I want to add the random number to put on textview in Dialogfragment that gets from Timer Activity;  i try to change many times  protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_main);     txt_v=(TextView)findViewById(R.id.hello);     txtv_2=(TextView)findViewById(R.id.textV_2);     btn_str=(Button)findViewById(R.id.btn_give_str);      dia=new DiagFragment();      nBtb=(Button)findViewById(R.id.bt);     nBtb.setOnClickListener(new View.OnClickListener() {         @Override         public void onClick(View view) {              dia.show(MainActivity.this.getSupportFragmentManager(), null);         }     });       timer.schedule(task, 1000, 5000);   }  TimerTask task = new TimerTask() {     public void run() {         if (dia!=null){              ((DiagFragment) dia).setData2(String.valueOf((Math.random() * 10)));          }     } };   public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {     View view=inflater.inflate(R.layout.list_dialog,null);     mContext=getActivity();      initView(view);      return view; }   public void initView(View view){     tx1=(TextView)view.findViewById(R.id.tv_1);      tx2=(TextView)view.findViewById(R.id.txv_2);  }    public void setData2(String string) {      str2=string;     Log.w(TAG, "setData2: "+string );     tx2.setText(string);   }  I can get data on diafragment, but I get an error when I add data to the TextVIew (tx2)  the error message is :     java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference         at com.soundgil.dailogonclicklistend.DiagFragment.setData2(DiagFragment.java:68)         at com.soundgil.dailogonclicklistend.MainActivity$2.run(MainActivity.java:54)

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


From what I have gathered, singleton is bad and shouldn't be used frequently.  Is that the case or just singleton gets a bad rap?  When implementing AbstractFactory patterrns, I tend apply singleton to every  class TypeFactory extends AbstractFactory. Lets say ShapeFactory and ColorFactory, there should only be one instance of each factory, thus the use of singleton.  What you guys think? Is the usage in this case justified or bad practice?

The  is a fully paid up member of the 's , but it lately seems rather orphaned by the developer world. I still use quite a lot of singletons, especially for , and while you have to be a bit careful about multithreading issues (like any class actually), I fail to see why they are so awful.  Stack Overflow especially seems to assume that everyone agrees that Singletons are evil. Why?  Please support your answers with "facts, references, or specific expertise"


Suppose I have a table such as this, for logging all web requests made to my website: CREATE TABLE weblog (     id      bigserial,     moment      timestamp with time zone NOT NULL DEFAULT now(),     ua      text, -- user agent     ref     text, -- referer     "IP-addy"   inet NOT NULL,     PRIMARY KEY (id) )  Most people will be sending the same user-agent, such as "MOSAIC 1.0". Many will send the same referer as well. This means that, although the id, moment, and IP-addy columns will differ, a huge amount of records/rows in the table will end up having the same values for "ua" and "ref". This really got me thinking about storage space and efficiency, but having experimented with this for a few weeks now, I've basically come "full circle", back to thinking that this does make sense after all. Allow me to explain. Although seemingly a gigantic waste, storing these repeated values on the disk may be necessary for performance. I'm not sure about it, but it seems like it probably is. When I back up my database, which was my biggest worry rather than it taking a lot of disk space while "live", I apply the maximum compression to pg_dump (level 9), which I assume means that all of those duplicated values will turn into a single string stored, and then just referenced with small bits for each record which contains the same cell value. This seems to be the case because the difference between using level 0 (no compression) and 9 is pretty huge in the file size of the resulting .pg_dump archive (using the oddly named "custom" (binary) format). I didn't originally think about this, but since it applies compression, the backups probably already are as small as they could be, regardless of my table structure. Currently, I have them structured like this: CREATE TABLE weblog (     id          bigserial,     moment          timestamp with time zone NOT NULL DEFAULT now(),     ua          bigint, -- user agent     ref         bigint, -- referer     "IP-addy"       inet NOT NULL,     PRIMARY KEY     (id),     FOREIGN KEY     blabla,     FOREIGN KEY     blabla )  And then I have one table for each of "ua" and "ref", where I just store a unique string value with a bigserial id and then associate it with the ua/ref bigints (they are no longer text). This makes both SELECT and INSERT queries cumbersome and require an extra query for each INSERT where it puts in the new string (if it doesn't already exist in the table). Basically, it's an "ugly" (not very elegant) solution to the user (me). And it makes me wonder if this method saves so much disk space anyway. I have only done this for my biggest tables -- not for ones that I know will remain "reasonable". It's not worth it to do this for every single text column, and it would feel like I'm really fighting PostgreSQL and probably am doing something wrong. What do you all say about this? Have I fundamentally misunderstood something? Does PG just "expand" my table structure back into the original structure internally, in order to boost performance at the expense of "live" disk space taken up by my database? I feel as if I have a bad understanding of just how much (or little) PG actually "abstracts away", and how "clever" I have to be in my structure these days. I may be mentally stuck in the 1970s or something by thinking like this. Maybe I've gained nothing from all this work with extra tables, FKs, and extra/complicated queries?

I have two processes which execute code like this in parallel:  begin; update foos set unread=false where owner_id=123 and unread=true; commit;   This results in deadlocks.  My understanding of what causes deadlocks is like the scenario described in , with "interwoven" UPDATE statements updating two different rows in a different order. I don't understand how a single UPDATE statement could result in a deadlock. I'm not able to replicate the deadlock scenario using two parallel psql sessions in my dev environment. My guesses for why I can't replicate it:   I'm misunderstanding my code which creates the deadlock error, and there are actually multiple UPDATE statements in each transaction The "interwoven" aspect is happening, but "within" the UPDATE statement which covers multiple rows, so it's difficult to replicate.   Is it possible for this single UPDATE to be creating the deadlock?


Has anyone implemented Typeahead in visualforce? If so, were you able to apply any styles to it based on the styleClass attribute? I've been trying to get it to style something like a "mailing city" field in VF page but it doesn't seem to be working. Any thoughts?  <apex:page > <style>  .defaultTextBox { padding: 0; height: 30px; position: relative; left: 0; outline: none; border: 1px solid #cdcdcd; border-color: rgba(0,0,0,.15); background-color: white; font-size: 16px;     }   </style>      <c:Typeahead object="Account" placeholder="type something here..." primaryField="Name"                  searchScope="Name" minSearchLength="3" styleclass="defaultTextBox" />       </apex:page>   I'm trying to use the Visualforce typeahead component. Here's the screenshot of where I'm struggling, . I don't need such a big text box. How do I reduce the size, remove the bordering etc...that's where I'm struggling with.

I am trying to get  to work within salesforce visualforce pages.  I have a basic vf page from  example, but it does not respopnd, I suspect there may be some "unknown" workaround needed? Does anyone know?  <apex:page standardController="Contact" showHeader="false" sidebar="false" docType="html-5.0"  standardStylesheets="false">  <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script> <script src="http://twitter.github.io/typeahead.js/releases/latest/typeahead.bundle.js"></script>      <div id="the-basics">   <input class="typeahead" type="text" placeholder="States of USA"/> </div>  <script>     var substringMatcher = function(strs) {       return function findMatches(q, cb) {         var matches, substrRegex;          // an array that will be populated with substring matches         matches = [];          // regex used to determine if a string contains the substring `q`         substrRegex = new RegExp(q, 'i');          // iterate through the pool of strings and for any string that         // contains the substring `q`, add it to the `matches` array         $.each(strs, function(i, str) {           if (substrRegex.test(str)) {             // the typeahead jQuery plugin expects suggestions to a             // JavaScript object, refer to typeahead docs for more info             matches.push({ value: str });           }         });          cb(matches);       };     };      var states = ['Alabama', 'Alaska', 'Arizona', 'Arkansas', 'California',       'Colorado', 'Connecticut', 'Delaware', 'Florida', 'Georgia', 'Hawaii',       'Idaho', 'Illinois', 'Indiana', 'Iowa', 'Kansas', 'Kentucky', 'Louisiana',       'Maine', 'Maryland', 'Massachusetts', 'Michigan', 'Minnesota',       'Mississippi', 'Missouri', 'Montana', 'Nebraska', 'Nevada', 'New Hampshire',       'New Jersey', 'New Mexico', 'New York', 'North Carolina', 'North Dakota',       'Ohio', 'Oklahoma', 'Oregon', 'Pennsylvania', 'Rhode Island',       'South Carolina', 'South Dakota', 'Tennessee', 'Texas', 'Utah', 'Vermont',       'Virginia', 'Washington', 'West Virginia', 'Wisconsin', 'Wyoming'     ];      $('#the-basics .typeahead').typeahead({       hint: true,       highlight: true,       minLength: 1     },     {       name: 'states',       displayKey: 'value',       source: substringMatcher(states)     }); </script>


I initially added a wildcard subdomain as below on my cpanel account and it works fine (all level of subdomain works):   *.example.com   but when I add following second wildcard subdomain to explicitly install ssl for that:   *.co.uk.example.com   any domain ending with .uk.example.com no longer work (e.g. uk.example.com or test.net.uk.example.com ... etc)  is there anything wrong with dns server bind or is this by design?

Q1: Does a DNS rule for *.domain.com match multi-level domain names? In other words, if I just set *.domain.com in my DNS records, will it match all of:  a.domain.com b.a.domain.com c.b.a.domain.com   as many levels deep as needed, with just that one wildcard DNS specifier?  We have a use case for multi-level DNS and I would like to confirm that we are doing the right thing in setting one wildcard DNS setting for the root domain.  Q2: will this work with round-robin DNS?


I'm trying to build a simple demo in jQuery of creating new elements and being able to delete them. I'm not sure why, but I cannot get this to work in jQuery. I can in JavaScript and have built a working demo here:   It seems that the code that doesn't work is this part:  /* NOT WORKING */     $.each(removes, function(el) {       el.on("click", function(){         let removedId = $(this).parent().attr('data-id');         $(this).parent().remove(); console.log('removed id ' + removedId);         updateElements();       });     });    Codepen URL:   I'm not massively experienced in jQuery and don't know why the above isn't working. It should just iterate through each array item (or .remove class) and add an event listener that, when clicked, removes its parent (row).  Can someone explain what specifically is going wrong here and demonstrate how to fix it? Any best coding practices would be much appreciated. Thanks for any help here.  Here's the complete code in jQuery:    // defaults var id = 1, objects = [], removes = $(".remove"); updateElements();  function createEntry() {   id++;    // create new element, append to #container & create new object   var container = $('#container'),       newEntry = $('
'),       title = 'title text here',       description = 'description text here',       remove = 'remove',       dataId = id,       obj = new Entry(title, description, remove);   newEntry.addClass("entry");   newEntry.html('' + title + '' + description + '' + remove + '');   container.append(newEntry);   newEntry.attr('data-id', id);    updateElements();    // constructor & push into array   function Entry(title, description, remove) {     this.title = title;     this.description = description;     this.remove = remove;     this.id = id;      objects.push(this);   }    // tests   console.log('JSON.stringify(objects[0]): ' + JSON.stringify(objects[0]));   console.log('obj.title: ' + obj.title);   console.log('JSON.stringify(obj): ' + JSON.stringify(obj));   console.log('obj.id: ' + obj.id); }  function updateElements() {   removes = $(".remove");   listenForRemoves();    function listenForRemoves() {          /* NOT WORKING */     $.each(removes, function(el) {       el.on("click", function(){         let removedId = $(this).parent().attr('data-id');         $(this).parent().remove(); console.log('removed id ' + removedId);         updateElements();       });     });       } } button { display: block } .entry {  width: 100%;  display: block;  padding: 10px;  border: 1px solid #f5f5f5; } span {   display: block;   width: 100%; } section { background: lightgreen }  <button id='btn' onclick='createEntry()'>Create</button>

   title text here   description text here   remove

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


I want to execute a command in which within a certain radius, players will always be in adventure mode, once outside of that radius, they will be in survival. The command I am trying to use is /gamemode a @a [rm=100] Gamemode S but it's not working quite right.  How do I do this? I do not have much experience with command blocks, all help is appreciated!   Edit: The link provided does not work with a command block, anything else?  I should have noted earlier that I am attempting this on console, sorry for not establishing that earlier!

I think there is a way to do an inside radius, and an outside radius, but how? I want to have a spawnpoint, where @a[r=30] is in gamemode a, and everyone outside is gamemode s. How would I write this?


In Rogue One, towards the end the imperials...      ...decide to fire the Deathstar on the base on Scarif. Their motivation seemed to be vengeance to the rebels that were fighting there, as well as protection to make sure they did not extract any vital information.          But when they fire, they miss the base. Instead the Deathstar blast fires through the tower, and hitting the ground some distance (miles?) away.    Were they rushing and accidentally missed, or did they miss on purpose?

During Rogue One, we saw that the Death Star was able to aim and directly target      the city of Jedha.   So why, an the end of the movie, did they not      fire directly at the archive? They hit what seems to be a location far out in the water, next to the island.


I liked to combine two different materials in to one material in nodes, so that  I could create mountain like structures.  I try to use the noise as the base of the mountain structure, and add a different snow like material to the top of the hills where the normal height is high in the noise texture.  How do I combine two different material on top of each other, so that the height decides what material is used?

I have a terrain with two materials going into a Mix Shader, I want the fac input to be the slope of the terrain. Steep parts should be one color, flat part another.


I know this has been asked and answered here but since I don't have enough rep to ask a clarifying question to the person who answered it I am having to post a completely different question.  I am trying to perform zonal stats on a geotiff with 6 bands (RGB and three thermal and NIR bands). Like the post below it only calculates the stats on the first band.     In the screen shot in the above post, it appears that you can select a specific band when you select the "Input value raster", however mine doesn't look like this. I simply get the Raster Datasets rather than the Raster Bands.   So my question is, how do I get the individual bands so I can calculate zonal stats on each band in this way? Is it that I have to somehow export single bands as new rasters - if so how do you go about doing this?

I'm fairly new to ArcGIS and I get into trouble extracting a single band layer from a raster image .img in ArcMap that I want to use after in zonal statistics. So far, all help I found is to do the operation in the other way around and merge bands and some explanation by using the python code. But I would like to use ArcMap interface.  I tried to create a single layer from ArcCatalog and import it to ArcMap but I get a layer and not a raster. I also tried to import my image.img in ArcMap but then I don't find anything to extract only a specific band.


I've got Ubuntu 16.04 running on a Sony VAIO laptop that has been a workhorse for massive computations for mathematical research for years.  I think it's dying, and I need to save all my data.    After many iterations of manually running fsck and tediously confirming YES to all errors (literally thousands), as in  and others, I finally managed to get it to boot properly and it even loaded up the GUI.  Only problem: in a shell I am treated to the reminder that the filesystem is mounted read-only.  I have a functioning external USB drive (confirmed on another computer), but the dying laptop doesn't mount it automatically nor can I find it using fdisk -l.  And even if I could, I can't create a mount point because that requires writing to the drive.   I would like to just rsync my entire home folder (I'd lose some other things like fonts and LaTeX packages installed elsewhere but whatevs.)  What to do?

Windows asks me to reformat every time I plug it into my computer, so I fired up Ubuntu via VirtualBox (selecting the external hard drive in the USB settings for VirtualBox beforehand) to see if I can access it there.  Does anyone have any suggestions for me? I have over 1TB of data on this drive and do not want to lose it. When I plug it into an electrical outlet, the light turns on, and when I plug it into my laptop, I can feel it clicking.


What could be causing (and how to fix) my tempdb files (8 equal size) to have [avg_write_stall_ms] of 7300ms and the next  highest data file is 47ms.   System is Hyper-V fail-over cluster, SQL 2012 Standard, 60GB RAM, 20 vCPU, EqualLogic PS6100 SAN  Here's my results from the Glen Berry tools    I've requested that the tempdb data files be moved to their own drive letter, but am not sure that will help because it would be the same SAN.

We have the user and system data files on the same disk drive.  The ( io_stall_write_ms / ( 1.0 + num_of_writes ) ) is below 2 for the user files but the tempdb files are typically over 400.  I see that on a few servers and I'm curious if there is a reason it takes longer to write to tempdb than a regular database data file.  SELECT DISTINCT UPPER(LEFT(mf.physical_name, 1)) AS Directory, ( io_stall_write_ms / ( 1.0 + num_of_writes ) ) as result,  io_stall_write_ms, num_of_writes,  fs.database_id,  fs.[file_id] FROM sys.dm_io_virtual_file_stats(NULL, NULL) AS fs INNER JOIN sys.master_files AS mf ON fs.database_id = mf.database_id AND fs.[file_id] = mf.[file_id]   Thank you,


I have this drop down menu to change between charts but it is not working on my site but its works on snippet in here idk why is that. Here is my code below: HTML:
Select country/ region:
  <select onchange="switchVis(this.value)">   <option value="SRbHj/4/">Belguim</option>     <option value="BGQvN/4/">Austria</option> </select>       JavaScript : function switchVis(chartId) {     document.querySelector('iframe').src = 'http://datawrapper.dwcdn.net/' + chartId; }  I am getting this error on the console on the browser  : ReferenceError: Can't find variable: switchVis

What is the scope of variables in javascript? Do they have the same scope inside as opposed to outside a function? Or does it even matter? Also, where are the variables stored if they are defined globally?


Let $G=\left<a,b\right>$ be a finite group. What can I say about the order of $G$ with respect to the orders of $a$ and $b$?  Is it true that $|G|\leq |a||b|$, or are there any counterexamples?  What if $\{a,b\}$ forms a minimal generating set for $G$ (i.e. $\left<a\right>$,$\left<b\right>\ne G$)?

Let $G$ be a group and let $a,b$ be two elements of $G$. What can we say about the order of their product $ab$?   says "not much":     There is no general formula relating the order of a product $ab$ to the orders of $a$ and $b$. In fact, it is possible that both $a$ and $b$ have finite order while $ab$ has infinite order, or that both $a$ and $b$ have infinite order while $ab$ has finite order.   On the other hand no examples are provided. $(\mathbb{Z},+), 1$ and $-1$ give an example of elements of infinite order with product of finite order. I can't think of any example of the other kind! So:   What's an example of a group $G$ and two elements $a,b$ both of finite order such that their product has infinite order?     Wikipedia then states:     If $ab = ba$, we can at least say that $\mathrm{ord}(ab)$ divides $\mathrm{lcm}(\mathrm{ord}(a), \mathrm{ord}(b))$   which is easy to prove, but not very effective. So:   What are some similar results about the order of a product, perhaps with some additional hypotheses?


First of all on this forum i found a lot of sollutions that got really close. But i wasn't able to solve my issue completely  I structured my website using category-subcategoriy- posts. Every once in a while a category is added or removed.   I managed to create a template for the category, which automaticly loads links the the available subcategories  For the subcategories i want to create a different template. I managed to do this manually by creating the category-$slug.php But because new categories & sub categories are created all the time, i would like to do this dynamicly  So whenever i create a new subcategory, the subcategory template is automaticly used. Instead of having to create a new category-slug.php every time.  How can i do this? (i guess this is a noobs question)

I would like to have a different template for categories and subcategories The categories template is set in categories.php is it somehow possible to load the subcategories template from subcategories.php or something like that?


Not long ago i posted a question about this and the solution was to add body as parent like this;  $("#registerF,body").on("change", "input,  select", function () {});   The #registerF element was dynamically loaded and adding body to it fixed the issue.  However I am facing the same problem now and adding body is not working.  I am working on a text editor that uses BBcode just like this one on StackOverflow.  Everything is working when I load that page. But when I load it dynamically it is not working and adding body is not working.  Here is the first fonction as an example:  $("#textEdit").on("focus", function () {     var text = document.getElementById('textEdit');     text.onkeyup = text.onkeypress = function () {         preview = this.value;         preview = bbToHtml(preview);         document.getElementById('editorPreview').innerHTML = preview;     } });       I try several thing like:  $("#textEdit, body").on("focus", function () {  $("body > #textEdit").on("focus", function () {   Nothing is working in this case. I wonder why it is not working for this but it work's for my form registerF element.  EDIT  I think that what causes the problem is the this statement.  Most of it is working but this part:  $(document).click('#textEdit,.editBout', function (e) {     //$("#editToolBar,.editBout").click(function (e) { <-------was     alert('clicked');   <------------get triggered even if i dont click     e.preventDefault();     e.stopPropagation();     console.log(this); <-----------------------------return #document     var style = ($(this).attr("data-style"));  <---- So this is not working   So instead of this i passed it the element:   var style = ($('#textEdit,.editBout').attr("data-style"));  <----Work but not dynamiccaly   So its working but still not working if i load in dynamically. the Click is not getting triggered.

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


I have a python object with several attributes and methods.  I want to iterate over object attributes.    class my_python_obj(object):     attr1='a'     attr2='b'     attr3='c'      def method1(self, etc, etc):         #Statements   I want to generate a dictionary containing all of the objects attributes and their current values, but I want to do it in a dynamic way (so if later I add another attribute I don't have to remember to update my function as well).  In php variables can be used as keys, but objects in python are unsuscriptable and if I use the dot notation for this it creates a new attribute with the name of my var, which is not my intent.  Just to make things clearer:  def to_dict(self):     '''this is what I already have'''     d={}     d["attr1"]= self.attr1     d["attr2"]= self.attr2     d["attr3"]= self.attr3     return d   ·  def to_dict(self):     '''this is what I want to do'''     d={}     for v in my_python_obj.attributes:         d[v] = self.v     return d   Update: With attributes I mean only the variables of this object, not the methods.

So what I'm looking for here is something like PHP's  function.  This is so I can debug my scripts by seeing what's the state of the object in question.


I'm trying to add a 'Lessons' post type to populate the wp-query as well as the pre-existing post type 'Modules. Preferably I would like them to be combined into one query showing the most recent 6 posts. I've only been able to get them showing in 2 different queries thus far.    <?php  //Template Name: Last 6 Modules remove_action( 'genesis_loop', 'genesis_do_loop' ); add_action( 'genesis_loop', 'ca_show_last_six_modules' ); function ca_show_last_six_modules(){  $modules = new WP_Query(array(     'post_type'         => 'module',    'orderby'            => 'menu_order',      'order'                 => 'ASC',     'status'            => 'publish',     'posts_per_page'    => 6  )); if ( $modules->have_posts() ) : ?>     <div class="row">            <?php while ( $modules->have_posts() ) : $modules->the_post(); ?>             <?php get_template_part( 'template-parts/modules', 'loop' ); ?>         <?php endwhile; ?>     </div> <?php endif; }  genesis(); ?>

I'm aware there are several other posts that cover similar ground to what I'm about to ask.  I have three custom post types running, in addition to 'posts'. I want to run a loop that pulls all posts categorised under a particular category   <?php           $args = array(     'post_type' => 'testimonial',     'posts_per_page' => 1,     'tax_query' => array(         array (                  'taxonomy' => 'testimonial_category',                 'field' => 'slug',                 'terms' => 'home'     ) ) ); $query = new WP_Query( $args );                 $postcount = 0;             ?>             <?php if ($query->have_posts()) : ?>                 <?php while ($query->have_posts()) : $query->the_post(); ?>                     <?php $postcount++; ?> //loop here <?php wp_reset_query(); ?>      This is the code I have at the moment, not sure how I condense this into pulling in multiply post types from one category.


if all motion is relative to the frame of reference determined by an observer, why would the view that planet earth revolves around the Sun more correct than the view that the Sun revolved around planet Earth and all the other planets revolve around the Sun?  Is there a mathematical proof?

In history we are taught that the Catholic Church was wrong, because the Sun does not move around the Earth, instead the Earth moves around the Sun.  But then in physics we learn that movement is relative, and it depends on the reference point that we choose.  Wouldn't the Sun (and the whole universe) move around the Earth if I place my reference point on Earth?  Was movement considered absolute in physics back then?


He wouldn't eat this morning.   vs      He didn't eat this morning.   Could you explain to me what the difference is?

What is the difference between would not and did not?  For example:     I called my girlfriend but she wouldn't stop.   I called my girlfriend but she didn't stop.


Is it true that monic and epic implies isomorphism in an abelian category?

Let  $f: C \longrightarrow D$ be a morphism in an abelian category $\mathfrak{A}$ with kernel and cokernel both zero. How can I show that it is an isomorphism? I am not able to find it's inverse.   Let $g: C \longrightarrow D$ be a morphism in the abelian category $\mathfrak{A}$. Let $i: K \hookrightarrow C$ be the kernel of $g$. How can I prove that the induced map $\text{coker}\ i \rightarrow D$ is a monic?   I don't want to use Mitchell's embedding theorem.


I am new to using blender and I am working on rendering a scene that uses portal lighting, but I am having some render issues and I don't know why. Is there anything I can try to fix this issue?  Denoising didn't seem to make a difference on the picture cloudiness one way or another. Adding more samples helped a lot, but I still have that issue some.  Here's a link to my blender file   Thanks everyone, the advice was very helpful! For anyone else having this problem, try the advice below and primarily lower the number of your light sources in the scene.

Since the Denoise feature was added to Blender I only use the default setting with it and it really does the work. But sometimes the denoise is noticable on some of my renders. How can I overcome the blurred effect? Denoising for me is a big help because my system is quite aged.


Sometimes I will see something that does not really belong in Launchpad—a readme, for instance—and I'd like to see it to move it. Sure, I can close Launchpad, open the Applications folder, and hunt for it there (perhaps in subfolders), but it seems to me that there ought to be an easier way. Is there? I can't seem to find one. Right-clicking, sadly, seems to do nothing.  I'm not trying to delete items that are in Launchpad from my drive; I just want to see them in the Finder, so that I can move them around or perform other operations on them..

Is there an advantage to delete apps from Launchpad (Hold one app like in iOS) vs from finder?    And why some apps cannot be deleted from Launchpad?


I altered my /etc/profile and now its showing off some errors whenever i startup my system saying that there's some end of file or something like that missing and the session wont be configured properly. It also says that this is a critical error which needs to be fixed. Kindly help me out on this.  I would appreciate if someone could give me the contents of their /etc/profile

I want to revert a file in /etc/ back to its originally-installed form. I have edited the file since it was installed. How can I revert this config file? Apt is smart enough not to overwrite edited config files, so how do I tell it that I want it to do so?  For argument's sake, let's say that I want to revert the file /etc/foo.conf from the package foo.


Do gravitational waves have a certain speed? Is it the speed of light or infinite, or am I misunderstanding what a gravitational wave is? I think it is a ripple in spacetime caused by interactions between objects, but i could be wrong.

A thought experiment: Imagine the Sun is suddenly removed. We wouldn't notice a difference for 8 minutes, because that's how long light takes to get from the Sun's surface to Earth.   However, what about the Sun's gravitational effect? If gravity propagates at the speed of light, for 8 minutes the Earth will continue to follow an orbit around nothing. If however, gravity is due to a distortion of spacetime, this distortion will cease to exist as soon as the mass is removed, thus the Earth will leave through the orbit tangent, so we could observe the Sun's disappearance more quickly.  What is the state of the research around such a thought experiment? Can this be inferred from observation?


var ItemList = {         0:{name:"Cat%27s%20Pajamas",quality:"Unique"},         1:{name:"C.A.P.P.E.R",quality:"Unique"},         2:{name:"Head%20Prize",quality:"Unique"},         3:{name:"Bedouin%20Bandana",quality:"Unique"},         4:{name:"Spine-Chilling%20Skull",quality:"Unique"},         5:{name:"Voodoo%20Juju",quality:"Unique"},         6:{name:"Australium%20Blutsauger",quality:"Strange"},         7:{name:"Australium%20Axtinguisher",quality:"Strange"},         8:{name:"Australium%20SMG",quality:"Strange"},         9:{name:"Australium%20Ambassador",quality:"Strange"},         10:{name:"Australium%20Force-A-Nature",quality:"Strange"},         11:{name:"Australium%20Black%20Box",quality:"Strange"},         12:{name:"Australium%20Frontier%20Justice",quality:"Strange"},         13:{name:"Australium%20Grenade%20Launcher",quality:"Strange"},         14:{name:"Australium%20Knife",quality:"Strange"},         15:{name:"Australium%20Stickybomb%20Launcher",quality:"Strange"},         16:{name:"Dead%20Head",quality:"Unique"},         17:{name:"Australium%20Flame%20Thrower",quality:"Strange"},         18:{name:"Australium%20Tomislav",quality:"Strange"},         19:{name:"Max%27s%20Severed%20Head",quality:"Unique"},         20:{name:"Australium%20Minigun",quality:"Strange"},         21:{name:"Australium%20Sniper%20Rifle",quality:"Strange"},         22:{name:"Australium%20Scattergun",quality:"Strange"},         23:{name:"Australium%20Rocket%20Launcher",quality:"Strange"},         24:{name:"Towering%20Pillar%20of%20Summer%20Shades",quality:"Unique"},         25:{name:"Australium%20Wrench",quality:"Strange"},         26:{name:"Ghastlierest%20Gibus",quality:"Strange"},         27:{name:"Australium%20Medi%20Gun",quality:"Strange"},         28:{name:"Australium%20Eyelander",quality:"Strange"},         29:{name:"Hat%20of%20Undeniable%20Wealth%20And%20Respect",quality:"Unique"}     }  console.log(ItemList.length);  Basically I have this code with a list. What I trying to do is just print the length of that list. When I run in I get an error: Undefined main.js:34. What does that mean, like the list is defined so I don't see the problem. The 34th line is console.log(ItemList.length); any ideas?

What's the fastest way to count the number of keys/properties of an object?  It it possible to do this without iterating over the object?  i.e. without doing  var count = 0; for (k in myobj) if (myobj.hasOwnProperty(k)) count++;   (Firefox did provide a magic __count__ property, but this was removed somewhere around version 4.)


It is a live-action movie. I saw it long ago on TV. It was released before 2010 for sure, and probably earlier. The channel was probably TV2 or RTL klub, which are commercial channels in Hungary in Central Europe. Please note that I saw it long ago, so the details are a bit hazy; however, I remember a few very specific moments:  It was about a magic school with wizards. The main character was a boy who can shapeshift into an eagle or falcon. Once he used his shapeshifting skill to annoy his friend. When this happened a teacher reminded him of a story where a man turned into a bear and couldn't turn back and because of this, his own family had to kill him. (This is probably just an insignificant moment in the movie.)  I also remember that in the end there was a key they had to make, which was a puzzle with three pieces. It probably opened some door, and the last piece of the puzzle was a girls' pendant that was in front of them all along.

I'm trying to remember the name of a movie in which two young men ask a dragon three questions.  I remember that one of the men asks the dragon, "Don't we get three questions?"  The dragon responds, "Yes, but now you have only two remaining."  Or something along those lines. What movie was this from?


there doesn't seem to be a decent way to google this so here's my issue:  .cpp files include .h files. So lets say I have a class defined in range_search.h, and implement it in range_search.cpp. Not if I want to use it from another cpp file I, again, include range_search.h. This seems to be the right etiquette anyway. This way though, I'm not including the .cpp file anywhere, and currently my code is complaining about not finding the functions therein. What am I doing wrong?  Best, and thanks in advance! Alex  EDIT: As per wish:  range_search.h:  #ifndef RANGE_SEARCH_H_ #define RANGE_SEARCH_H_  namespace range_search {  template<class Point> class RangeSearch {  public:     using value_type = Point;      virtual void assign(const std::vector<Point>& points) = 0;   };  }  // namespace range_search #endif  // RANGE_SEARCH_H_   range_search.cpp:  #include "range_search.h"  namespace range_search {      /// Sets the underlying set.     void assign(const std::vector<Point>& points){         //doing stuff     }   }   main.cpp:  #include "range_search.h"  using Point = std::array<double, 2>;  int main(){      //initialize some points     range_search::RangeSearch<Point> r();     r.assign(points);  }   Error is in German unfortunately:  Fehler: Abfrage des Elementes »assign« in »r«, das vom Nicht-Klassentyp »range_search::RangeSearch >()« ist   r.assign(points);  From what I can tell it's due to the fact that main.cpp has no link to range_search.cpp

Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.)


Is it possible to create a logo in  Photoshop and then open the PSD file in Illustrator Al without flattening the layers and then saving it as a PDF and then it is in a vector format?

I know people prefer using CorelDraw or Adobe Illustrator, but I want to know if there is a technique I can follow to use Adobe Photoshop to make vector Images.


I know we can't move at the speed of light, but if we were to travel on a photon how fast would we see other photons going? The speed of light is constant... So do photons see other photons moving at the speed of light?

Quite a few of the questions given on this site mention a photon in vacuum having a rest frame such as it having a zero mass in its rest frame. I find this contradictory since photons must travel at the speed of light in all frames according to special relativity.  Does a photon in vacuum have a rest frame?


#include<stdio.h> #include<sys/wait.h>  int main() { int p1,p2; p1=fork(); if(p1==-1) { printf(“Error”); } else { printf(“Parent is %d, Child is %d n”,getppid(),getpid()); } p2=fork(); printf(“Parent is %d, Child is %d n”,getppid(),getpid());  return 0;     abcd.c: In function ‘main’: abcd.c:7:4: warning: implicit declaration of function ‘fork’ [-Wimplicit-function-declaration]  p1=fork();     ^ abcd.c:10:1: error: stray ‘\342’ in program  printf(“Error”);  ^ abcd.c:10:1: error: stray ‘\200’ in program abcd.c:10:1: error: stray ‘\234’ in program abcd.c:10:1: error: stray ‘\342’ in program abcd.c:10:1: error: stray ‘\200’ in program abcd.c:10:1: error: stray ‘\235’ in program abcd.c:10:11: error: ‘Error’ undeclared (first use in this function)  printf(“Error”);            ^ abcd.c:10:11: note: each undeclared identifier is reported only once for each function it appears in abcd.c:14:1: error: stray ‘\342’ in program  printf(“Parent is %d, Child is %d n”,getppid(),getpid());  ^ abcd.c:14:1: error: stray ‘\200’ in program abcd.c:14:1: error: stray ‘\234’ in program abcd.c:14:11: error: ‘Parent’ undeclared (first use in this function)  printf(“Parent is %d, Child is %d n”,getppid(),getpid());            ^ abcd.c:14:18: error: expected ‘)’ before ‘is’  printf(“Parent is %d, Child is %d n”,getppid(),getpid());                   ^ abcd.c:14:18: error: stray ‘\342’ in program abcd.c:14:18: error: stray ‘\200’ in program abcd.c:14:18: error: stray ‘\235’ in program abcd.c:17:1: error: stray ‘\342’ in program  printf(“Parent is %d, Child is %d n”,getppid(),getpid());  ^ abcd.c:17:1: error: stray ‘\200’ in program abcd.c:17:1: error: stray ‘\234’ in program abcd.c:17:18: error: expected ‘)’ before ‘is’  printf(“Parent is %d, Child is %d n”,getppid(),getpid());                   ^ abcd.c:17:18: error: stray ‘\342’ in program abcd.c:17:18: error: stray ‘\200’ in program abcd.c:17:18: error: stray ‘\235’ in program

I wrote this program:  #include<stdio.h> int main() { printf(“Hello World\n”); return 0; }   I saved it as first.c and tried to compile but receiving this problem I have installed even gcc compiler too.  $ gcc first.c -o first1 first.c: In function ‘main’: first.c:4:1: error: stray ‘\342’ in program first.c:4:1: error: stray ‘\200’ in program first.c:4:1: error: stray ‘\234’ in program first.c:4:11: error: ‘Hello’ undeclared (first use in this function) first.c:4:11: note: each undeclared identifier is reported only once for each function  it appears in first.c:4:17: error: expected ‘)’ before ‘World’ first.c:4:17: error: stray ‘\’ in program first.c:4:17: error: stray ‘\342’ in program first.c:4:17: error: stray ‘\200’ in program first.c:4:17: error: stray ‘\235’ in program   How can I fix this problem?


From definition of $e^T=\sum_{k\geq 0} \frac{T^k}{k!}$, so $e^0=0^0$...  So, why $e^0=I$ for exponential operator?  Any help would be appreciated.

I have to show that the derivative of 'the matrix exponential' $exp: \mathbb{C}^{n\times n}\mapsto\mathbb{C}^{n\times n}$ at the zero matrix $0$ is $id_{C^{n\times n}}$, i.e. $exp(0)=id$. The above map isn't given explicitly, so maybe someone can tell me what it does to a matrix $A$? I think the obvious guess would be $$A\mapsto e^A:=\sum_{k=0}^\infty \frac{A^k}{k!}$$, but I wouldn't know how to find the derivation of such a map since there is no variable.  So far I tried considering $$Ax\mapsto e^Ax:=\sum_{k=0}^\infty \frac{(Ax)^k}{k!}$$ instead, which is a map $\mathbb{C}\rightarrow\mathbb{C}$ I suppose.   As derivative I get $Ax\mapsto Ae^{Ax}$, which gives the identity for $x=0$, but $0$ for $A=0$.  Can somebody tell me what I got wrong, and how it is true that $exp(0)=id$?


I made an article on "nexgrill vs char broil". I used keywords, I optimized, improved my readability, but still, when I search "nexgrill vs char broil", I see only 2 or 3 websites (on the first page of search results) whose article is purely on "Nexgrill vs Char Broil". The following results were all either forum posts or other grill topics.  I even tried searching "nexgrill vs char broil + sitename" but even though results showed my website on the top results, the articles were still not my "Nexgrill vs Char broil" article. Shown articles were other grill related articles, such as "Best xxxx"  I already tried decreasing keyword density, comparing my article to the top search result articles, using the same words they used, such as "compare", "best", "comparison", "2020", etc.  I'm hopeless! What could I do? I'm in big trouble if I don't make a way, someone will be mad. Please help me, and thank you!

This is a general, community wiki  question and answer pair intended to address any questions   concerning the reasons a site or specific site contents do not appear   in search engine results.      If your question was closed as a duplicate of this question and you   feel that the information provided here does not provide a sufficient   answer, please open a discussion on .   My site (or specific pages on my site) is not appearing in search engine results.  Why isn't my content indexed and what can I do about it?


Is taking laundry powder across national borders by plane likely to cause any problems?  I'm not worried so much about airport security, as border protection forces mistaking it for heroin.  I'm travelling to Hong Kong, Mongolia, South Korea, Japan, and China, but not to the USA.

Instead of plain old coffee, I sometimes like to get my daily caffeine ration from other drinks, e.g. fruit juice. For this purpose I have bought some pure caffeine, which takes the form of white powder.  Now I'd like to take some of that on a journey where I go by plane. I don't want to take the big glass jar of caffeine with me, so the best thing I found is a small transparent bag. It looks somewhat like .    Now I assume this must look pretty suspicious, so I was wondering if your average European airport has the means to identify this as something harmless quickly or if I could expect hours of trouble if this bag were be detected.


trigger quotepotential on Quote_Line_Item__c (after insert) {     list<batch__c> b=[select batch_value__c from batch__c  ORDER BY  batch_value__c DESC LIMIT 1];   if(!b.isempty()){       list<Quote_Line_Item__c> quotelineitem=new list<Quote_Line_Item__c>();         for(Quote_Line_Item__c quoteline:trigger.new){                   quoteline.max_batch__c=b.batch_value__c;                   quotelineitem.add(quoteline);              }     } }   : Compile Error: Initial term of field expression must be a concrete SObject: LIST at line 6 column 24

trigger quotepotential on Quote_Line_Item__c (after insert) {     list<batch__c> b=[select batch_value__c                        from batch__c                        order by batch_value__c DESC LIMIT 1];     if(!b.isempty()){         list<Quote_Line_Item__c> quotelineitem=new list<Quote_Line_Item__c>();         for(Quote_Line_Item__c quoteline:trigger.new){             quoteline.max_batch__c=b.batch_value__c;             quotelineitem.add(quoteline);         }     } }   Help me to find out get rid of this error


Friedmann equation relates Hubble constant to Universe age as 1/H0 times mass density correction factor adding a few percent. What would Hubble have observed 7 billion years ago? The same value? if so what is special about the present moment that 1/H0 fits the current age so closely? Or would the earlier Hubble have measured a bigger constant corresponding to the shorter age? If so the Friedmann equation must be wrong.

How does the  change with the age of the universe?  This question was posted recently, and I had almost finished writing an answer when the question was deleted. Since it's a shame to waste the effort here's the answer anyway.  Maybe this can be one of the canonical answers .


I have dual passports, Canadian and Japanese. The last names on the passport are different, one being my Mom’s maiden name and the other my Dad’s.   I booked a flight to Japan from Canada using my Japanese passport which is in my Moms maiden name. I carried both passports but I did not have an opportunity to present my Canadian passport when I left Canada.   When booking the ticket, I entered my Japanese passport number and from what I’ve read on this forum the airline then notifies immigration that I have left the country. But as I never entered Canada using the Japanese passport in the first place does this cause any problems?  How should I book a flight back to Canada?  Any response is greatly appreciated!

I am a citizen of two different countries, and have two passports.  How should I use my passports when traveling?


How to test convergence of series with comparison test in the next examples:  $$ \sum_{n=1}^\infty \ln\left(1+\frac{1}{2^n} \right)  $$  I know that:  (incorrect)  $$ \ln\left(1+\frac{1}{2^n}\right) < 1 + \frac{1}{2^n} $$  Correct:  $$ \ln\left(1+\frac{1}{2^n}\right) \leq \frac{1}{2^n} $$  Therefore (incorrect) $$ \sum_{n=1}^\infty 1+\frac{1}{2^n}\ $$  Therefore:  $$ \sum_{n=1}^\infty \frac{1}{2^n}\ $$  Is divergent, but that doesn't tell me anything because it is larger than the starting series. So how to solve this using comparison test?  Is convergent which implies that starting series is convergent as of rule:  Suppose that $$ 0 \leq  a_n \leq b_n $$ for sufficiently large n, then:  If $\sum_{n=1}^{\infty} a_n$ diverges, then  $\sum_{n=1}^{\infty} b_n$ diverges.  If $\sum_{n=1}^{\infty} b_n$ converges, then $\sum_{n=1}^{\infty} a_n$ converges.

Does $\displaystyle\sum^\infty_{n=1} \ln(\frac {2^n+1}{2^n})=\sum^\infty_{n=1} \ln(1+\frac 1 {2^n})$ converge?   Condensation, root, ratio and limit comparison tests don't help, I don't know what to do... Any hints please?  Note: no integral test.


I had n number of files are there in my ../in/ directory. From those files I want the oldest file to process and send it to the ../complete/ directory. The remaining files are sent to the ../error/ directory. Can anyone help?

I want to make a bash script to delete the older file form a folder. Every time when I run the script will be deleted only one file, the older one. Can you help me with this? Thanks


I want to export all the variables located in a .conf. So I followed this  answer.   setenv.sh  #!/usr/bin/env bash DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"  set -a . "$DIR/settings.conf" set +a   settings.conf  DB_ENV_USER="root" DB_ENV_PASS="avi" DB_ENV_NAME="s2s" TEST_DB_ENV_NAME="testdb"   What I have tried is,  avi:~/project/_backend$ bash local/setenv.sh avi:~/project/_backend$ echo $DB_ENV_USER  avi:~/project/_backend$   So it failed to show $DB_ENV_USER value root.

What's the difference between executing a script like this:  ./test.sh  and executing a script like this:  . test.sh?  I tried a simple, two-line script to see if I could find if there was a difference:  #!/bin/bash ls   But both . test.sh and ./test.sh returned the same information.


I asked a question () and got several answers pretty quickly. I tried them and they didn't work. So I left some comments on the answers looking for clarification, and apparently the posters edited their answers – but I wasn't notified. I forgot I hadn't found the answer to my question and just came back to it today wondering why there wasn't any activity, only to find out that I'd been ignoring it.    Note: I didn't find a question on Meta that addresses my issue, I'm sure it exists, though. So, if it does, kindly let me know.

Seriously, I had not noticed e.g. Jeff's edit  had he not also retagged my question.


I am using a LaTeX template provided by an academic journal on their website:  If you run the code, the template includes a red warning at the top of the document about the use of such template. Any suggestions on how to remove this warning? It seems that it is within the code itself because I don't see this text in the code. I am using this design for my assignment submission that will later turned into a journal submission. Thank you. Here is the original warning:  Authors are encouraged to submit new papers to INFORMS journals by means of a style le template, which includes the journal title. However, use of a template does not certify that the paper has been accepted for publication in the named journal. INFORMS journal templates are for the exclusive purpose of submitting to an INFORMS journal and should not be used to distribute the papers in print or online or to submit the papers to another publication.  The code itself is here: \documentclass[msom,blindrev]{informs3}   \DoubleSpacedXI \usepackage{natbib}  \bibpunct[, ]{(}{)}{,}{a}{}{,}%  \def\bibfont{\small}%  \def\bibsep{\smallskipamount}%  \def\bibhang{24pt}%  \def\newblock{\ }%  \def\BIBand{and}% \TheoremsNumberedThrough   \EquationsNumberedThrough   \begin{document} \ARTICLEAUTHORS{% \AUTHOR{Author1} \AFF{Author1 affiliation, \EMAIL{}, \URL{}} \AUTHOR{Author2} \AFF{Author2 affiliation, \EMAIL{}, \URL{}}  }  \ABSTRACT{ Text of your abstract  }  \KEYWORDS{} \HISTORY{}  \maketitle  Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.  \end{document}  Update: I am not sure that an assumption posted in one of the comments below by cfr holds all the time. I find a plenty of working papers that look like mine but don't have that message. I am attaching screenshots of my paper vs. the other. Although the names of the journals are different, they belong to the same organization and when I try all original codes still have the same red message. My output:  Vs. a paper available online:

Why is there always a red paragraph in all Informs templates?  Can I edit or delete the red paragraph? Or should I submit my manuscript with the red paragraph?  The first line in the tex file is  \documentclass[orsc,nonblindrev]{informs3},   where orsc is the abbreviation of "organization science(a journal of Informs)".


I'm doing a textmining project about a videogame review dataset. I divided de reviews into a positive (reviewgrade > 8) and negative (reviewgrade < 3) and want to draw conclusions based on the frequency of different grading factors mentioned in the text. I now have a dataframe with counts of certain categories mentioned per review.  0    13249 1     1565 2      292 3       65 4       19 5        6 6        4 7        3 8        2 9        1 Name: positive: gameplay, dtype: int64   0    5043 1     348 2      66 3      18 4       8 5       3 Name: negative: gameplay, dtype: int64   For example this are the distributions of the amount of reviews which have a certain amount of mentions of gameplay related words. There are for example 1565 reviews with precisely 1 mention of a word related to the category gameplay. Now I want to use this data to determine if on average gameplay gets mentioned more in negative context than in positive or vice versa. Because the data is not normal distributed, I assumed a t-test is not appropriate, and found online that a Mann–Whitney U test might be suitable.  > wilcox.test(positive$gameplay, negative$gameplay, alternative = "two.sided", conf.int = TRUE)      Wilcoxon rank sum test with continuity correction  data:  positive$gameplay and negative$gameplay W = 43702925, p-value < 2.2e-16 alternative hypothesis: true location shift is not equal to 0 95 percent confidence interval:  2.963844e-05 4.797412e-05 sample estimates: difference in location            4.995671e-05    I do however get a very high W value, which doesn't seem to be correct.  Is this not the appropriate test, or am I interpreting this wrong?


At the end of Prisoners Keller Dover was forced to jump into the dark pit hole below the junked car on gunpoint by Mrs Jones. He was seen finding a red whistle that fell from his daughter using a mobile torch. Was he able to make a phonecall to his wife or Detective Loki or did the last scene mean to give us all hope?  I think it was at least 2 days since Keller had been confined to the hole. It'd be difficult to find him alive. Was Keller rescued?

In the movie Prisoners, Keller Dover (Hugh Jackman) gets caught by Ms. Jones and he gets placed in her dungeon beneath the car in her backyard.   At the end though, when Detective Loki (Jake Gyllenhaal) hears the faint whistling sounded by Keller, does he realise it's him?  The final scene ends when Loki hears the whistling, looks in the vague direction and the credits roll.   Did Loki find and rescue Keller at the end?   It seems like we're supposed to read into it that Keller was saved, but I'm not too sure.


If I'm playing a Sorcerer/Warlock multi-class and I cast eldritch blast with the Repelling Blast invocation and I have Curse of the Sea from Sea Sorcery how far can I push foes away?

I am trying to understand whether the Curse of the Sea feature of the Sea Sorcerer subclass (from ) works with the warlock's Repelling Blast .  The Curse of the Sea feature states, among other things:     Once per turn when you cast a spell, you can trigger the curse if that spell deals cold or lightning damage to the cursed target or forces it to move.   The Repelling Blast invocation states:     When you hit a creature with eldritch blast, you can push the creature up to 10 feet away from you in a straight line.   If I'm going to be multiclassed in Warlock and Sea Sorcerer, can I trigger the curse off of eldritch blast with Repelling Blast, or not?  It sounds to me like Repelling Blast is a power your character has, not an add-on to the spell, so I tend towards "no," but it kind of feels like they should work together.


As a test, I've got this most simple .tex file:  \documentclass{article} \usepackage[backend=biber]{biblatex} \addbibresource{src.bib} \begin{document} Test test test \cite{abc} \printbibliography \end{document}   with src.bib:  @article{abc,       title={abc},       author={def} }    yet the result is :    The text between square brackets is simple the argument I call in \cite and the output logs a warning:     warning empty bibliography    I assume it doesn't work because of the empty bibliography but I've no idea what I'm doing wrong. The .tex file and the .bib file are in the same directory. My editor is TeXstudio.   does also not help and omitting the backend part gives the same result

I've browsed the forums and found a number of posts that have addressed this issue, but none of the solutions seem to work for me. I have the following script that I just copied from the bibtex home page to get familiar with it. Instead of the citation number I get a question mark. I compile using Latex+Bibtex+Latex+Latex+PDFLatex+ViewPDF just as has been previously suggested and the problem persists.   \documentclass[11pt]{article} \usepackage{cite}  \begin{document}  \title{My Article} \author{Nobody Jr.} \date{Today} \maketitle  Blablabla said Nobody ~\cite{Nobody06}.  \bibliography{mybib} \bibliographystyle{plain} \end{document}   My bibliography (Bib.bbl)  @misc{ Nobody06, author = "Nobody Jr", title = "My Article", year = "2006" }    Looking at previous posts one thing that is concerning is that my .bbl looks empty as shown below. Further, I don't have a .blg  \begin{thebibliography}{}  \end{thebibliography}


When Qui-Gon encounters Darth Maul and the Jedi realise he was a Sith, they are amazed, having believed that they had been extinct for a long time.  On the other hand, at the end of Episode I, Yoda says "always two there are, the master and the apprentice", so they knew about the Rule of Two.  How can this be explained?  EDIT (given the answers)  Let's list the things that happened, which apparently the Jedi were aware of:  1) 1000 years ago the Sith were almost wiped out (became "extinct")  2) 1000 years ago, because they were almost extinct, the Sith started existing through a single pair (master and apprentice)  Given these two facts, why are they surprised? Yes, the Sith were extinct for 1000 years as a civilisation, but there are always two !

At the very end of Star Wars Episode I: The Phantom Menace, Mace Windu and Yoda had this conversation:     Mace Windu: There is no doubt. The mysterious warrior was a Sith.   Yoda: Always two there are....no more...no less. A master and an   apprentice.   When did he come to know about the secret ? And, how? Any evidence from ?


Hello everyone I would like to know if my sentence is or is not correct.   "I don't share my hobbies when I speak to someone is not aware of them like a relevant, a wife, and anyone that I'm not familiar with."

I came across this :     Unbelievable as it may seem, many individuals that fought in the   American Revolution were still alive in 1839, the year the world was introduced to photography. (choose the error - the 'answer' is in bold)   It noted that the reason "that fought" is wrong is that 'The relative pronoun “that” may not be used to refer to people (“individuals”) and should be replaced with the relative pronoun “who.”'   I had thought that the word "that" could refer to both people and objects (while which was reserved for objects and who reserved for people). Am I wrong?


Let $R$ be a commutative ring with identity. Show that if there exists a monic polynomial $p(x)\in R[x]$ of degree $\geq 1$ such that the ideal $(p(x))\subset R[x]$ is maximal, then $R$ is a field.  My attempt: I understand that since $(p(x))$ is a maximal ideal, then $R[x]/(p(x))$ is a field. I also understand that $p(x)$ must be irreducible, else if $p(x)=g(x)h(x)$ then the ideal $(p(x))$ could not be maximal as it is contained in $(g(x))$.  Working with this, I want to show that for every element $x\in R$, there exists some $y$ such that $xy=1$. I'm thinking I can use a map from $R$ to $R[x]/(p(x))$ and somehow show that the product $xy$ gets mapped to the identity. I'm not at all sure about this though, is this a good direction?  Any help appreciated!

I don't see how to solve the following problem:     Let $R$ be a commutative and unitary ring. If there exists a monic polynomial $f(x) \in R[x]$ so that $R[x]/(f(x))$ is a field, show that $R$ is a field. What about if $f(x)$ isn't monic?   I don't have a clue about how proving it. I see that if $R$ is a field and $f(x)$ a monic and irreducible polynomial in $R[X]$ then $\frac{R[x]}{(f(x))}$ is a field, but that is not the question!  Thank you in advance for your help


First time asking a questions here, apologies for any mistakes in advance.  I applied for my first ever credit card online and I was approved for it within seconds. But when I checked my credit score I saw that my score had gone down by 16 points.  Is this usual after being approved for credit card. Will the score go up?  These might be very basic questions but it's my first time and don't want to mess up my score.

I'm trying to decide whether or not I should open up a second credit card. The primary reason is to have a backup credit card in case my only (and oldest) card is cancelled/eliminated for any reason. Length of credit history is 15% of your credit score, and I do not want to put all of my eggs in one basket. The second reason is to simply get a credit card with better rewards.  Currently, I pay my credit card off in full every month, and have done this for the past several years. I also have a car loan and a student loan (I'm not sure how these factor into my credit score). My credit score is 760+.  I'm aware that opening a new credit card can temporarily hurt your credit score by being a "hard pull" against your credit score, but what I'm more concerned about is that the second credit card will cut my "average length of credit history" in half. As an example, if my current credit card has been open for 10 years and I open up a brand new card - my "average length of credit history" will plummet from 10 years to 5. Is this a reasonable fear?  Aside from that, is my rationale valid for wanting a second credit card? Or is it safe to ride out one credit card for life?


Here's the sentence:       I know what if, him, his, and will means/mean.

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


I've been working with an artificial neural network in Torch, to solve a binary classification problem. I've had several troubles by using the mini-batch gradient update.  Each element of my dataset can be -1 (false) or +1 (true). I cannot explain why, but my mini-batch execution tests produce sufficient results (Matthews correlation coefficient in the test set around +0.30) if the percentage of negative elements in the training set is 49%. On the contrary, if it is 50% or greater, the neural network will produce only ones as output, and if it's lower than 49%, the neural network will produce only zeros as output. In all the cases I'm using a mini-batch size of 20.  I decided to take a look to the neural network weights, after training. This is the heatmap of the weights of my input layer neurons (82x100) for my 49% case:    And this is the heatmap of the weights of my input layer neurons (82x100) for my 50% case:    As you can see, the first one looks more stable: almost all the values are around 0, and the extremes are very few. On the contrary, the second one looks quite "crazy", with apparently random values always extremes around -1 and +1.  What are these images telling me?  Is there some addition information I can get from these images?  Why does the second image look so polarized towards the extreme values?

I am using feed-forward NN. I understand the concept, but my question is about weights. How can you interpret them, i.e. what do they represent or how can they be undestrood (besied just function coefficients)? I have found something called "space of weights", but I am not quite sure what does it means.


Is there a way to mirror a directory structure and files there contained with rsync,  giving out facade zero length files?   I mean, mirroring dirs (-d flag I think) exactly as they are, while not copying the files and substituting them some sort or symlink(?) or something like an empty file with his name and attr and no size? In short I want to mirror an env entirely while minimizing uninportqnt files size.

I want create empty files with the same name, but in another location.  Is it possible?   find some files use only filenames touch an empty file in another place   Something like this:  find . -type f -name '*.jpg' -exec basename {}.tmp | touch ../emptys/{} \;


I moved on the Ubuntu a few month ago. At the begining I was flyging with this system. However, it becomes running too slow nevertheles there is no additional problem or loading to system. At this point, do you have any solution, or recommendition to get more stable?

What are your tips for improving overall system performance on ubuntu? Inspired by this  I realized that some default settings may be rather conservative on Ubuntu and that it's possible to tweak it with little or no risk if you wish to make it faster.  This is not meant to be application specific (e.g. make firefox load pages faster), but system wide.  Preferably 1 tip per answer, with enough detail for people to implement it.  A couple of mine would be:   Install  (via Software Center or sudo apt-get install preload); Change  value - "which controls the degree to which the kernel prefers to swap when it tries to free memory";   What are yours?  PS: Since this is not intended to have a unique answer but rather, several useful tips, I'm making this community wiki out-of-the-box.


can anyone  help me? I have to show an example of an integrable random variable X such that X^2 is not integrable (it is not specified discrete or continuos case) I know that a r.v. is integrable if and only if its expected value is well-defined  and is said to be square integrable if the expected value of its square exists and it is well-defined. But I have not idea what type of random variable respects as I requested. Thank you in advance

Can anybody give an example of nonnegative random variable assuming integer  values, almost surely, which is integrable but that has infinite second moment?


I have an object like this: let column = ["A", "B", "C", "D"]  validation: {     type: ...     id: ...     // and possible report that could exists or not     reportA: ...     reportB: ...     //other possible reports added }  I have a column of 4 label, and I have to check if in the validation object exists the report created for the column. So I should check if validation.report"column" exists, if it exists I save the value of the report["column"] in the state, also I'll do a call function. How Can I check if column has the corresponding report in the validation object? I have tried something like this:   column.forEach( value => {         if(this.state.validation + `report${value}`){          setState(....)      }    else{     this.getData(value)     }  it always print me as the data exists inside this.state.validation

Which is the right thing to do?  if (myObj['key'] == undefined)   or  if (myObj['key'] == null)   or  if (myObj['key'])


Something strange has been happening on meta.SciFi recently...    But at least twice now, I've voted on the question and on several of the answers, only to have those votes apparently disappear.     since the question and most of the answers were posted by the same person, if you disagree with the idea of changing the name AND don't like many of the suggested new names, you're casting a lot of votes against the OP.  This raises a few questions:   Since this is a meta site, there's no reputation graph, so can you even tell if your votes are being reversed? Since voting on meta doesn't cost points, should serial votes be reversed on a meta site? If this is an artifact of serial vote reversal, how should a poll like this be conducted?  (I'm less interested in this.)

I've downvoted several of the answers on these Meta discussions:       Both questions are typical self evaluations, Stack Exchange runs them on all young Beta sites and as you may have noticed they are essentially polls, a series of example questions from the site that we are supposed to vote on.  Today I noticed that almost all of my votes have disappeared on both evaluations, only an upvote remains in the later one. My votes triggered the serial voting script, something that :      Heh, it appears I just serially downvoted you (I downvoted a lot of the answers here), hopefully the script is smart enough to not reverse my votes. Will check back in 24h, and if it does, I'll rant about it on MSO ;)    My voting behaviour on both evaluations was very simple:   I had the evaluation open in the left monitor, Opened all the example questions in their own tab, in the right monitor, Scanned each question quickly, and voted on the Meta answer (most of my votes were downvotes), Repeat for the next one, and so on...   I didn't spend more than a few seconds on any question, as I'm fairly regular on the site and I've already read all of them while casually browsing the site. In fact, if my memory isn't failing me, I had voted (up/down) and/or commented, and/or voted to close on each of the 20 example questions. I might have spend a minute or two re-reading a couple, but I mostly scanned through them. In any case I think my voting pattern is quite normal, and the script should be somehow tweaked to take serial posts, posted by the same user in quick succession, into consideration, especially on Metas.   Since I had anticipated that the script would kick in, I could have tried to fool it by pausing a bit between votes or trying to look for other Meta posts to vote on, in between voting on the evaluation answers. However I'm a very active voter on Meta Workplace, there aren't many posts I haven't already voted on, and the few that I haven't is probably because I neither agree or disagree with (my opinion on them is simply "meh"). In any case I think my voting behaviour was natural, and although the serial voting script is awesome, this time it caught and reversed a perfectly legitimate behaviour.  Animuson, in , mentions that the script isn't really optimal on Area51 as well:      Yes, please implement this on Area 51 proposals too! Oftentimes a single user would suggest a plethora of "example" questions to their own proposal which are just terrible, yet all of everyone's votes get reversed and the question just sits there at 0. I've noticed several times that my votes have gotten reversed.    I haven't noticed it myself, but it certainly seems plausible, especially early in a proposal's life.  Mysticial found a related discussion, , but it's focused on voting patterns on main sites, where reputation is also a factor. I can understand jumping through hoops to satisfy the script on main sites where, unfortunately, there are a lot of people trying to get some cheap rep or "punish" others with their downvotes, but not on Metas, and especially not on these evaluation posts.   Voting fraud is a problem, and more often than not the script works wonderfully, but in my case it was extremely counterproductive. Critical evaluations are essential for a young Beta site, and their answers typically only get a handful of votes. I wonder how many of these votes have silently gone away...  Fix this please.


I have apt-get 0.7.23.1 on host machine. I do not have root, thus not able to update it, or install other packages.  I want to download .deb packages with it, but neither  apt-get -d bash   (Invalid operation bash)  nor  apt-get -d install bash   (do not have root)  work.  On my home machine with a newer version of apt-get I can  apt-get download bash   and it does exactly what I want it to.  How can I perform the same on the host machine?

I am often interested in the installation triggers (postinst, postrm) or certain parts of packages (like /usr/share and /etc). Currently, I am running the next command to retrieve the source code:  apt-get source [package-name]   The downside is, this file is often much bigger than the binary package and does not reflect the installation tree.  Right now, I am downloading the packages through :      Download the actual file   This takes too long for me and as someone who really likes the shell, I would like to do something like the next (imaginary) command:  apt-get get-deb-file [package-name]   I could not find something like this in the . The most close I found was the --download-only switch, but this puts the package in /var/cache/apt/archives (which requires root permissions) and not in the current directory.


(not duplicated because i'm specifying version of Ubuntu, other questions are about ubuntu without version)  Does ubuntu 18.04LTS require antivirus/malware?  wich is the best option? if yes.  i have Nod32 but i'm not sure if this is the best option, useful or at least required.  Lastest Nod32 (Linux) version is 4, looks like Nod32 does not care Linux.  is there a good, professional option?

I thought that there was no need to scan for viruses either in Ubuntu or any Linux distros until I found virus scanner packages clamtk and klamav in Ubuntu software center yesterday.  This leads to the following questions:   How do viruses differ between Linux and Windows? How do the strategies for protection differ between Linux and Windows? Should a virus scanner package be installed on my system? If so, which would be a better option?


The topic  shows how to successfully change the speed of the pointer. For example, in my case the solution has been xinput set-prop 13 276 0.7. However, the configuration is lost with the restart of the pc. How to make this change permanent?

I successfully followed  to set different sensitivities for my touchpad and my USB mouse. Only problem is, once you unplug and replug the device or shutdown, restart etc., the settings reset.


I'm using the softwareraid (mdraid) RAID1 on 2 Intel SSD DC S3500 and I found there's a fstrim job on cron.weekly. Does it mean Ubuntu supports it?  I could not find any article saying that SSD mdraid and fstrim is supported for RAID1. And this bug on launchpad is confusing:   I tried to run fstrim manually and it works:  sudo fstrim -v / /: somerandomnumber bytes were trimmed   No luck with the fstrim-all as used in the cron.weekly since there's no verbose option to run that command.

I have heard, that  will have  enabled by default. How will this be done? By adding a discards option to the  mount options or by running a cron-job?   Will the default options for Trim be automatically compatible with the  and encryption layers of the standard Ubuntu-system encryption?  It would be great to see some details about this.


What is the point of the body terminal in a MOSFET?  If we assume Vsource=0 and Vdrain>0 then we will have a linearly changing voltage from drain to source. Then if Vgate>0, depending on the difference between Vgate and the voltage on each point in the MOSFET below the gate, we might, or might not, have an inversion channel.   So what is the actual purpose of the body being connected to source? Why don't we simply let it float? I know that if the body voltage is different than the source voltage, the threshold voltage will change, but what if the body terminal is left to float?

I must be overlooking something but I really don't see the need to have a bulk terminal. I am studying the body effect whereby it somehow interferes with the threshold voltage. I don't fully understand it because I'm finding creating the terminal in itself counter intuitive.    I am told that it must be connected to the lowest or highest voltage in a circuit, depending on n or p channel. First of all, if this interferes with the threshold voltage, wouldn't my supply rails directly interfere with the mosfet since they could be 1V or 15V. Not to mention if there was noise in the power supply, it would directly transmit through, no?  What would happen if there was no body terminal?   Why does a BJT not need one?  Do enlighten me.


$a =\prod_{i = 1}^{r} p_{i}^{a_i}$ with $a_{i} > 0$ for each $i$ is the canonical representation of $a$,Prove that $a$ is the square of an integer if and only if $a_i$ is even for each $i$.  -The section we are currently studying involved purely numerical GCD and LCM questions along with some questions involving finding the number of positive divisors and sum of positive divisors. we did not although go over proofs such as this and I am a bit lost as to how to structure it. Any help is really appreciated.

$a =\prod_{i = 1}^{r} p_{i}^{ai}$ with $a_{i} > 0$ for each $i$ is the canonical representation of $a$, deduce a formula for the sum of the squares of the positive divisors of $a$.  -The section we are currently studying involved purely numerical GCD and LCM questions along with some questions involving finding the number of positive divisors and sum of positive divisors. we did not although go over proofs such as this and I am a bit lost as to how to structure it. Any help is really appreciated.


I need to design an edge detection circuit to detect when a square wave signal goes from Low to High (rising edge) and when it goes from High to Low (falling edge). The circuit should preferably use simple logic control such as 74LS series logic. I know people are gonna suggest using an arduino with interrupts but in my application this needs to be done in hardware rather than software.  Edit: The output is expected to be a short digital pulse, used as a trigger.

I am designing a hobby project that will run on a battery so I am trying to reduce power consumption. The SoC I am using has the ability to go into a deep sleep mode where it consumes very little power, and then can be interrupted by a falling edge on a pin.  I want to generate a high-low-high pulse when the state of a reed switch changes in either direction. I have been reading a lot and it seems that a one-shot monostable circuit can be built from a couple of transistors and an RC circuit to generate an output pulse when an edge is detected. I understand how that works. However, I can't figure out the best way to also pulse on the opposite edge.  One thought, was to just combine two one-shots that are configured to trigger on rising and falling edges respectively, and use the transistors at the output to pull the common pull-up low (kind of like a NOR gate).  Since I am a hobbyist, I am mostly using passive components. What is the "real" way of doing this in a low-power configuration using logic devices?  Edit: I figure I should mention something about the timing requirements. Normally the reed switch will be either open or closed for many seconds at minimum before changing states.  Edit: Here is an example of the circuit I was using for detecting only the falling edge:    And here is the ~20ms pulse it was producing for ~200ms button press simulating the reed switch (Channel 1 is Vbe for T1 and Channel 2 is measured at RST):


Recently I have seen the following HTML when viewing source code in Chrome:  <select class="menu_combo" onchange="javascript:myfunction()"> <!-- rest of code goes here -->   Why is the word javascript and a colon (:) added in front of myfunction()? I thought that onchange was a javascript event. If so, what is the need for this?

I've been making a concerted effort to improve my javascript skills lately by reading as much javascript code as I can. In doing this I've sometimes seen the javascript: prefix appended to the front of event handler attributes in HTML element tags. What's the purpose of this prefix? Basically, is there any appreciable difference between:  onchange="javascript: myFunction(this)"   and  onchange="myFunction(this)"   ?


Here's the sentence: "CONAMES's Flight Performance Systems (FPS) product family includes solutions on aircraft that collect, process and convey valuable information used to increase the performance of the pilot and aircraft while increasing overall flight safety."  I'm not sure how I'd go with this.  It just doesn't read well either way.  (Company site 'About' copy.)

I'd say Microsoft have a way of bending the rules and I know that McLaren have won the championship. While this sounds strange, I believe it is correct English (sorry, I'm not native).   But when it's a small company, would you still use it this way? Is a company always plural, or are small companies singular? I.e., would you say Bakery Johnson makes fine bread or Bakery Johnson make fine bread? Is it My book seller, Woody's, have moved or is it has moved?


Can I make it so my external hard drive will only open on my devices. Maybe an app that will restrict access?

Let me give you some backup story first: A computer technician challenged me to give him my laptop and ask him for any piece of information that I wanted to "hide" in my hard drive. He claimed that he would be able to retrieve anything, no matter what I do to hide it.  Since I do not appreciate absolute statements like: "and there is nothing you can do about it", I started thinking about this in my head. I realized that a very secure Operating System would not cut it, since he does not need to boot from this specific hard drive in order to find things in my hard drive.  The generic question here is:  Is there a way to completely secure all data in a hard disk? (I do not need detailed explanation on how to do it, I just need you to point me to a direction; I can read more about it myself)  Specifically, I suspect that I may need:   An Operating System that is very secure and possibly encrypts all the data that it stores (no idea if such thing even exists). If the above does not exist, is there a way to manually encrypt the data in my hard drive and still be able to boot from that hard drive?   In general, I want to make the hard drive as least accessible as possible to anyone that is not me (= knows a specific password/key), so any solutions are welcome.


A fermion is a particle whose spin is an odd multiple of $\frac 1 2$, and a boson is a particle whose spin is an integer. From what I've seen, these appear to be the only two possibilities; not only have no particles been discovered with a spin of, say, $\frac 2 3$, it seems as though that's not even considered to be a possibility (in contrast, as I understand, there could be a spin $\frac 3 2$ particle, but it happens that none have ever been discovered).   Why is this the case? Or am I mistaken? Sorry if this question has been asked before, I couldn't find any like it.

Why is it that unlike other quantum properties such as momentum and velocity, which usually are given through (probabilistic) continuous values, spin has a (probabilistic) discrete spectrum?


Our .htaccess is part of the repo even though it is our .gitignore.  So this is what I did.  git rm --cached .htaccess  That works, but when I do git status it shows the file as staged for commit to be deleted.  If I make this commit, won't it delete it from the repo?  I can unstage it, but then it shows it as modified.  What I need to do is have the file being ignored locally but remain in the repo.  I had to make a small change to the file but don't want the change in the repo.

Can I tell git to ignore files that are modified (deleted) but should not be committed?  The situation is that I have a subdirectory in the repo which contains stuff I'm not interested in at all, so I deleted it to prevent it showing up in auto-completions and the like (in the IDE).  But now, if I add that folder to .gitignore, simply nothing changes, all the stuff is shown as deleted by git status.  Is there a way to make git ignore it either way?  (Alternatively, as I'm using git-svn, could I commit the changes to the local git and ensure they are not passed on to the svn repo?)


I am working on a simple example, if a user clicks on element then all the elements above it should have a class and all elements below it should not have any class applied to them.  Here is my code:

one

two

three

four

   So here if I click on three then the elements for one, two, three should have the class active and element four should not have any class. This is working fine.  Now if I click on one, I am expecting that two, three, four should have any css class but it is not working like that.  Can you please help me where is the issue. I want to use plain Javascript.

How can I change the class of an HTML element in response to an onclick or any other events using JavaScript?


I want to prove that the polynomial $p(x) = x^{4} - 4x^{2} + 8x + 2$ is irreducible over $\mathbb{Q}(\sqrt{-2})$.  Following a series of hints given by my textbook, I start by using the fact that $\mathbb{Z}(\sqrt{-2})$ is a unique factorization domain. So then by a corollary to Gauss' Lemma, I observe that $p(x)$ is irreducible over $\mathbb{Q}(\sqrt{-2})$ iff it is irreducible over $\mathbb{Z}[\sqrt{-2}]$.  Suppose $p(x)$ has a linear factor $x - \alpha$ in $\mathbb{Z}[\sqrt{-2}]$. My hint says that I should be able to infer that $\alpha$ is a divisor of $2$ in $\mathbb{Z}[\sqrt{-2}]$ (this is obvious) and then conclude that $\alpha \in \{\pm 1, \pm 2, \pm \sqrt{-2}\}$. What I don't get is how it even makes sense to consider that $\alpha = \pm \sqrt{-2}$ in the integer field?

Question is :     Prove that the polynomial $p(x)=x^4-4x^2+8x+2$ is irreducible over the quadratic field $F=\mathbb{Q}(\sqrt{-2})$. [Hint : first use the method of proposition $11$ for the U.F.D $\mathbb{Z}[\sqrt{-2}]$(cf.Exercise $8$, Section $8.1$) to show that if $\alpha \in \mathbb{Z}[\sqrt{-2}]$ is a root of $p(x)$ then $\alpha$ is a divisor of $2$ in $\mathbb{Z}[\sqrt{-2}]$ . Conclude that $\alpha$ must be $\pm 1,\pm \sqrt{-2}$ or $\pm 2$ and hence show that $p(x)$ has no linear factor over $F$. Show similarly that $p(x)$ is not the product of quadratics with coefficients in $F$.]   What I have done so far is :  Suppose $\alpha \in\mathbb{Z}[\sqrt{-2}]$ is a root of $p(x)=x^4-4x^2+8x+2$ we would then have :  $p(\alpha)=\alpha^4-4\alpha^2+8\alpha+2=0\Rightarrow 2=\alpha(-\alpha^3+4\alpha-8)$  i.e., $\alpha$ is a divisor of $2$ in $\mathbb{Z}[\sqrt{-2}]$.  so, I have used the method of proposition $11$ for the U.F.D $\mathbb{Z}[\sqrt{-2}]$(cf.Exercise $8$, Section $8.1$) to show that if $\alpha \in \mathbb{Z}[\sqrt{-2}]$ is a root of $p(x)$ then $\alpha$ is a divisor of $2$ in $\mathbb{Z}[\sqrt{-2}]$  I do not understand why does he mentioned that $\mathbb{Z}[\sqrt{-2}]$ is U.F.D and all... I do not use that at all... It is unnecessarily confusing me or i am unnecessarily getting confused.. hint is actually misleading me :(  Now, I have to prove that $\alpha$ must be $\pm 1,\pm \sqrt{-2}$ or $\pm 2$  i.e., suppose I have $2=ab$ in $\mathbb{Z}[\sqrt{-2}]$ then, $N(2)=N(ab)\Rightarrow 4=N(a)N(b)$   i.e.,$N(a)=1\text{ or }2\text{ or } 4$ i.e., $p^2+2q^2=1\text{ or }2\text{ or } 4$ for $a=p+\sqrt{-2}q$   $p^2+2q^2=1\Rightarrow p=\pm 1 \Rightarrow a=\pm 1$ $p^2+2q^2=2\Rightarrow q=\pm 1\Rightarrow a=\pm\sqrt{-2}$  $p^2+2q^2=4\Rightarrow p=\pm 2\Rightarrow a=\pm 2$    Once I prove that those are the only divisors then I would consider :    $p(1)=(1)^4-4(1)^2+8(1)+2\neq 0$ $p(-1)=(-1)^4-4(-1)^2+8(-1)+2\neq 0$ $p(\sqrt{-2})=(\sqrt{-2})^4-4(\sqrt{-2})^2+8(\sqrt{-2})+2\neq 0$ $p(-\sqrt{-2})=(-\sqrt{-2})^4-4(-\sqrt{-2})^2+8(-\sqrt{-2})+2\neq 0$ $p(2)=(2)^4-4(2)^2+8(2)+2\neq 0$ $p(-2)=(-2)^4-4(-2)^2+8(-2)+2\neq 0$   So, no divisor of $2$ is a root..  Thus $p(x)$ do not have a root in $\mathbb{Z}[\sqrt{-2}]$  suppose I have something like :  $$x^4-4x^2+8x+2=(x^2+ax+b)(x^2+cx+d)=x^4+(a+c)x^3+(b+d+ac)x^2+(ad+bc)x+bd$$  But then, $bd=2\Rightarrow \text { b,d  are  a divisors of 2 in $\mathbb{Z}\sqrt{-2}$}$  But then we have seen that only divisors of $2$ in $\mathbb{Z}\sqrt{-2}$ are $\pm 1,\pm \sqrt{-2}$ or $\pm 2$  So, only possibilities are   $x^4-4x^2+8x+2=(x^2+ax\pm 1)(x^2+cx\mp 2)$ $x^4-4x^2+8x+2=(x^2+ax\pm \sqrt{-2})(x^2+cx\mp \sqrt{-2})$   But these are not possible...  This only tells that $p(x)$ is irreducible in $\mathbb{Z}[\sqrt{-2}]$ but then how do i show this is irreducible in $\mathbb{Q}(\sqrt{-2})$ I was expecting gauss lemma to help but it only works for integers and rationals...  So, please help me to clear this..  Thank you...   P.S : Proposition $11$ is Rational root theorem and Exercise $8$ is that ring of integers of $\mathbb{Q}(\sqrt{-2})$ is an Euclidean domain.


How can I make this symbol?    Already searched through , but can't find it.

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


How to write this musician notes with LaTeX?  Please give me some examples and instructions.

I want to write some music symbols in TeX.       How should I write the Bémol, dièse symbols in TeX?


How do I install the aptdcon command to script aptitude package installation?  Someone else had a similar question here:

Simple enough question: is there some shell command (or GUI method) I can use that, given the path to a file on my system, tells me what package put it there? Assuming the file did in fact come from a package, that is.  Bonus question: what if it's a file that isn't installed on my system? Is there, say, a website that will let me look up a file and see what packages, if any, provide it?


Suppose $N=3953$, Alice encryption key is $e_A = 337$ and bobs is $e_B=23$. Eve happens to know the corresponding decryption keys, $d_A=3385$ and $d_B=2663$. Can I use this information to find the prime factorization of $N$?

In the article , the original RSA article, it is mentioned that Miller has shown that n (the modulus) can be factored using any multiple of φ(n).  Imagine I know the public and the private key. But what I really want is the factors of n, the p and q but I cannot use any factorization algorithm in a large number of n.  In the Miller's article it is suppose to say how I can find the two factors, knowing the public and private key. But I cannot understand how exactly it is done. Does someone know? Or have a small example?


How do you get a block to hold NBT data even after being placed and broken? I'm trying to make an adventure map, but a lever with the following code:  {CanPlaceOn:["minecraft:stone"]}   can only be placed once before losing its data and being rendered unable to be placed again. Breaking the lever will give you a generic lever with no modifications. How do I get around this? How can I get a lever with the above NBT tag when it is broken?

In Adventure mode, I'm trying to let a player get blocks that he can place later, is there a way to do it directly or do I have to change them in his inventory?  Situation: The player gets a tool that will allow him to clear a boulder blocking the road. Further down the path, he encounters a broken bridge, and I want him to use the blocks he gathered before to rebuild it.  At the moment, if I build the boulder with blocks having the CanPlaceOn tag, the tag disappear when the player destroys them and they go in its inventory.


does the sequence ${a_n}$ converges implies it is bounded? i think the answer is no, but i've seen a proof used this fact and our TA used this fact in class as the following question:

I don't understand this one part in the proof for convergent sequences are bounded.  Proof: Let $s_n$ be a convergent sequence, and let $\lim s_n = s$. Then taking $\epsilon = 1$ we have: $n > N \implies |s_n - s| < 1$ From the triangle inequality we see that: $ n > N \implies|s_n| - |s| < 1 \iff |s_n| < |s| + 1$. Define $M= \max\{|s|+1, |s_1|, |s_2|, ..., |s_N|\}$. Then we have $|s_n| \leq M$ for all $n \in N$.  I do not understand the defining $M$ part. Why not just take $|s| + 1$ as the bound, since for $n > N \implies |s_n| < |s| + 1$?


I've always been puzzled by the discrepancy between several possible terminological uses for such a basic thing as "linear regression":   A certain number of sources just say it corresponds to the computation of the best linear (or more accurately affine) map between known inputs $x$ in $X = \mathbb{R}^n$ to known outputs $y$ in $Y = \mathbb{R}$. Others consider almost no hypothesis on $X$ itself (it may not even have a "dimension"). They just suppose we are given $(\phi_i)_{i \in I}$ a family of independent scalar fields on $X$ (generally in some regular space like $C^k(X)$ or $L^2(X)$). Linearity only arise because one is looking for the best scalar field in the vector space $\textrm{span}((\phi_i)_{i \in I})$.   One can see that the second definition easily encompasses the first one by choosing $\phi_i(x) = x_i$ for $i \in 1..n$ and $\phi_0(x) = 1$ so this generic definition has always seemed far more natural for me. But I read so often that linear regression can only create linear boundaries on $X$ (which is obviously false if you take the second definition) that I am not sure it is sufficiently widespread to be considered as canonical.  NB: the same issue applies for linear classification as it is just an assignement of a category by comparing a linear regression output with a threshold.

I was reading the following link on non linear regression . My understanding from reading the first section "Nonlinear Regression vs. Linear Regression" was that the equation below is actually a linear regression, is that correct? If so why?  $$y = b_1x^3 + b_2x^2 + b_3x + c$$  Am I also to understand that in non linear regression multicollinearity isn't an issue? I know that multicollinearity can be an issue in linear regression so surely if the model above is in fact a linear regression there would be multicollinearity?


Go to a question that was already edited by someone else Press "edit tags", edit, "Save Tag Edits" => the "edited <date> (<br>) <user>" block in the center under the post still shows the previous editor and date

Today I tried editing the tags using "edit tag" option for 10K users.     Update a tag - > SAVED It didn't showed my name. After a refresh, it showed my name.   Below are the screenshots for clear explanation.    Is this the exact behavior?


I know that in order to understand recursion one must first understand recursion, but how can I build my reputation enough to post or vote or comment or anything when all these things require reputation to begin with?

I'm trying to become more active on stack exchange sites (specifically StackOverflow, but also ServerFault and Meta sites), but I'm having some trouble with it.   I managed to get a small amount of reputation on  as our company started heavily using the product, but I'm having trouble on the more populated sites like SO, where most of my questions are already asked and questions have answers faster than I can give them.  The problem is, I would like to be able to comment and up- or down-vote comments and answers as a way to contribute to the community, but I can't because I can't find questions to ask or answer.  So how should new users get started on stack exchange sites?


Let $(a_n)$ and $(b_n)$ be sequences of real numbers that converges to real numbers $a$ and $b$, respectively. If $a_n\leq b_n$ for all $n\in\mathbb{N}$, then $a\leq b$.  Could I prove this by contradiction and assume $a>b$?   I am unsure how to approach this.

I'm stuck with the proof of the following:  Suppose that $(s_n)$ converges to $s$, $(t_n)$ converges to $t$, and $s_n \leq t_n \: \forall \: n$. Prove that $s \leq t$.   I've tried starting with $s_n \leq t_n \: \forall : n$ and the definitions of each limit (i.e. $|s_n - s| \leq \epsilon \: \forall \: n > N_1$), but I'm not really getting very far. Any help is appreciated!


This is the status of my system:  $ grep 'Swap' /proc/meminfo SwapCached: 0 kB SwapTotal: 0 kB SwapFree: 0 kB   Please let me know how can I increase the swap area without re-installing.

I have, by default, 250MB of swap space in Ubuntu, and I want to expand it to a larger size. I need 800MB, which I think will be enough to open several applications without having to hit the current limit of swap. I hope someone can help me.


I am building a website that will present spatial data (Leaflet) and I plan to include functionalities like: add, move, delete features (i.e. by clicking on the map or on the feature) I would like to use PostGIS as DB. Should I use a GeoServer and if so why? I was planning to store vector data and request them as GeoJSON from DB. The approximate amount of records (10 000 - 100 000).

I was trying  and  I was setting up Tomcat and all.   I suddenly had a question ... why do we need MapServer and GeoServer?   Can these servers pull data from the database layer as the user asks and only presenting what user has asked from the database?