a recursive sequence given by setting $a_1\gt2, a_{n+1}=a_{n}^2-2, \forall n\in\mathbb N$. Then, show that $$\sum_{n=1}^\infty\frac{1}{a_1a_2\cdots a_n}=\frac{a_1-\sqrt{a_1^2-4}}{2}$$   Due to the recursive relation, we can re-write the given series as: $$\sum_{n=1}^\infty\frac{1}{a_1a_2\cdots a_n}={1\over2}\sum_{n=1}^\infty\frac{a_n^2-a_{n+1}}{a_1a_2\cdots a_n}={1\over2}\lim_{m\to\infty}\sum_{n=1}^m\left(\frac{a_n}{a_1a_2\cdots a_{n-1}}-\frac{a_{n+1}}{a_1a_2\cdots a_n}\right)\\={1\over2}\lim_{m\to\infty}\left({a_1\over1}-\frac{a_{m+1}}{a_1a_2\cdots a_m}\right)$$ Ultimately, I have to show that  $$\lim_{m\to\infty}\left(\frac{a_{m+1}}{a_1a_2\cdots a_m}\right)=\sqrt{a_1^2-4}=\sqrt{a_2-2}$$ First of all, since $a_1>2$, it is not difficult to show that $a_{n+1}=a_n^2-2>a_n$ inductically. Also, I knew that $\{a_n\}$ is not bounded above by drawing a graph of $y=x$ and $y=x^2-2$. Consequently, I thought that the only way to show this is using squeeze. But, I'm actually lost the way since it is quite hard to make an inequality(in order to use the squeeze) since the limit converges to nonzero value. Could you please suggest the idea for having the value of the limits? Thanks.


How to install Android Studio on Ubuntu?

Please tell me the full process of installing Android Studio and its necessary dependencies.


Alternating row sums of Pascal's Triangle

So, I know that, $\sum_{k=0}^n(-1)^k*\binom{n}{k} = 0$. I know the reason for this is because the summation of even subsets is equal to the summation of odd subsets and obviously $n=n \implies n-n=0$. However, I want to know 1)what and how to derive the formula for this using the definition of ($n$ choose $k$)and 2)Why the formula is what it is. I thought that maybe the formula is $(-2)^n$ since the formula for the non-alternating row sums is $2^n$ but I feel like that logic may be flawed.


What is the physical meaning of a "complete" Hilbert space in QM?

What does the word "complete" means from the physical point of view? I do not understand what it physically means to say that a  is a .


What are the fundamental differences between trapped ion quantum computers and other architectures?

There are many different ways to build quantum computers, such as superconducting qubits, quantum dots, and ion traps.  What I would like to understand is why some universities and research organizations have chosen to study trapped ion quantum computers. I understand that it is better in some respects, but what are the fundamental differences?           Source:       Domain of Science      Dominic Walliman


Why was bounty not awarded automatically in this case?

When I wrote the answer, the bounty period still had two days to go according to the message. Yesterday it started showing the "grace period has 'x' hours left" message.  Today even after the grace period has ended, it still hasn't awarded half the bounty as per the documentation. Is there some other reason for this? The question has not received enough attention?


how to shade the intersection of 3 lines

I was trying to shade the intersection of the following 3 lines, but don't know how to do that. Apparently, the coordinates of the 3 points of the triangle area are identifiable. Could anyone please help me with that? Thank you in advance.  \documentclass{standalone} \usepackage{pgfplots} \usepgfplotslibrary{fillbetween} \usetikzlibrary{intersections} \begin{document}  \begin{tikzpicture} \begin{axis}[     axis lines = left,     xlabel = $x$,     ylabel = {$f(x)$},     ymin=0, ymax=5 ] %Below the red parabola is defined \addplot [name path=A][     domain=0:4,      samples=10,      color=red, ] {2-0.5*x}; \addlegendentry{A: 2-0.5*x} %Here the blue parabloa is defined \addplot [name path=B][     domain=0:4,      samples=10,      color=blue,     ]     {(15-5*x)/3}; \addlegendentry{B: (15-5*x)/3}  \addplot [name path=C][     domain=0:4,      samples=10,      color=yellow,     ]     {5*x-15}; \addlegendentry{C: 5*x-15}  \def\firstellipse{(-4,0) ellipse [x radius=8, y radius=3, rotate=45]}   \end{axis} \end{tikzpicture} \end{document}


How to replace quotation marks in a file with sed?

I have a file that contains multiple lines of xml. I would like to replace certain parts of the file. Some parts of the file contains quotation marks (") which I would like to replace. I have been trying to escape the quotation mark with \, but I don't think this is working based on the result of my file.  Here is an example of one of my sed commands:  sed -e "s/\"text\"/'text'/ig" file.xml > temp.tmp   Is this how you escape quotation marks in a sed command or am I doing something wrong?


if I have a simple for loop like:  for i in range(10):    total = 0    total = total + i    print(total)   How can I print the loops once/together like:  1 2 3 4 5 6 7 8 9    Instead of every loop by itself:  1 2 3 etc


I recently bought a Cyclone II FPGA .  I have been able to program it with a USB Blaster cable and the Altera Quartus Software.  The problem is that when I disconnect power, I lose the program.  How do I program it so it will continue its operation after power is lost?  Note: this question is similar to  one, but the name of the question made it hard to search for, so I agree with "The Photon" that this one should be kept open.


Applying substitution to $\int \sqrt{1+\sin(x)}$

I'm having a problem with substituting when it comes to trig functions.  The integral is:$$\int\sqrt{1+\sin(x)}dx$$  Substituting: $1+\sin(x) = u \implies \frac{d}{dx} u = \cos(x) \implies dx = \frac{1}{\cos(x)}du$  So now we have the integral: $$\int \frac{\sqrt{u}}{\cos(x)}du$$  So now the question is, what do I do with the $\frac{1}{\cos(x)}$? How can I substitute that with $u$?


What is the job of dependency injection?

The concept of dependency injection is not clear to me. I read about it. What i learn is it is used to inject dependency instead of adding it. Can someone explain it to in simple way if possible with example?


How to add "open in new tab" option in CkEditor

Now, we can only add link. But our client is looking for an option in Ckeditor for adding an option to addition of "Open in NEW tab" option with Link.    Do we have any module or any trick for solution of this issue ?  OR   Do we have to alter CkEditor module ?


To create an app with Visual Studio (C#) that can password protect a PDF?

I'm working on a project where we have SQL Server Reporting Services automatically saving a PDF report to a network folder.  We then want to password protect this file and email it to specified recipients.  Is it possible to create an app with Visual Studio (C#) that can password protect a PDF?


grep'ping files for multiple strings (not necessarily on the same line)

More often that I like to admit I look for a file that contains some strings.  Currently I do:  grep -rl string1 | xargs grep -l string2 | xargs grep -l string3   Is there a tool that does this prettier?  This greps for string1 or string2 or string3.   grep -rl -e string1 -e string2 -e string3   I want files that contain string1 and string2 and string3 but not necessarily on the same line.  Maybe one of the modern greps (ag/ack/rg/sift) can do this?


Series convergence proof review (Baby Rudin)

Ch.3 #7. Prove that the convergence of $\sum a_n$ implies the convergence of $$\sum \frac{\sqrt{a_n}}{n},$$ if $a_n \geq 0$.      My attempt. If $\sum a_n$ is convergent, then by the root test, $\lim_{n \rightarrow \infty} sup \sqrt[n]{|a_n|} < 1$. This means $|a_n|^{1/n} < 1$. Because $a_n \geq 0$, this means $a_n ^{1/n} < 1$. Now apply the root test to $\sum \frac{\sqrt{a_n}}{n}$ by considering $$\lim_{n \to \infty} sup \sqrt[n]{|\frac{\sqrt{a_n}}{n}|}.$$ $$\sqrt[n]{|\frac{\sqrt{a_n}}{n}|} = \frac{\sqrt{{a_n}^{\frac{1}{n}}}}{\sqrt[n]n}.$$ Because  $a_n ^{1/n} < 1$, certainly the numerator on the left-hand side of the equation above is $<1$. And because $n$ tends to $\infty$, and $n > 1 \rightarrow \sqrt[n]n > 1,$ the denominator is $>1$. Therefore the limit is $<1$ and the root test implies that $\sum \frac{\sqrt{a_n}}{n}$ converges.     If there are any errors in my proof, I think they come from 1) my assumption of the converse of the root test theorem and 2) my misunderstanding of $\lim_{n\to\infty} sup$. Thanks in advance for your help.


We could have written = as "equals", + as "plus", $\exists$ as "thereExists" and so on. Supplemented with some brackets everything would be just as precise.   $$\exists x,y,z,n \in \mathbb{N}: n>2 \land x^n+y^n=z^n$$  could equally be written as:  ThereExists x,y,z,n from theNaturalNumbers suchThat       n isGreaterThan 2 and x toThePower n plus y toThePower n equals z toThePower n   What is the reason that we write these words as symbols (almost like a Chinese word system?)  Is it for brevity? Clarity? Can our visual system process it better?   Because not only do we have to learn the symbols, in order to understand it we have to say the real meaning in our heads.  If algebra and logic had been invented in Japan or China, might the symbols actually have just been the words themselves?  It almost seems like for each symbol there should be an equivalent word-phrase that it corresponds to that is accepted.


I have created a custom exit button and i want the code to terminate if that button is pressed. How can i achieve that?  String[] button1 = {"exit", "next"}; //if next is pressed if (code == JOptionPane.YES_OPTION) {   JOptionPane.showMessageDialog(               null,                "Knock knock" + "\nWho is there",               "The Jasmin Project",               JOptionPane.YES_NO_OPTION);   int no = JOptionPane.showOptionDialog(null, "Want to view more?",               "The Jasmin Project",               JOptionPane.YES_NO_OPTION,               JOptionPane.INFORMATION_MESSAGE,               null,               button1,               button1[0]);   //end code if exit is pressed               if (no == JOptionPane.NO_OPTION) {      System.exit(1);   } }


how to install tp link wn725n wifi usb adapter on ubuntu Ubuntu 14.04.3 LTS

i have a usb wifi adapter Tp-Link model: wn725n  it works very well on windows but i can't find any drivers for linux/ubuntu i tried everything online but nothing work so far  i'm using   Ubuntu 14.04.3 LTS  3.19.0-28-generic  laptop: hp probook 4540s  can you please help me install this adapter?


Error when trying to get a bundle from another activity

I'm trying to retrieve a bundle from another activity but when I try this, the following error appears in my logs: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.os.Bundle.getInt(java.lang.String)' on a null object reference  The part of the code where I try to retrieve and show the bundle is this:  Bundle bundlefrankrijk = getIntent().getExtras();     int scorefrankrijk = bundlefrankrijk.getInt("finalScoreFrankrijk");      TextView highscoreLabelfranrkijk = (TextView) findViewById(R.id.highscorefrankrijk);      SharedPreferences settingsfrankrijk = getSharedPreferences("GAME_DATA", Context.MODE_PRIVATE);     int highScorefrankrijk = settingsfrankrijk.getInt("HIGH_SCORE", 0);      if (scorefrankrijk > highScorefrankrijk) {         highscoreLabelfranrkijk.setText("High Score : " + scorefrankrijk);          SharedPreferences.Editor editor = settingsfrankrijk.edit();         editor.putInt("HIGH_SCORE", scorefrankrijk);         editor.commit();     } else {         highscoreLabelfranrkijk.setText("High Score : " + highScorefrankrijk);     }   This is how I'm sending the intent to the current activity:  Intent i = new Intent(QuizActivityFrankrijk.this,  QuizResultaatFrankrijk.class);             Bundle bundlefrankrijk = new Bundle(0);             bundlefrankrijk.putInt("finalScoreFrankrijk", mScoreFrankrijk);             i.putExtras(bundlefrankrijk);             QuizActivityFrankrijk.this.finish();             startActivity(i);   Thanks in advance!


How to deal with a user who gives out consistently bad advice?

There's a user who frequents the same tag as I do on Stack Overflow, and I consistently see him giving either bad advice, or advice that's not relevant to the question or just says "no you're doing it all wrong, do this instead" where the this is not best practice. It's not the worst, but it's far from good.  Unfortunately the tag I frequent doesn't get much voting traffic (and generally has a lot of new users, some of whom don't know the difference between a good answer and this person's answers and some of whom don't vote or mark answered) so I can't just post a competing answer and expect the community to magically solve the issue of the other user's answer quality. Plus I don't always have time to write a better/more-detailed answer, and sometimes I don't have enough confidence in my domain knowledge to propose an answer (though I know that this other user is at least somewhat wrong/bad).  My question is - what do I do in this situation? Once or twice I've voted this user's answers down when they've been particularly bad. Earlier today I commented on one of his answers saying that it didn't really answer the question asked (as well as posting my own answer giving a really detailed discussion of what can be done) and got a snarky "well I could give all the details like you did but then he's not learning" response back (I admit maybe I went over the top and gave an almost copy-and-pastable answer, but this guy's answer was completely rubbish and did not answer the question).  There doesn't seem to be a way to flag a user for an in-depth moderator overview, and I'd rather not waste the smallish rep I have (600ish) downvoting 90% of this person's answers.  I'm really new to SO myself (only because particularly active a couple of weeks ago) so I don't know the conventions or whether I'm caring too much. Any advice would be appreciated. I can give concrete details on request (examples and explanations of the user's bad answers, the snarky comment to me (which I flagged as non-constructive, by the way)) but thought I'd ask in the abstract first.  FYI the user is not a troll, but I feel that they think they know more than they do. They're probably trying to be helpful like most of us here, but the majority of their answers are just plain bad/confusing. They probably don't even realise it. However, it appears that they take criticism badly, and I certainly don't want to go around commenting on all the answer I find bad explaining why, especially when I have lower rep than they do.  Slightly related:


Is there an example of (2+2)-dimensional flat spacetime with neutral signature (i.e. (+,+,-,-))?  ...for example the metric $ds^2=(dt_1)^2+(dt_2)^2-(dx)^2-(dy)^2$,  has been studied? Are there any papers in this regard in the literature (i.e. I mean where the authors consider also the flat case)  EDITED  QUESTION


Is there a Windows tool for desktop divider (treating one display as two smaller displays)

I use two large LCD displays. I would like to treat one of the displays as two smaller displays.   It would be the opposite of merging two displays to become one continuous desktop space.  For example, when I move one application to one of the smaller virtual display areas and click "Maximize", it would maximize to the size of that virtual display, not to the size of the LCD monitor.


i have done to install and config the postfix but when i test to telnet   i get the result  Trying ::1... telnet: connect to address ::1: Connection refused Trying 127.0.0.1... telnet: connect to address 127.0.0.1: Connection refused   i have try to use more way for solved the problem but can't find the solution.  the   master.cf  smtp      inet  n       -       n       -       -       smtpd #submission inet n       -       n       -       -       smtpd #  -o smtpd_tls_security_level=encrypt #  -o smtpd_sasl_auth_enable=yes #  -o smtpd_client_restrictions=permit_sasl_authenticated,reject #  -o milter_macro_daemon_name=ORIGINATING smtps     inet  n       -       n       -       -       smtpd #-o smtpd_sasl_auth_enable=yes #-o smtpd_reject_unlisted_sender=yes #-o smtpd_recipient_restrictions=permit_sasl_authenticated,reject #-o broken_sasl_auth_clients=yes #  -o smtpd_tls_wrappermode=yes #  -o smtpd_sasl_auth_enable=yes #  -o smtpd_client_restrictions=permit_sasl_authenticated,reject #  -o milter_macro_daemon_name=ORIGINATING #628      inet  n       -       n       -       -       qmqpd pickup    fifo  n       -       n       60      1       pickup cleanup   unix  n       -       n       -       0       cleanup qmgr      fifo  n       -       n       300     1       qmgr #qmgr     fifo  n       -       n       300     1       oqmgr tlsmgr    unix  -       -       n       1000?   1       tlsmgr rewrite   unix  -       -       n       -       -       trivial-rewrite bounce    unix  -       -       n       -       0       bounce defer     unix  -       -       n       -       0       bounce trace     unix  -       -       n       -       0       bounce verify    unix  -       -       n       -       1       verify flush     unix  n       -       n       1000?   0       flush proxymap  unix  -       -       n       -       -       proxymap proxywrite unix -       -       n       -       1       proxymap smtp      unix  -       -       n       -       -       smtp # When relaying mail as backup MX, disable fallback_relay to avoid MX loops relay     unix  -       -       n       -       -       smtp         -o smtp_fallback_relay=   thank you


The usage of "and" & "or" in negative sentences

Is is grammatically okay to say?  I can't do this and that   My colleague persists that when you negate the verb, you can't use 'and' and it should be either;   I can't do this or that   or  I can neither do this nor that   This doesn't sound substantial to me. I've tried googling, but there weren't any thread that specifically discusses this. Either it's pretty much rudimentary and usage of 'and' is completely okay, or I'm going to learn something new.  Please share some insights.


proof of weak convergence of probablity measure

Let $(\mu_n)_{n\in\Bbb{N}}$ be a sequence of probability measure on $\Bbb{R}$ with characteristic functions $(\phi_n)_{n\in\Bbb{N}}$. Assume that $\lim_{n\rightarrow\infty}\phi_n(t)=1$ for all $t\in[-\delta,\delta]$ for some $\delta>0.$ Prove that $\mu_n$ converges weakly to $\delta_0$, and hence $\phi_n$ converges uniformly to 1 on any bounded interval.  My thought: I try to prove the property of tightness of $(\mu_n)$. Then if subsequence of $(\mu_n)$ can be proved to weakly converge to $\delta_0$. By the uniqueness, we are done.


Notify us when one of our posts is edited

Your summary page shows "N Edits to your posts" for the selected time period but you really have to be looking for it.  Could we add edits to the notification feed? You could put the reason for the edit (entered--or not--when the editor changes it) and just a link to the post.


Show that $2 ^ n - 1$ divides $3 ^ n -1$ if and only if $n = 1$

My idea was: If $n$ is even,  $\gcd (3ⁿ-1; 2ⁿ-1) =  \gcd (6ⁿ-3ⁿ + 3ⁿ-1; 2ⁿ-1) =  \gcd (6ⁿ-1; 3ⁿ-1) = 2ⁿ-1 $  So $3ⁿ-1 = 2ⁿ-1$ So $3ⁿ = 2ⁿ$, what does $n = 0$ (nonsense pq gets 0/0)  $3ⁿ-1 \equiv 0 \mod 2ⁿ-1$, so $3ⁿ \equiv 1 \mod 2ⁿ-1$, i.e. $3 \equiv 1 \mod 2ⁿ-1$,  $2 \equiv 0 \mod 2ⁿ-1$.  Someone help me?


Hide all references to Science Fiction and Games

On the the right hand side of stackoverflow.com I see "Hot Network Questions" column.  I would like to eliminate any Science Fiction or Game related question from that column and anywhere else I might see them while browsing stackoverflow.com.  I would like to take this action once and not have to maintain a list or words.  I am okay with seeing topics about programming games, but I am willing to not see topics about programming games if I can eliminate seeing anything about games.  I am also okay with just turning off that entire "Hot Network Questions" column if that is the only place where I am likely to stumble on Science Fiction and Game related questions.  I am not anti-science fiction or anti-game, it is just confusing because some of the questions sound real and are intriguing, then I read the question to find out it is some game.  I don't feel compelled to memorize all the icons so I can tell which ones to ignore.


Prove that $g$ is a submanifold: $g (t,u,v) = (t^2,u^2,v^2,\sqrt{2}uv, \sqrt{2}tv,\sqrt{2}tu)$

We consider $g : (t,u,v)\in \mathbb{R}^3 \mapsto (t^2,u^2,v^2,\sqrt{2}uv, \sqrt{2}tv,\sqrt{2}tu)\in\mathbb{R}^6$. I have to prove that $g(\mathbb{S}^2)$ is a submanifold of $\mathbb{R}^6$.  $dg_{(t,u,v)}=\begin{pmatrix}2t&0&0\\  0&2u&0\\  0&0&2v\\  0&\sqrt{2}v&\sqrt{2}u\\ \sqrt{2}v&0&\sqrt{2}t\\ \sqrt{2}u&\sqrt{2}t&0\\ \end{pmatrix} $  So it proves that $g$ is an immersion (the rank is $3$ clearly) for $(\mathbb{R}^3-\{(0,0,0)\})$.  Now how to prove that $\mathbb{S}^2$ is homeomorphic to $g(\mathbb{S}^2)$ ? I must prove that $g$ is injective  ?  Thanks in advance !


libraries with template function linking error

Reading the following  I solved my problem, however my template function is actually being called, within the library so it is being implementation I would have thought this should have defined its type in the shared objects, however I keep getting linker errors. Consider...  I have the following files (common.h, common.cpp, myclass.h and myclass.cpp) defined below:  common.h  namespace myn {     template<class T> T map(T val1, T val2); };   common.cpp  #include "common.h" template<class T> T myn::map(T val1, T val2) {     return val1+val2; }   myclass.h  #include "common.h" class myclass { private:     int val; public:     myclass(int v1, int v2); };   myclass.cpp  #include "myclass.h" myclass::myclass(int v1, int v2) {     this->val = myn::map<int>(v1, v2); }   I compile the library using:  g++ -Wall -fPIC -c common.cpp -o common.o g++ -Wall -fPIC -c myclass.cpp -o myclass.o g++ -shared -Wl,-soname,libmylib.so -o libmylib.so common.o myclass.o   When given main.cpp:  #include "common.h" #include "myclass.h"  int main(int argc, char ** argv) {     myclass * x = 0;      if (argc == 1)         x = new myclass(20, 40);     else         x = new myclass(2343, 435);      delete x;     return 0; }   I compile using:  g++ -Wall -L. main.cpp -o main.out -lmylib   I get the following error:  ./libmylib.so: undefined reference to `int myn::map<int>(int, int)' collect2: error: ld returned 1 exit status   Shouldn't the <int> version of the map function be defined? I know that if i try doing something like myn::map<char>('a', 'b'); It should complain as it has not been defined, but surely in my case <int> template is defined.


How to design a 5-32 decoder using 4-16 decoder with enable?

I am finding it hard to find a detailed step by step process. Do I have to make a truth table?  Workings so far: I can guess that I would need 2 4-16 decoders, which share the 5 inputs of the required 5-32 decoder, and gives 32 outputs. But that leaves me with 1 extra input that I can't cater to, where is it going to come from?


Prove the following inequality.   $\frac1{\sqrt1+\sqrt3}+\frac1{\sqrt5+\sqrt7}+...+\frac1{\sqrt{9997}+\sqrt{9999}}>24$   I tried to rationalizing the denominator and I got the following inequality to be proved,  $$-\sqrt1+\sqrt3-\sqrt5+\sqrt7-...-\sqrt{9997}+\sqrt{9999}>48$$  Once I got that, I don't know what to do with the LHS. Hints or solution would be appreciated.


Put your shoes on and Take your coat off

I have often heard the following statements when someone talks about shoes, cloths, etc. I don't know which one is more appropriate or grammatically correct.   Hey, put your shoes on.  Hey, put on your shoes.  Take off your coat, please.  Take your coat off, please.    Any thoughts? Can we also say "take out your coat"?


How can one get the current error mode. e.g., is batchmode, scrollmode, etc set? I would like to save and restore these modes in lua or be able to have a macro save the current state that can be called later to restore it.  e.g., \savemode and \restoremode


How to remove play in cantilever pivot point?

I have been working my way through issues with noisy front cantilever brakes. After running through many different ways to solve the issue including new pads (Kool Stop Dura2 Duel Compound), setting the toe in and cleaning the rims.  I now believe the noise is being generated by the play in the pivot point of the cantilever arm. It is not possible to tighten the bolt any further so there will need to be a washer or shim placed in here.   Has anyone had any success in removing the play from the pivot point?  The bike is a cyclocross Kona Jake 2012.


Make the sections of your flag history into links and notify users of declined flags

I have the following flag history statistics:    I suggest making each of the entries into links so that the user can easily sort the flags shown. For example, if I wanted to know which of my moderator attention flags were declined, I just click on the respective link and only those entries will be displayed. As it is now, I would have to scroll through 212 flags to try to find the declined ones - something that many users will not do. Allowing users to quickly sort through their flags will give them a better picture of what they are doing wrong (and right) to prevent incorrectly flagging things in the future.  Also, it may not be a bad idea to notify the user whenever one of their flags was declined/disputed for the same reason. Many users won't check their flag history and won't notice when one of their flags was declined and may continue to incorrectly flag in the future.


When I type $\varprojlim_n$ in the common inline math environment I get the picture as below.     However I want to be rendered as .  The same thing happens with summations. I understand that if I use the paragraph math mode it will solve my problem. Unfortunately, that is not an option. Is there any way to do this?


When apple replaces the battery in a 15" MBP retina, do they replace the entire top portion of the case?

Apple's site says it is $199 to replace the battery.   Do the techs replace the entire top portion of the case including  the keyboard and trackpad?   I've read a few things on the internet alluding to that since the battery is glued in, they replace the entire assembly.     Just wondering if this includes the keyboard and track pad.   (I think it must include the keyboard since it is riveted in).  I'm wondering specifically about the trackpad, since mine has been flaky for a while, and now battery is about due for replacement.   Mine is a mid 2012 macbook pro retina.  Update:  Had this done, and for the low price of $199 I got a new keyboard, trackpad and topcase as part of the deal, as expected.   I can't believe how worn out my old keyboard was!


How can I see flags I cast from all sites?

This morning I flagged something on one of the sites where I have fairly low rep. Now I can't remember which site it was. I've checked my flag history on about half of them, even editing the URL for the site where I have no helpful flags, and I can't find this flag. I've been to my network profile and looked at the Activity tab, but it only shows public things like asking, answering, commenting, editing, and reviewing.  Is there a way to see my flagging history across sites? Can we have such a feature, if it's not possible?


How do I get my C# program to sleep for 50 msec?

How do I get my C# program to sleep for 50 milliseconds?  This might seem an easy question, but I'm having a temporary brain failure moment!


Many nouns that end in ‑f are made plural by changing the ‑f to ‑v‑ and adding ‑es.  +----------+-----------+ | Singular |   Plural  | +----------+-----------+ |  half    |  halves   | |  leaf    |  leaves   | |  shelf   |  shelves  | +----------+-----------+     But some nouns that end in ‑f are made plural simply by adding ‑s.  +----------+-----------+ | Singular |   Plural  | +----------+-----------+ |  chief   |  chiefs   | |  roof    |  roofs    | |  cliff   |  cliffs   | +----------+-----------+   Some nouns that end in ‑f can be made plural in two ways, either by adding ‑s or ‑ves:   +----------+--------------------+ | Singular |      Plural        | +----------+--------------------+ |  scarf   |  scarfs or scarves | |  hoof    |  hoofs or hooves   | |  dwarf   |  dwarfs or dwarves | |  wharf   |  wharfs or wharves | +----------+--------------------+   Now my question is how to determine whether to use only ‑s or to change the ‑f to ‑v‑ and add ‑es?


I want to know the exact bloodline of aragorn wether being mixed with elves or edain because it is not clear in the books.


An example of a simple module which does not occur in the regular module?

Let $K$ be a field and $A$ be a $K$-algebra.  I know, if $A$ is artinain algebra, then by Krull-Schmidt Theorem  $A$ , as a left regular module, can be written as a direct sum of indecomposable $A$-modules, that is   $A=\oplus_{i=1}^n S_i$ where each $S_i$ is indecomposable $A$-module  Moreover, each $S_i$ contains only one maximal submodule, which is given by $J_i= J(A)S_i$, and every simple $A$-module is isomorphic to some $A/J_i$.  My question is that, can you,  please,  tell me an example of a non simisimple algebra, or a ring, such that it has a simple module which does not occur in the regular module.  By occur I mean it has to be isomorphic to a simple submodule of a regular module


Can I load a .NET assembly at runtime and instantiate a type knowing only the name?

Is it possible to instantiate an object at runtime if I only have the DLL name and the class name, without adding a reference to the assembly in the project? The class implements a interface, so once I instantiate the class, I will then cast it to the interface.  Assembly name:     library.dll    Type name:      Company.Project.Classname     EDIT: I dont have the absolute path of the DLL, so Assembly.LoadFile won't work. The DLL might be in the application root, system32, or even loaded in the GAC.


Is there a way to create a variable outside of a function and change it while inside of the function?

I am trying to access a variable that I made inside of a function on the outside. This is what I did:      def add(a,b):         v = a + b         print(v)      add(5,5)      print(v)   However, it tells me that it is not defined when I try to print it outside of the function. I then proceeded to create the variable outside of the function first, and then change it inside of the function. This is what I did for that:      v = 0     def add(a,b):         v = a + b         print(v)      add(5,5)      print(v)   In this case, it just printed out 0 instead of 10 on the last line. Is there any way to keep the changes to variable while it was inside of the function instead of it staying the same?


Book about two boys who crash into a cave, and an alien life form protects them but wont let them leave?

Trying to find a book I read in highschool in the early-mid 90's, and it may have been part of the highschool reading list (in australia) .I vaguely remember that one or two boys crash into a cave (or something like this) and it is inhabited by an alien life form which creates a paradise for them. Then later it sabotages their effort to return home and won't let them leave.


Java Industry Standard: Arrays/ArrayLists/Linked Lists

My professor told us that Linked Lists are used as an industry standard with Java based programming over Arrays/Array Lists. Is that true, are there any professionals that use one or the other or a mix of them, or is there something else you use?


can anyone please explain how 2.8 modulo 2 is 0.7999999999999998?

I am not a mathematician, and just started programming in javascript and wonders how 2.8 % 2 = 0.7999999999999998.  Note: I know it is remainder operation.  May be I forgot my school mathematics concepts. Can anyone please explain this? Thanks.


Quick-add quoatation marks at the ends of each line in R


Science Fiction Story About Two Kids That Build A Spaceship Pre-1994

Most likely, pre-1990.  This is a story (book for kids) about two kids that build a spaceship. I remember the spaceship being constructed of shiny metal or tin on the exterior of the ship. I also vaguely recall them using a hammer to attach it. It was built from common materials. I believe in a garage.   It wasn't particularly realistic, and the ship should not have been able to fly.  I also remember that they were helped or joined by a alien (I think he was green). He helped them prior to blasting off into space. He might have been a neighbor.   I also vaguely recall colored stones or gems (perhaps I am mixing stories up).