I have been reading quite a lot on the subject in the past hour and I don't seem to be getting an answer, just about amps. I have a 2 watt rated ball valve, and I have a 12v dc 1 amp power supply. W = a * V. So 12 watts power supply? Would it burn out the ball valve?

Power supplies are available in a wide range of voltage and current ratings.  If I have a device that has specific voltage and current ratings, how do those relate to the power ratings I need to specify?  What if I don't know the device's specs, but am replacing a previous power supply with particular ratings?  Is it OK to go lower voltage, or should it always be higher?  What about current?  I don't want a 10 A supply to damage my 1 A device.


For example, a character takes the Magic Initiate feat at level 4, picking spells from the Wizard spell list, because they have been researching and learning all they can about magic (such as a Sorcerer studying their inborn magic or a High Elf expanding on their Cantrip feature). It stands to reason that they would continue their research of magic over their next 16 levels, which indicates that they should learn new spells.  At any point, can the spells chosen through the Magic Initiate feat be swapped out for other spells, according to the same Magic Initiate spell selection rules of two cantrips and one 1st-level spell?

got me thinking about the mechanics of the Magic Initiate feat when you have class levels in the class into which you were inducted.    Among the classes you can pick with this feat are the Bard, Sorcerer, and Warlock, which know a limited number of spells and all have the same statement under Spells Known.     Additionally, when you gain a level in this class, you can choose one of the [class] spells you know and replace it with another spell from the [class] spell list , which must also be of a level for which you have spell slots.   The term "learning" is used both to describe new spells acquired on level-up and the spell acquired through the feat. This would seem to indicate your Magic Initiate spell counts among the spells you know, and is thus eligible for retraining if you learned it as a spell of your class.  An odd change in wording occurs during the Magic Initiate feat description (emphasis mine):     In addition, choose one 1st-level spell from the same list. You learn that spell and can cast it at its lowest level.   This generalization in describing the learned spell's level seems to imply that there exists a scenario where it would not be appropriate to restrict the spell to being cast as a 1st-level spell.  Could one of the charisma casters retrain Magic Initiate into a higher level spell, which they could then cast once per long rest without using a slot?  This would turn an otherwise unexciting feat into, effectively, a Mystic Arcanum for Bards and Sorcerers. This seems too powerful to be intentional,  but the feat description appears to have gone out of its way to permit it.


The real-time data collected helps scientists better understand what’s   happening to rivers and estuaries around the world.   Should it be,      "The real-time data that is collected..."?    What is the rule regarding this?

I stumbled upon a  with the following paragraph:     MBIE has launched an investigation into claims Chinese galvanised   steel coil imports have been dumped on the local market, causing   "material injury" to New Zealand industry, and the case will end up on   the table of newly appointed Commerce Minister Jacqui Dean.   I thought that sentence was grammatically wrong because the author should put the word "that" (as a conjunction) right after the word "claim". I don't see why the author could drop the conjunction. Is this a prevailing phenomenon in American or Australian English?


I was given a cryptography question during an interview the other day and I couldn't come up with a valid answer. Imagine you are given an efficient algorithm which for a given RSA public key (n,e) is able to decrypt 1% of the messages encrypted with that key. 1% means that the algorithm will deterministically decrypt 1% of all possible ciphertexts on the first call, and will never decrypt the other 99% of all possible ciphertexts with any number of invocations. Figure out an algorithm that uses this one and can decrypt any message.   Any ideas ?

I was given a cryptography question during an interview the other day.   Imagine you are given an efficient algorithm which for a given RSA public key (n,e) is able to decrypt 1% of the messages encrypted with that key.   1% means that the algorithm will deterministically decrypt 1% of all possible ciphertexts on the first call, and will never decrypt the other 99% of all possible ciphertexts with any number of invocations.   Figure out an algorithm that uses this one and can decrypt any message. Any ideas?


According to Newton's Universal Law of Gravitation,   $F=G{\frac{Mm}{r^{2}}}$, where   $M$ and $m$ are the masses of the two bodies,   $F$ is the force of attraction between them,   $r$ is the distance between the centers of the 2 masses, and  $G$ is the Universal Gravitation Constant.    However, if the distance between the centers of the 2 bodies is $0$, i.e., their centres of mass coincide with each other, we would have $r = 0$.  Putting this in the formula would give,  $F = G\frac{Mm}{0^2}=G\frac{Mm}{0} = \infty$  Maybe, an example of this can be, when a terrestrial body is taken to the center of the Earth.     How can this be true? And if yes, how can this be practically explained? Isn't gravity supposed to Become $0$ at the earth's core?

Would the effect of gravity on me change if I were to dig a very deep hole and stand in it? If so, how would it change? Am I more likely to be pulled downwards, or pulled towards the edges of the hole? If there would be no change, why not?


Let $^\mathbb{N}\{0,1\}$ be defined as $\{f~|~ f:\mathbb{N}\to\{0,1\}\}$, i.e., all the functions that map $\mathbb{N}$ to the set $\{0,1\}$. We want to show that this set is in bijection with $\mathbb{R}$.   I've been having trouble figuring this out. If we can show there is an injection from $^\mathbb{N}\{0,1\}\to\mathbb{R}$ and an injection $\mathbb{R}\to ~^\mathbb{N}\{0,1\}$, then we can invoke the Schroder-Bernstein theorem to complete the argument that the two sets are in bijection with one another.   We can represent each $f\in~^\mathbb{N}\{0,1\}$ as the dyadic expansion of a real number  $r_j\in[0,2]$, i.e.,  $$ r_j = \sum_{k=0}^\infty \frac{f(k)}{2^k}$$ But $r_j$ may be mapped to by more than one function, so I am unsure as to how to proceed. Any help is appreciated.

I have learnt that the cardinality of the power set of the natural numbers is equal to the cardinality of the real numbers. What is the function that gives the one-to-one correspondence between these two sets?  I have also learnt that there exists no set whose cardinality is strictly between the natural numbers and the real numbers. Is there a proof of this or at least some intuitiveness behind it?


Is there a monadic second-order (MSO) theory, or even formula, T over some signature $\Sigma$, such that for every structure M for $\Sigma$, M satisfies T if and only if M is finite?  (Note that this question is different from a previous question that asked whether there is an MSO theory/formula that is only satisfied by an infinite model. The difference is that the latter formula may be satisfied by some infinite structures but not by other infinite structures of the same signature. Hence, such a formula does not characterize infiniteness. I am asking whether there is a theory/formula that is satisfied by all finite structures of some signature and by no infinite structure of that signature.)

Is there any formula, of monadic second-order logic, that is only satisfied by an infinite set?


Can anyone tell me if it is possible to stop NPCs from tagging along when I am doing their quests in Skyrim?  I have been playing as a stealth character and am finding that the NPCs that want to accompany me on these missions (in particular, the Companions) keep getting in the way, pulling mobs before I'm ready, or bumping me when I am taking a shot causing a miss. They're more a hindrance than a help, so I'm looking for a way to prevent them from coming along?  I understand there is a method to stop followers, but I'm not sure this is the same thing. I'm playing vanilla Skyrim with no addons.  Is there any way to do this?  Edit: I don't believe this is a duplicate. The indicated previous question was about getting a quest follower to stop following on an abandoned or postponed quest. This question is about preventing an NPC or NPCs accompanying the player in a dungeon/quest.  Note the quests I've had the most trouble with NPCs on is the Companions quests, but I'd prefer to not be accompanied on any.

Me and my brony, Aela the huntress, went out and attempted to clear a certain cave near Whiterun, destroying the Silver Hand clan to restore honor to our werewolf kind. I was not prepared for the strength of the final adversary, Kelv the Skinner. After many failed attempts to end him, Aela and I fled the cave. Now, I cannot convince her that the quest is to be temporarily postponed, and she follows me, no matter where I go. Can someone suggest a way to remove her from my party? I have already deselected the quest.  This is the PS3 version of Skyrim. Ergo, I cannot go into the system console or whatever and change anything about the game.


How do I get the headers and footers to reach the top right and bottom right corners of the page? The placement just looks weird now.  \documentclass{article}  \usepackage{fancyhdr}  \pagestyle{fancy}   \lhead{\huge top left header}  \chead{}  \rhead{\huge top right header}  \lfoot{\huge left footer}  \cfoot{\huge center footer}  \rfoot{\huge right footer}  \renewcommand{\headrulewidth}{0.2pt}  \renewcommand{\footrulewidth}{0.2pt} \usepackage[margin=1.8cm]{geometry}  \begin{document}  \huge Will the header and footer appear properly? Will they actually reach the corners of the page? Or will the text be much wider than the header and footer?  \end{document}

How can I make the headings (with fancyhdr) extend to the full width of the text column?  The width of the text is larger than normal because it has been expanded using the geometry package. For this reason the right-aligned headings do not touch the right margin.  Here is a MWE:  \documentclass{article} \usepackage{lipsum} \usepackage{fancyhdr} \pagestyle{fancy}  \usepackage[margin=1in]{geometry}  \begin{document}  \lhead{Left} \chead{Center} \rhead{Right}  \lipsum \lipsum \end{document}


I am wondering which one of the following is correct:   I love building mathematical models. Models are my life. I love building mathematical models. Models is my life.

Which of the following is correct?  How come pumpkin noodles is not a thing?  or  How come pumpkin noodles are not a thing?  I want to post one of the above statements to Twitter with a picture of a bowl of pumpkin noodles i.e. the stuff that comes out of a hollowed out pumpkin.


I am self-learning abstract algebra using Abstract Algebra: An Introductory Course by Gregory Lee. I come across this group: $$U(20)=\{1,3,7,9,11,13,17,19\}$$ I have managed to find two pairs of multiplicative inverses, namely: $$3\cdot 7=1$$ $$13\cdot 17=1$$ I am wondering how to find the multiplicative inverses for $9$, $11$, and $19$. For example, for $19$, the closest I can get is: $$9\cdot 19=11$$ Also, must inverse be unique in a group? In the other words, can two elements have the same inverse? Thank you.

I know the elements in  $\Bbb Z_{16}^\times$ are {1,3,5,7,9,11,13,15}, but I don't know how to find the multiplicative inverses of each element.   The group is supposed to read "Z16 cross"


I have a problem with sending emails via my domain. I have created a homepage with a input field and when you enter a valid email, my domain mail should send an email to the entered mail address.  I'm using phpmailer to do this, but for some reason these mails ending up as junk for outlook and hotmails. (It works fine with Gmail)  Have read alot stack posts about this problem, but haven't solved it yet. Have tried edit the From, Sender, ApplyTo, AddApplyTo and you name it. None seemed to work yet.  Script:  try {     $mail = new PHPMailer(true);      $mail->IsSMTP();     $mail->Host       = "smtp.unoeuro.com";      $mail->From       = "from_mail@domain.com";     $mail->Sender = 'no-reply@domain.com';      $mail->setFrom('from_mail@domain.com', 'Name');     $mail->addReplyTo($_POST['email'], 'Name');      $mail->SMTPAuth   = true;                       $mail->SMTPSecure = "tls";                      $mail->Port       = 25;                        $mail->Username   = "no-reply@domain.com";       $mail->Password   = "password removed";            $mail->Subject    = "Thanks for your interest!";      $mail->IsHTML(true);      $mail->Body='Thanks for your interest';      $address = $_POST['email'];     $mail->AddAddress($address, "Express");      $mail->Send();      }catch (phpmailerException $e) {         echo $e->errorMessage();     } catch (Exception $e) {         echo $e->getMessage(); }   Is there something wrong here in this script that can cause the problem?

This is a tricky one and I've always relied on techniques, such as permission-based emails (i.e. only sending to people you have permission to send to) and not using blatantly spamish terminology.  Of late, some of the emails I send out programmatically have started being shuffled into people's spam folder automatically and I'm wondering what I can do about it.  This is despite the fact that these particular emails are not ones that humans would mark as spam, specifically, they are emails that contain license keys that people have paid good money for, so I don't think they're going to consider them spam  I figure this is a big topic in which I am essentially an ignorant simpleton.


having trouble converting this string into a datetime this is what I tried so far in code:  import datetime  mystring = '2016/5/7/  4:25:00 PM' dateobj = datetime.datetime.strptime(mystring, "%Y-%B-%dT%H:%M:%S-%H:%M") print (dateobj)   it throws me errors and I search in the library and still can't figure it out what I have wrong in my format. Please any help I'll gratly apreciate it

This is my code:  import datetime today = datetime.date.today() print(today)   This prints: 2008-11-22 which is exactly what I want.  But, I have a list I'm appending this to and then suddenly everything goes "wonky". Here is the code:  import datetime mylist = [] today = datetime.date.today() mylist.append(today) print(mylist)   This prints the following:   [datetime.date(2008, 11, 22)]   How can I get just a simple date like 2008-11-22?


Let $R > r > 0$ and $a,b\in B(0,r)\subset R^n$ where $n \geq 2$. Construct a diffeomorphism $f$ of $R^n$ satisfying $f(a)=b, f(x)=x $ for all $||x|| > R$ and $det(Df_x) =1 $ for all $x\in R^n$.  I was trying with $f(x)=\rho(x) g(x) + x$ where $\rho$ is a bump function and $g$ is smooth function with $g(a)=b-a$. But problem is that this type of function may not be diffeomorhism and also jaccobian of $f$ is not necessarily 1.

Let $n>1$ , consider $\mathbb R^n$ with standard volume form $\omega _0 =dx_1 \wedge ...\wedge dx_n$ ; let $r,R$ be two positive real numbers with $R>r$ . Then is it true that for every $a,b \in B(0;r)$ , $\exists$ a diffeomorphism $f:\mathbb R^n \to \mathbb R^n $ such that $f(a)=b ; f(x)=x , \forall x \in \mathbb R^n $ with $||x||>R$ and $f^*\omega _0=\omega _0$ ?   As $f^*(dx_1 \wedge ...\wedge dx_n)=(det f' )(dx_1 \wedge ...\wedge dx_n)$ , so basically given $R>r>0$ and $||a||,||b||<r$ , we have to find a diffeomorphism $f : \mathbb R^n \to \mathbb R^n  $ with $f(a)=b$ ; $f|_{\mathbb R^n \setminus B[0;R]}=Id$ and $det f'(p)=1 , \forall p \in \mathbb R^n $ .  Definitely this cannot work out in $\mathbb R$ , because the only differentiable function satisfying $det f'(p)=1 , \forall p$ and $f(a)=b$ is $f(x)=x+b-a$ and this function never gives identity unless $a =b$


I made a USB with 19.04 following the guide and tried to start it for installation, but I got a kernel panic. I tried an older version and couldn't install it either, but a 14.04 LiveUSB worked OK when I made it earlier.  How do I solve the kernel panic problem with installation?   Processor:    Motherboard:    RAM: 16GiB Dual Channel    Graphics Card:    Yes I did try LTS and also checked the USB - it is completely fine; I can install a VM with the USB but not on my computer.

I am trying to boot Ubuntu on my computer.  When I boot Ubuntu, it boots to a black screen.  How can I fix this? Table of Contents:


So, they say that photographs make you look a little heavier or fatter by 5 to 10 lbs or kgs.    It does appear to be true as most of my photographs make my face look "fuller / rounder" than as it is visible normally or in the mirror.    And for probably the same reason some "skinnier" people look nicer or more attractive.   And for someone who works out and is relatively athletic guy, but never takes any selfies, my selfie skills suck.    And plenty of "short & stout" ladies can pull of better looking profiles.      But I figured there's some photography science & art to this.    I did not know the details behind it but recently chanced upon this article.        Key points of Article:     Camera Lens Distortion (Barrel vs Pin Cushion Distortion) Angles of camera  Your pose     How could I fix these distortions to present a more realistic view of myself?    I'm not trying to look slimmer or all the crazy stuff that people do, just more realistic fix of photographic distortions to reality.    A good detailed "photography science/ technical" response and "How to" would be great.

To take a good self-portrait, I'd look in the mirror, see the expression/angle/light I like, and... fail to capture it.  Any tips on exposure, positioning of the camera (e.g. relative to the eyes), focal length/lens to use.  What it boils down to:   What is the digital (optics, settings) equivalent of an eye? How do you position the camera in such a way, so that the image resembles what you would have seen? (elevation, angle, distance, focal length)   I am not talking about photographing through the mirror. The mirror is only a tool here.


I have a data set that has 8 treatments, along with success data. I used a binomial glm to analyze the data, but generated some unexpected coefficient values for a few of the treatments and not sure what to do about it.  Here is the data and summary:  treatment = as.factor(c("A", "A", "A", "A", "B", "B", "B", "B", "C", "C", "C", "C",  "D", "D", "D", "D", "E", "E", "E", "E", "F", "F", "F", "F", "G",  "G", "G", "G", "H", "H", "H", "H")) rep = c(1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4,  1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4) success = c(1, 1, 1, 2, 14, 17, 15, 18, 0, 0, 0, 0, 18, 18, 17, 18, 4,  4, 2, 4, 2, 4, 1, 1, 1, 0, 0, 1, 8, 6, 6, 2) total = c(20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20,  20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20,  20)  data = data.frame(treatment,rep,success,total) data$perc = data$success/data$total  library(tidyverse) data %>% group_by(treatment) %>% summarize(mean = mean(perc))   We can see that the mean for treatments B and D are .8 and .88 respectively.  Now perform a glm:  model.glm = glm(cbind(success,total) ~ treatment-1,data = data,family="binomial")  logit2prob <- function(logit){   odds <- exp(logit)   prob <- odds / (1 + odds)   return(prob) }  SuccessProb = logit2prob(coef(model.glm)) SuccessProb = round(logit2prob(coef(model.glm)),2) SuccessProb   We can see that the estimates, using a glm, for B and D are .44 and .47, respectively. These are not close to the summary estimates.  If we use an anova, results are better.   model.aov = aov(perc ~ treatment-1,data=data) SuccessProb.aov = coef(model.aov) SuccessProb.aov   Here, the estimates for B and D are .8 and .89. Much better than the glm.  Does anyone know what I am doing wrong here?


I have seen this question over way too many forums and youtube video's etc, however none seem to work. Everyone seems to have an answer but it always seems to be followed by a "haven't tested this myself" style comment or similar.  All I am trying to do is export an FBX with embedded textures to unity. I have tried baking textures with cycles, I have tried the copy path option on the export fbx settings and I have tried clicking: file > external data > pack all into .blend.  None of these options take the textures or create a texture folder in the required designination.  Was hoping exporting to Unity would of been slightly more intuative than this but nevermind.   Any help would be greatly appreciated   (I know this one has been done to death but not sure if something has broken in blender 2.8 update or new versions of unity?)

I exported a .fbx file to Unity 3D, but it retained none of the applied textures.  Is there a way to create a textured model in Blender and export it into Unity while retaining the textures, without having to export my UV layout and retexture it again within Unity?


I have a bunch of files written in mostly one programming language and also some written in others. They are in different folders, but few and targetable.  I want to make a program that says how many lines of code there are. I know I could do this for one file, just like this:  #include <iostream> #include <fstream> using namespace std;  int main() {     ifstream f("file.txt");     int n = 0, aux;     string line;     while (getline(f, line))         n++;     cout << endl << n << " lines read" <<endl;     f.close(); }   But how could I "browse" all the files and folders and read them all? Having to do it explicitly for each one of them sounds awful to me.

How do you iterate through every file/directory recursively in standard C++?


Example 1:  Example 2:    Any other ideas?  association fraternity guild kinship affiliation alliance clan clique community comradeship confederacy coterie fellowship league society union

Is there a gender neutral form for "fraternity/sorority"? How about "brotherhood/sisterhood"?   Example: As in "If mathematicians were to form a fraternity of scholars, as in yet another alpha beta omega club, their hazing rite would be ...".  suggests such organizations are meant to be gender exclusive. So perhaps no words exist to suggest a club of both sexes which otherwise has chracteristics of Greek organizations.


I want to show a progress bar during a bash operation in a specific format something similar to the following:  [###########](40%)   after update it should become   [###############](50%)   and then similarly reach upto 100%  Is there any way to achieve this  I wrote the following bash program but i don't know how to show the percentage in this on same line:  #!/bin/bash {     echo -n "["     for ((i = 0 ; i <= 100 ; i+=6)); do         sleep 0.05         echo -n "###"     done     echo -n "]"     echo }   Let's assume that a certain number of operations are being performed in a loop and after the completion of each operation, I want to report some progress. I don't want to install pv or any other utilities that does not come with default Ubuntu 12.04 installation.

When scripting in bash or any other shell in *NIX, while running a command that will take more than a few seconds, a progress bar is needed.  For example, copying a big file, opening a big tar file.  What ways do you recommend to add progress bars to shell scripts?


I have some text file (for example json). I can use head order for the reading of the first lines. For example:  head -n 100 file.json   get me 100 first lines back. What is Linux order, which I can use to read some general lines somewhere in file? For example from the line 500 to the line 700.

Say I have a huge text file (>2GB) and I just want to cat the lines X to Y (e.g. 57890000 to 57890010).  From what I understand I can do this by piping head into tail or viceversa, i.e.   head -A /path/to/file | tail -B   or alternatively  tail -C /path/to/file | head -D   where A,B,C and D can be computed from the number of lines in the file, X and Y.  But there are two problems with this approach:   You have to compute A,B,C and D. The commands could pipe to each other many more lines than I am interested in reading (e.g. if I am reading just a few lines in the middle of a huge file)   Is there a way to have the shell just work with and output the lines I want? (while providing only X and Y)?


Let $ f: \mathbb N  \to \mathbb N$ be a bijective function such that: $$ \sum_{n=1}^{\infty} \frac{f(n)}{n^2} < +\infty$$ Now my question is does any such $f$ exists?

Let $f:\mathbb{N^*}\to\mathbb{N^*}$ an injective function. Show that the following infinite series $$\sum_{i=1}^{\infty}\frac{f(n)}{n^2}$$ is divergent. I am supposed to deal with this using the rearrangement inequality. But I don't know how!Could some explain this to me step by step? I really want to understand...


The  was deleted by the OP for some unknown reason. I think this was a cute and interesting problem, and I'd really like to know the answer, so I'm just reposting the same question (with a little rewording). Let's consider an initial pair of integers $(a_0,b_0)$ taken in the $\{1,1000\}$ range. Now we iteratively apply one of two simple transformations to such pair, either $$ (a_n,b_n) \to (a_{n+1}=2a_n, b_{n+1}=b_n+1) $$ or $$ (a_n,b_n) \to (a_{n+1}=a_n+1, b_{n+1}=2b_n) $$ Put in simple words, increment one of the elements of the pair, and simultaneously double the other one. Question: does there exist a $(a_0,b_0)$ pair of integers such that there is no path leading to a pair of equal integers?  In a comment of the original question, I expressed the thought that an attack on the problem should probably take the binary representations of the integers into consideration. For instance $$ \array{ 7 \texttt{ 111} \cr 5 \texttt{ 101}  } \to \array{ 14 \texttt{ 1110} \cr 6 \texttt{ 110}  } \to \array{ 28 \texttt{ 11100} \cr 7 \texttt{ 111  }  } \to \array{ 29 \texttt{ 11101} \cr 14 \texttt{ 1110 }  } \to \array{ 58 \texttt{ 111010} \cr 15 \texttt{ 1111 }  } \to \array{ 59 \texttt{ 111011} \cr 30 \texttt{ 11110 }  } \to \array{ 60 \texttt{ 111100} \cr 60 \texttt{ 111100}  } $$ And in another comment, responding to Henry mentioning that he had not yet found a path to equality for $(15,22)$, I responded that there was a path to $123084$, outlining my process to find that path. Essentially, for $$ \begin{array}{rl} 15 &\texttt{1111} \cr 22 &\texttt{10110}  \end{array} $$ to have a chance to reach equality, we have to set to $1$ that second bit of $22$, and we need to do it as soon as possible, which means $8$ additions first to reach $$ \begin{array}{rl} 3840 &\texttt{ 111100000000} \cr 30 &\texttt{ 11110}  \end{array} $$ Now compensating for the length of the binary representation, we get to $$ \begin{array}{rl} 3845 &\texttt{ 111100000101} \cr 960 &\texttt{ 1111000000}  \end{array} $$ and with a final step $$ \begin{array}{rl} 7690 &\texttt{ 1111000001010} \cr 961 &\texttt{ 1111000001}  \end{array} $$ we show that we have transformed the problem from $(15,22)$ to $(10,1)$. And there's a path from $(10,1)$ to $(4,1)$, which resolves as shown above in the $(7,5)$ example (the same sequence of operations that brings $(28,7)$ to equality will work identically on $(4,1)$).

I have a math problem, and I have no idea how to solve it. I first saw it over on the Code Golf StackExchange, . The poster there hinted at knowing that there is a proof, but no proof was provided.   We start with a pair of integers $a$ and $b$. We double one and add one to the other. We have the power to decide which to double and which to increment. We repeat this "doubling/+1" process, until the two integers are equal.  For example, starting with $(2, 5)$ we can double the 5 and increment the 2 to give $(3, 10)$. Then, we can double the three and increment the 10 for $(6, 11)$. We can double the six and increment the 11 for $(12, 12)$ - and now we have made the numbers equal.   Given any pair of integers, it it always possible to make them equal using these steps?  Partial Proof  All pairs of negative numbers will terminate. This relies on the fact that doubling 0 is 0. If we start with a pair of negative numbers, we can repeatedly add one to one of the numbers until it hits 0. While the other number will have been doubled several times, we can repeatedly decrement it until it too, hits 0.   $(-6, -3) \to (-12, -2) \to (-24, -1) \to (-48, 0) \to (-47, 0) \to (-46, 0) \to \cdots \to (0, 0)$


Is it possible to configure a user to login via SSH without password and without using keys. Just typing "ssh user@server". I have tried some modifications with  Match User  and with AllowUsers in /etc/ssh/sshd_config, but with no success. Perhaps I'm not intending on using it on any servers. This is just for testing purposes locally on my virtual machines and to find out if it possible at all.   I have searched for this before posting but could not find the exact same question.

I created an account ckurs on my FreeBSD 10 workstation. This account uses a custom shell-script as a login-shell that attaches the user to a tmux-session in read-only mode. I have sufficiently convinced myself that this is safe.  I would like to give others the ability to login to the user ckurs without providing any form of authentication (no password, no keys, nothing). In the past, I set a simple password for this account but getting users to type that in correctly always caused a little kerfuffle, so I'd like to avoid that.  I started by setting a blank password with pw usermod ckurs -w none. This works for local logins and su but not when I log in via ssh, instead, authentication is refused after prompting for a password three times.  What option do I need to set where in order to allow login without a password? Best would be a configuration that only applied to that one account.  I believe I have not changed any configuration regarding authentication on the system, I believe the system uses PAM to authenticate users by default (I'm not sure though), the PAM configuration hasn't been changed from the defaults delivered by FreeBSD 10.


I know that that duplicate questions automatically post the duplicate to the comments on the question.     Would it be possible / a good idea to have this for all vote closes?  Possibly having a check box at the bottom of the vote close window to post reason as a comment to the question might work as well.   My reasoning for this is I tend to vote close questions for lack of effort.       unclear what you're asking - Please clarify your specific problem or   add additional details to highlight exactly what you need. As it's   currently written, it’s hard to tell exactly what you're asking. See   the How to Ask page for help clarifying this question.   Now in some cases the question could be improved, but a lot of times questions like this are by new users who don't always return.  If I feel it can be improved I like to let these new users know that it was vote closed and why.  I copy that to the comment. example:    Is this something we could consider adding?

If a question gets votes to close but no answer or comment stating the reason for the vote, the OP has no way of knowing if editing would solve the problem.  Show to the asker the reasons (but not who voted) given for a vote to close so they can attempt to correct the problem without having to resort to begging for a reopen or reposting an edited version and risk being called a duplicate.


In the background, there is a process taking up a lot of processing power. Htop says it's using a whole core. (Of my quad core)  It's strange because I have no windows open. How do I identify the greedy process so that I can kill it?

How do I kill all processes running by my own non-root account?  I have some spinning smbd  processes that I caused from my windows machine and so I telnetted into the linux server and I want to kill those spinning processes.   I don't have authority to restart services or reboot the machine.


I'm running CentOS and have a 100GB Micron RealSSD P300. It appears that the drive is almost full, as noted by running df:  Filesystem     1K-blocks     Used Available Use% Mounted on /dev/sda3       94753636 86002428   3937948  96% / tmpfs           12298364        0  12298364   0% /dev/shm /dev/sda1         253871    58571    182193  25% /boot   However, running du / tells another story:  6.9M    /bin 56M     /boot 188K    /dev 28M     /etc 3.3M    /home 251M    /lib 25M     /lib64 16K     /lost+found 4.0K    /media 4.0K    /mnt 8.0K    /opt 0       /proc 11M     /root 18M     /sbin 4.0K    /selinux 0       /service 4.0K    /srv 0       /sys 436K    /tmp 1.4G    /usr 1.9G    /var   What could be taking up all of these blocks that I can't see? Could the drive just be broken? I don't have too much experience working with SSDs, so perhaps there's an obvious step I'm missing?

When I sum up the sizes of my files, I get one figure. If I run du, I get another figure. If I run du on all the files on my partition, it doesn't match what df claims is used. Why are there so many different figures for the total size of my files? Can't computers add?  Speaking of adding: when I add the “Used” and “Available” columns of df, I don't get the total figure. And that total figure is smaller than the size of my partition. And if I add up my partition sizes I don't get my disk size! What gives?


I've been banging my head with the following code...  code = (404, 200)  if code[0] is 404:     print "yes"  if code[1] is 200:     print "yes"   should return true both right? but  just the condition of the number 200 and true why?

My  has failed me.  In Python, are the following two tests for equality equivalent?  n = 5 # Test one. if n == 5:     print 'Yay!'  # Test two. if n is 5:     print 'Yay!'   Does this hold true for objects where you would be comparing instances (a list say)?  Okay, so this kind of answers my question:  L = [] L.append(1) if L == [1]:     print 'Yay!' # Holds true, but...  if L is [1]:     print 'Yay!' # Doesn't.   So == tests value where is tests to see if they are the same object?


I have been testing various Firefox extension for screenshot grabbing, but none of them suited my needs.  Then I have found Shutter (0.86.3), and it is really nice. I use exporting to imageshack and FTP a lot.    The only thing I miss is grabbing the whole web page area (not just the part currently visible on the screen). Is there any Shutter extension for this or similar app with such a feature?

I have used shutter and screenshot applications for a long time for taking screenshots.But they can only take screenshots as big as the physical screen.    Sometimes I have to take an screenshot of an whole webpage,because the page can't be saved properly by the browser or I want to include pop-up's as well.This situation requires a software that can take a screenshot longer than the physical screen.  Is there any software to do this?     Note that  question and it's answers are about webpage saving apps.They won't save pop-up's, which is essential in my case.I don't want a converter.I need an literal screenshot app or anything that could save the pop-up's as well.   And I use Mozilla Firefox, because it has really nice plugins.The solution should be working fot Firefox itself.


I have a virtual Linux server (Kubuntu 14.04) and i will ask the hosting provider for a complete /64-Prefix for this machine (at the moment i have 4 individual IPv6-Addresses).  How do i configure the entire /64-Prefix to a physical interface at my server?I mean, the server must announcing itself to the LAN (inside the hosting provider) as being responsible for the entire /64-Prefix and all other hosts on the LAN (including the border-router with the connection to the real/global Internet) should know that all IP-Packets with a destination-ip-address inside this prefix must be delivered to the MAC-Address of my server.  Example:My hosting provider owns the prefix 2001:db8::/32 for further delegating subnets of it to all its costumers. Then my hosting provider gives me 2001:db8:dead:beef::/64 for my server.How do i configure the Linux on my server that it accept incoming connections on all IP-Addresses inside my /64-Prefix and (even more important) announce itself as the responsible host for all IP-Addresses in the entire Range 2001:db8:dead:beef:0000:0000:0000:0000--2001:db8:dead:beef:FFFF:FFFF:FFFF:FFFF?  All that i have found in the Internet are examples for configuring (multiple) individual/single IPv6-Addresses (each with full 128 significant Bits) for a specific host by appropriate commands in /etc/network/interfaces but i can not find an example for configuring a complete IPv6-Prefix (with below 128 significant Bits) for a specific host.  Second question: What do the host for advertising that he is responsible for a complete IPv6-Prefix and not only for some individual IPv6-Adresses? What type of ICMPv6 Advertisement-Messages are used for this purpose?

I know that the ip tool lets you bind multiple addresses to an interface (eg, ). Right now, though, I'm trying to build something on top of IPv6, and it would be really useful to have an entire block of addresses (say, a /64) available, so that programs could pick any address from the range and bind to that. Needless to say, attaching every IP from this range to an interface would take a while.  Does Linux support binding a whole block of addresses to an interface?


Find the limit of the following sequence.  $$a_n = \frac{\sqrt[n]{(n+1)(n+2)...(2n)}}{n}$$  I tried couple of methods: Stolz, Squeeze, D'Alambert. But I can not seem to make a conclusion on the limit.

I'd like a hint to show that:  $$\lim \frac{1}{n} \sqrt[n]{(n+1)(n+2) \cdots 2n} = \frac{4}{e} .$$  Thanks.


Is it referenced anywhere that CSS classes with names start with numbers doesn't work? for example I found that a class with background like:  .000000-8 {background:url(../../images/common/000000-0.8.png);} .8FFFFFF {background:url(../../images/common/FFFFFF-0.8.png);}   doesn't work in most browsers I have and the  shows that but my question is there a workaround to make CSS classes with names that start with numbers valid? .

What characters/symbols are allowed within the CSS class selectors? I know that the following characters are invalid, but what characters are valid?  ~ ! @ $ % ^ & * ( ) + = , . / ' ; : " ? > < [ ] \ { } | ` #


I have an esta.  I am flying into USA, staying overnight before travelling to Canada by land arriving in Canada 12 hours later. I will be in Canada 100 days. Will I be able to return by land to USA to allow me to fly home?

I'm Australian and have obtained my Canadian working visa. However rather than flying direct to Canada I am meeting an American friend in LA and driving across the border. I have a return flight booked back to Australia from LA in March of next year too. Will the esta visa will be enough to enter the USA because I have my Canadian working visa and plan to travel there? Or will there be a problem because my return flight is booked later then the 90 days allowed on the visa.


I just bought a new laptop, it's ASUS TUF FX505DT, here's the specs:  AMD® Ryzen™ 5 3550H Processor DDR4 2400MHz SDRAM NVIDIA® GeForce® GTX 1650 , with 4GB GDDR5 VRAM 256GB PCIe® Gen3 SSD  I was wondering if this would work well if I'd switch my OS to Linux, Ubuntu to be specific. I'm running Ubuntu on my old laptop (it's HP Pavilion), and Linux is working well on it. I figured out to ask others who have the same laptop as mine if Linux does work well in this laptop before I switch Windows to Linux. I also heard that NVIDIA doesn't work well with Linux.

I have a device on which I would like to install Ubuntu. How do I find out if Ubuntu will work on it?


I guess that  $\mathbb{Z}[i]/\langle 2+i\rangle$ is equal to $\mathbb{Z}_5[i]$ if it is a simple extension of $\mathbb{Z}_5$. Based on this thought, I tried to construct a surjective ring homomorphism $\varphi$ from $\mathbb{Z}[i]$ to $\mathbb{Z}_5[i]$ with a kernel $\langle 2+i\rangle$. I know that $\mathbb{Z}[i]$ is a Euclidean domain, so it makes sense for me to think $\varphi(z)$ as the "remainder" when $z$ is divided by $2+i$. But how can I express the map $\varphi$ explicitly? Thanks.

A very basic ring theory question, which I am not able to solve. How does one show that    $\mathbb{Z}[i]/(3-i) \cong \mathbb{Z}/10\mathbb{Z}$. Extending the result: $\mathbb{Z}[i]/(a-ib) \cong \mathbb{Z}/(a^{2}+b^{2})\mathbb{Z}$, if $a,b$ are relatively prime.   My attempt was to define a map, $\varphi:\mathbb{Z}[i] \to \mathbb{Z}/10\mathbb{Z}$ and show that the kernel is the ideal generated by $\langle{3-i\rangle}$. But I couldn't think of such a map. Anyhow, any ideas would be helpful.


[click here for image of question][1]      [1]:       The question states: in this problem we will only consider (real- valued) function with domain $\mathbb{R}$ (real numbers). We define two new concepts. Let $f$ and $g$ be two functions;         we say $f$ is a rival of $g$ if $∃x∈ \mathbb{R}, s.t. ∀y∈ \mathbb{R}, x< y \text{ then } |f(x)-g(x)|<|f(y)-g(y)|$   we say $f$ is a frenemy of $g$ if   $∀x∈ \mathbb{R}, ∃y∈ \mathbb{R}, s.t. x< y \text{ AND } |f(x)-g(x)|<|f(y)-g(y)|$         a) Is the claim “ if $f$ and $g$ are any two functions and $f$ is a rival of $g$ then $f$ is a frenemy of $g$” true or false? If it’s true, prove it, if it’s false then show it with a counter example.   Can someone please show me how to solve for the first question a)? For the the two concepts defined, do I have to first find out if they are true or false before finding if the claims are correct? Is it technically saying that there’s a real number smaller than all other real numbers(y)?

In this problem, we will only consider (real-valued) functions with domain $\mathbb{R}$. We define two new concepts. Let $f$, and $g$ be two functions.  We say $f$ is a rival of $g$ if        $\exists x\in \mathbb{R} \ \text{s.t.} \ \forall y\in \mathbb{R}, x \lt y \implies \lvert f(x)- g(x)\rvert\lt\lvert f(y)-g(y)\rvert$    We say $f$ is a frenemy of $g$ if       $\forall x\in\mathbb{R} \ \text{s.t.} \ \  x \lt y \ \ \text{AND} \ \ \lvert f(x)-g(x)\rvert \lt \lvert f(y)-g(y)\rvert$  Below are four claims. Which ones are true and which ones are false? If a claim is true prove it. If a claim is false, show it with a counterexample.  a) If $f$ and $g$ are any two functions and $f$ is a rival of $g$ then $f$ is a frenemy of $g$. b) If $f$ and $g$ are any two functions and $f$ is a frenemy of $g$ then $f$ is a rival of $g$. If $f$ and $g$ are any two functions and $f$ is a rival of $g$, then $g$ is a rival of $f$. Let $f$, $g$, and $h$ be any three functions. If $f$ is a frenemy of $g$ and $g$ is a frenemy of $h$ then $f$ is a frenemy of $h$  What are the four claims stating? Especially for c), the concept is not even present I am having a misunderstanding on how to solve them?


I am trying to represent trade flows on a world map where the size and direction of arrows indicate the exports/imports of a given country.  This type of map is commonly found in magazines and newspapers. However, I find it extremely difficult to make.   Is there any function in ArcGIS for Desktop or any free software that would help me in making it?

For a project I'm working on, I need to represent network flows over 1,000 zones with directionality.    Any suggestions on displaying the information in a nice and non overwhelming way?  Any examples on displaying network flows in heavy urban areas? Color suggestions and thickness schemes? any "not to dos" when representing network flows?


Lets $n=pq$ with $p$ and $q$ primes   If we know the result of $p+q$, can we factorize $n$ in polynomial time ?  Best regards.

Can someone help me with the following question?  The sum of two numbers is $18$ and their product is $45$. Find the numbers.  I know that the answer is $15$ and $3$. But how do I find that answer algebraically? It tried doing it as $x+y=18$ and $xy=45$ and then $x= 18-y$ and I substituted in $xy=45$. I got it as $(18-y)y =45$, and I don't know what to do next.


I have been in France for one year on a national French visa. I would like to visit the Netherlands at the end of the trip and fly home (to a non Schengen country) from there. Should I expect any problems? Will having receipts from France, to prove I had not been in the Netherlands longer than a couple days, be enough?

I’m going to Germany for a semester exchange and I have a long-stay visa from Germany. Can I travel to the other Schengen states during this period with this visa or do I have to apply for a separate short stay Schengen visa?  My visa is German national visa type D. It is for a duration of 4 months, i.e., longer than 90 days. It says on the visa that the long stay visa is valid in Deutschland, which is different from my earlier visa, which I had when I visited Germany earlier; that one was a short stay visa and said it was valid in Schengen Staten.  Perhaps my current visa means that I can stay in Germany for a period of longer that 90 days can visit the other Schengen states if I don’t exceed the 90 day period.


What am I doing when I search for something on the internet and the search provides for some other interesting stuff apart from what I was looking for and I end up opening an infinite number of browser tabs and browsing more and more it goes in an endless loop and the whole episode makes for after thought to ponder upon.  PS: I lost the term I had found on Wikipedia and I cannot get it back.

What is the term for embarking on an internet search that leads from one website to another, to another, to a totally different site of non-related subject, based on information found in each subsequent search? Say, start looking at recipes initially and end up on Mediaeval monks, via early explorers, or whatever...hopping around all over the place and finding that a day has passed without your realising it.


Is there any file manager for Linux with a view style similar to that of "List" in Windows Explorer? i.e: in the screenshot I have set it to "List" and sorted by type. In my couple decades of checking out Linux distros every now and then I've yet to see this feature in the file managers.

How can I make "compact view" the default for all directory views in File Manager, instead of "icon view" ?


I have the following schema. CREATE TABLE `users`(                 id INT PRIMARY KEY AUTO_INCREMENT,                 steamid64 varchar(255) NOT NULL UNIQUE,                 steamid varchar(255) NOT NULL UNIQUE,                 name varchar(255),                 callsign varchar(255),                 qualifications LONGTEXT NULL,                 is_hidden BOOLEAN NOT NULL DEFAULT 0             );        CREATE TABLE `medals`(                 id INT PRIMARY KEY AUTO_INCREMENT,                 name varchar(255),                 description LONGTEXT,                 image TEXT,                 hierarchy INT UNIQUE NOT NULL             );          CREATE TABLE `has_medals`(                 id INT PRIMARY KEY AUTO_INCREMENT,                 medal_id INT,                 user_steamid64 varchar(255),                 issued_by_steamid64 varchar(255),                 FOREIGN KEY (user_steamid64) REFERENCES users(steamid64),                 FOREIGN KEY (medal_id) REFERENCES medals(id),                 FOREIGN KEY (issued_by_steamid64) REFERENCES users(steamid64)             );                          INSERT INTO users(id, steamid64, steamid, name, callsign)             VALUES (1, '76561198152109175', 'STEAM_0:1:95921723', 'vin', 'lorem ispum');                          INSERT INTO users(id, steamid64, steamid, name, callsign)             VALUES (2, '76561198163953541', 'STEAM_0:1:101843906', 'cleveland', 'lorem ispum');                          INSERT INTO medals(id, name, description, image, hierarchy)             VALUES (1, 'Test Medal', 'A Test Medal', 'http://google.com', 1);                          INSERT INTO has_medals(id, medal_id, user_steamid64, issued_by_steamid64)             VALUES (1, 1, '76561198152109175', '76561198163953541');  What I'm trying to do is get a result like this from a query based on a conditional select clause of finding all the medals a user has, the medals info, and all the user info from who gave them the medal.     id medal_id medal_name medal_description medal_image medal_hierarchy belongs_to_sid64 belongs_to_sid belongs_to_name belongs_to_callsign belongs_to_qualifications belongs_to_is_hidden issued_by_sid64 issued_by_sid issued_by_name issued_by_callsign issued_by_qualifications issued_by_is_hidden     I'm at a complete loss on how to do this. I tried messing around with some joins and stuff and couldn't get how I needed it. Can anyone help out? Here's an sql fiddle if anyone needs

I have 2 tables. One (domains) has domain ids, and domain names (dom_id, dom_url).  the other contains actual data, 2 of which columns require a TO and FROM domain names. So I have 2 columns rev_dom_from and rev_dom_for, both of which store the domain name id, from the domains table.  Simple.  Now I need to actually display both domain names on the webpage. I know how to display one or the other, via the LEFT JOIN domains ON reviews.rev_dom_for = domains.dom_url query, and then you echo out the dom_url, which would echo out the domain name in the rev_dom_for column.  But how would I make it echo out the 2nd domain name, in the dom_rev_from column?


I have an ArcSDE error: " **Failed to connect to database. Maximum number of connections to instance exceeded "*  Did what ESRI recommended :"      Check the value set for the CONNECTIONS parameter in the SERVER_CONFIG   or sde_server_config ArcSDE system table to be sure it is sufficient.   If it is not, increase the number of allowed connections using the   sdeconfig command with the alter operation"   and still nothing works on my database server. (I can't create features, import, etc).  We use a Microsoft SQL Server. And it's an enterprise geodatabase.     Apparently it was a schema lock. I had a map service started which used that geodatabase. So how can I edit the geodatabase and have a started map service in the same time. I've already created several versions and tried to publish just the versions, but they still lock my gdb.

We routinely exceed ArcSDE's connection limit, about once a week. Many of the "connections" are nothing but orphaned records in the SDE.PROCESS_INFORMATION table. Is there any way to clean up these connections periodically? I just service packed ArcSDE to 9.3.1 SP2, hoping this would resolve the problem. (It did not.) Currently I restart the arcsde service to clean up the connections, a pretty inelegant solution.  This is the error, by the way:  Failed to connect to database. Maximum number of connections to instance exceeded  My workaround:  My solution was simple: restart the SDE service weekly, and double the number of allowed connections. This is of course not a solution; shame on ESRI for shipping enterprise software that requires such a workaround. After all, it's still possible to exceed the maximum connections; I can only hope that our current level of use doesn't lead to this.  I altered the init.d script to prevent sdemon from prompting the user to confirm they want to stop the service (this is what the -N argument does). I added a restart option as well.  #!/bin/bash # # arcsde Init file for starting and stopping ArcSDE 9.3 # # chkconfig: 35 90 40 # description: ArcSDE startup script  # Source function library.  . /etc/rc.d/init.d/functions  SDE_OWNER="sde" SDEHOME="/home/sde/sdeexe93"  case "$1" in start) echo -n $"Starting ArcSDE:" su - $SDE_OWNER -c "$SDEHOME/bin/sdemon -o start -p pwd" echo "OK" ;; stop) echo -n $"Stopping ArcSDE:" su - $SDE_OWNER -c "$SDEHOME/bin/sdemon -o shutdown -p pwd -N" echo "OK" ;; restart) cd "$CWD" $0 stop sleep 5 $0 start ;; *) echo $"Usage: $0 {start|stop|restart}" esac   Then I created a cron job to restart the service once weekly:  # restart arcsde once weekly at 5am Saturdays 0 5 * * 6 service arcsde restart   I also increased the maximum number of allowed connections from 64 to 128 by editing the $SDEHOME/etc/giomgr.defs file:  CONNECTIONS      128     # maximum number of connections                          # NOTE:  On windows machines, you may need to                          # increase server non-interactive desktop memory.                          # Consult the ESRI support site for more information.   Then I imported the new settings:  $ sdeconfig -o import -f $SDEHOME/etc/giomgr.defs -i esri_sde -u sde   That was it. We'll see how it goes.


I want to know why we have two things "sudo apt upgrade" and "sudo apt -y upgrade"

I always see commands like this  apt-get -y install    What is the -y tag for and what is the difference between apt-get install with and without the -y tag?


I am new to ubuntu. During installation of Ubuntu 15.04 vivid vervet , I created partitions for ubuntu filesystem as Ext2 using windows partitioning tool.I created partitions for Boot loader information and ubuntu file system. After ubuntu installation, ubuntu partitions are showing in windows as local disks ,but not readable. When I tried to open it, a message that the partition is corrupted was shown and asked to format the disk. I dont want access for ubuntu file from windows.   What is the cause of this ? How can I hide this ubuntu partition in windows ?

I am running a dual-boot with Windows XP and Ubuntu 11.04.  Ubuntu has Open Office as part of the install. Occasionally, when using XP, I need to work on a spreadsheet or other Open Office document but can't seem to access them while using Windows XP. Is there a way that XP can crossover to Ubuntu documents?  Are two different versions of Adobe also needed?


Given: Let $n$ be an integer. Then $n^2=3a$ for some integer $a$ if and only if $n=3b$ for some integer $b$.  Proof real number $\sqrt{3}$ is an irrational number.  Here is I have so far: Assume $\sqrt{3}=a/b$ where $a,b$ are integers.  Then $a^2=3(b^2)$, which means $a^2=3c$, where $c$ is some integer.  next is what I'm confused about: With the given fact I can get $a=3d$ where $d$ is integer in order to let $a^2=3c$  I'm not quite sure how to continue this.. Can someone please help?

Prove $\sqrt{3}$ is irrational. (Proof by contradiction).  Let $\sqrt{3}$ be a rational number in simplest form $\frac pq$.   So squaring both sides of $\sqrt{3}=\frac pq$ we get $3=(\frac {p}{q})^2$ which translates to $3=\frac{p^2}{q^2}$.   Multiply both sides of the equation by $q^2$ yields $3q^2=p^2$. Now $p^2$ is taken to be divisible by 3 and thus an odd number, $p$ is also odd because any odd number squared is also odd.   So let $p=3s$ where s is an integer. Then $3q^2=(3s)^2 = 3q^2=9s^2$. Dividing both sides of the equation by 3 leaves us with $q^2=3s^2$.   Here is is taken that $q^2$ is divisible by 3 and is odd and so is $q$.   Therefore both $q \text{ and}\; p$ have a common factor of being odd and divisible by 3, proving that the $\sqrt{3}$ is irrational.  Are there any gaps that I could improve on?


showed up in the close review queue for C++:    I was leaving a comment as to the inappropriateness of the c++ tag for this question, when I went to the question and found this:    The question does not have the c++ tag, and has never been revised.  Surely any ninja revision would be over a week old, far too old to influence the close queue filtering.  Diamond mod Oded was able to confirm that the honeypot messes with tags sometimes.  That's bad, because it messes with the quality of the question and you can no longer make a judgement about the user's reaction when you show them an alternate version of the question.  In this case I was leaving a negative comment using the review queue, and it did show up on the real question!  Of course I deleted it because I realized that it wasn't deserved, but if I was only paying enough attention to decide the question was ok (I do know enough Java for that), then I might not have visited the question.  If you're going to make a fake version of a question to show the reviewer, then review actions including commenting need to be disassociated from the real question.  In order to not discard useful comments, you may need to drop the facade if the reviewer tries to leave a comment, and send them to the real question to decide whether it still applies.  Related but different:  (different because there the system recognized that the tag wasn't present, and passed it through the filter anyway)  Edit: Neither of the linked questions, or answers, address comments left on faked answers via the review audit system.  There's a solitary comment that mentions the issue, but nothing is resolved, since it isn't answered.  This bug report is separate from those two.

Just recently the . I've got  this morning which seems to be out of scope for my filtered list. I have filtered my list to only review VBA and Excel-VBA tags while the audit is tagged with perl http pipes which have nothing in common with VBA. I see a problem with the way the system currently works  Since I have a filtered list of tags, once I see a differently tagged question I already know it's an audit. Come on, that's too easy!  Can this please be fixed? update I have ran into  which I decided to edit - the question was tagged VBA and I thought it had nothing to do with VBA so I selected Edit which was the correct action. Now, once the first audit was clearly one to close - nothing to do with VBA and really easy to know that it actually was an audit - the second one was a very good audit. I am just thinking now if this is a proper bug or just a matter of malfunction in the system. I think the first one may have been made an audit for the wrong reason. Let's turn this into a discussion as I can't clearly work the system out.


I am trying to check if any child from Firebase Realtime Database matching data in sqlite database in my app with help of SQLiteAssetHelper. For this I wrote a function to check but it is returning NullPointerException error.   I have Check adding taskId in database manually, but still it is returning null value.  Error  ava.lang.NullPointerException: Attempt to invoke virtual method 'boolean mypackage.CompletedTasks.isComplete(java.lang.String)' on a null object reference   SQLiteAssetHelper Method  public boolean isComplete(String taskId) {     SQLiteDatabase favDatabase = getReadableDatabase();     String masterQuery = String.format("SELECT * FROM completedTasks      WHERE taskId = '%s'",             taskId);     Cursor cursor = favDatabase.rawQuery(masterQuery, null);     if (cursor.getCount() <= 0) {         cursor.close();         return false;     }     cursor.close();     return true; }   Check in onBindViewHolder  if (completedTasks.isComplete(adapter.getRef(position).getKey())) {         holder.taskCard.setVisibility(View.GONE); } else {         holder.taskCard.setVisibility(View.VISIBLE); }

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


I was studying probability and came across this statement:  If $h(x)$ is a convex function, that is, for $0 \le \alpha \le 1$ $$h(\alpha x_1 + (1 - \alpha)x_2) \le \alpha h(x_1) + (1 - \alpha)h(x_2)$$ for example $h(x) = x^2$ or $h(x) = e^x$, then for any $x_0$ there always exists a $b$ such that the line $h(x_0) + b(x - x_0)$ lies below $h(x)$, that is $$h(x) \ge h(x_0) + b(x - x_0)$$ for any $x$. In particular, $h(X) \ge h(EX) + b(X - EX)$ for some $b$.  This entire thing looks like nonsense to me. The claims that it makes do not follow (are not implied by) the previous statements. For instance, it says that $h(\alpha x_1 + (1 - \alpha)x_2) \le \alpha h(x_1) + (1 - \alpha)h(x_2)$, but then it says that this implies that $h(x) \ge h(x_0) + b(x - x_0)$, which is at least unclear. Could someone please clear this up, so that I can understand what point it's trying to make? Thank you.

$f:I \to \mathbb R$ is a convex function on an open interval $I$. I know that if $f$ is differentiable on $I$, then $\forall x_0,x \in I , f(x_0)+f'(x_0)(x-x_0) \le f(x)$  I read somewhere that something similar true even if $f$ is not differentiable, i.e. $\exists a \in \mathbb R: \forall x_0, x \in I, f(x) \ge a(x-x_0)+f(x_0)$.  Does anybody know a proof for that? It would e.g. help to show that $\forall x_0 \in I$ there is a convex differentiable function $g:I \to \mathbb R, g(x_0)=f(x_0)$ and  $\forall x \in I,  g(x) \le f(x)$


I want to get BIOS information and print information about all structures.  How to get via command-line?

It's pretty easy to check the release date of BIOS version directly from the terminal emulator using a simple single command. So how to do that?


Update 2: It looks like this is finally getting addressed (see ) - I'm quite happy that Jeff has reconsidered this indeed as envisioned in  back in July 2010, and will accept it accordingly, once the decision is final, i.e. the discussion has settled a bit :)  Update 1: While analyzing the count of remaining questions tagged superuser (67 vs. ~295 migrated), serverfault (69 vs. ~110 migrated) or stackoverflow (1517 vs. 12873 total) I just found the question , and  at least touches part of the topic regarding naming implications when referring to Stack Overflow Inc. vs. Stack Exchange Network/sites. While this backs my assumption of the subject matter being decided finally for somewhat personal reasons already (though the phrase For now implies here's hoping ;) I'll still keep the question and arguments below as they are addressing the topic in particular and from a different angle after  have fortunately materialized for Server Fault and Super User at least.  I really applaud your recent announcement to have  from now on for Super User and Server Fault too, as well as migrating lots of questions from here over there accordingly already. Now, I'm pretty sure you have thought this through several times already (haven't found any recent discussion of this though) and are in fact explaining why your are not doing the same for Stack Overflow itself:  For now we are leaving meta.stackoverflow.com grandfathered in, as-is, with no changes; it’s still a standalone community with a standalone reputation system. We think Stack Overflow is large enough to justify this, and it just so happens that Stack Overflow is also the name of the company, too. Meta Stack Overflow will serve as the “National Capital” where we process feedback not just for Stack Overflow but for the core engine itself — while the smaller meta sites are akin to regional or state capitals.  These arguments are understandable and justified regarding having a “National Capital” where we process feedback [...] for the core engine itself as such, and having a standalone community with a standalone reputation system for this very purpose is probably just fine and not the issue here. However, I still don't get why this means keeping this lone inconsistency and staying at odds with the  for all future users of the Stack Exchange Network (and we all hope there will be millions, aren't we?) by sticking to meta.stackoverflow.com rather than making the obvious switch to meta.stackexchange.com and migrating Stack Overflow only related question back to the thus free per-site meta.stackoverflow.com afterwards, just like for Super User and Server Fault right now? I think my point is obvious, and I'm ready to take the potential downvotes (though I don't think these will be necessarily, a polite argument, or even just a 'because we wanna' will be sufficient, I can't and won't argue about that ;) - still here are some arguments in favor of the switch:  As outlined already you will gain a consistent Meta experience within the Stack Exchange Network from now on for all future users. You will gain consistency with your section Proper Use of the Stack Overflow and Stack Exchange Name as outlined on the : You'll have Stack Exchange [network|sites|API] and, a perfect match, a dedicated standalone community with a standalone reputation system for all things meta regarding these entities. The poor homeless posts living on meta.stackexchange.com right now would finally find a new home, where they will be most welcome and just feel, well, at home ;) [I realize there might be some issues for sites staying on Stack Exchange 1.0 eventually though] The  regarding  might be easier to resolve as well in the long run ;)  Well, I'm going to bed now and hope my morning coffee will be strong enough for the outcome of this instant questioning into the most recent decision of the  ;)

Update 2014-04-17 04:47 UTC: Stable, with some odds and ends to clean up      The main MSO/MSE sites are stable, but there are plenty of corners left to sweep. For details, see:    Not all of them mind you, just Meta Stack Overflow into Meta Stack Exchange.  I'll have you know, factually, that we really did believe this would take place in six-to-eight weeks when it was , but we've finally got a tentative date established.  If things go according to plan, we'll begin the operation shortly after 8:30 PM EDT on the 16th, completing everything within a few hour window. Ideally, all service disrupting endeavors will be completed within the first hour, which include:   The availability of Meta Stack Overflow The availability of Stack Overflow (more on this shortly) The availability of Chat on Meta Stack Overflow   As you know, we'll be bolting on a standard issue per-site meta on Stack Overflow, while breaking the link between what will have become Meta Stack Exchange and Stack Overflow. There's some irritable innards in that particular region, so we'll be asking folks to expect the unexpected during the maintenance window. Affected sites will be in and out of read-only mode, or quite possibly just down for maintenance while we're doing the actual break.  I'll be posting a system message on both Meta Stack Overflow as well as Stack Overflow itself 24 hours before we begin the actual work.   Did I say tentative in a six-to-eight-something time frame again? Why yes, I did - we're currently running some tests on the dev tier to simulate the split as closely as possible, so that we can better anticipate quirks that we need to address prior to actually doing it.  Once the sites have actually been stood up functionally on the production tier, we're going to get to work on finishing touches. This will include things like site settings (which determine bits of text you see in the question prompts, rep thresholds, etc) and all sorts of other fine tuning.  Once we're done:   Stack Overflow will have a blank, empty child meta site just like every other site The new Meta Stack Exchange will be up and running All rooms on Chat Meta Stack Overflow will be moved to Chat Meta Stack Exchange  I'll send over about 150 - 200 questions from MSE to MSO, most of which will be tag or SO-specific feature related posts that got buried by the network stuff without resolution.   If the tentative date moves, I'll update this post with the new date. However, we do not anticipate this happening any later than Saturday, April 19 - in the case that we see down time we can't mitigate and need to do it on a weekend.  The ground work is basically done, we're finishing up sanity now with a great deal of confidence, and we're pretty certain that we'll hit between those dates, if not directly on the tentative 16th.  Questions? Kvetch? Anonymous confessions? Answer below, and I'll address each in comments.


I am a complete beginner and following a tutorial about how to put a texture on a cube. I think maybe they have a different version of Blender because what I see in a few places is different so it is very hard to follow.  In the video after UV unwrapping the cube they click to create a new material then click this little button next to the colour and then get a menu where they can choose 'Image texture'    But in my Blender which is 2.79b when I click Add material it looks like this:    As you can see it is totally different and I can't find anywhere a Color box with a button like in the video. I can't even see 'Surface' anywhere. So I am stuck.   Did they change Blender so much I need to find a new tutorial for my version? Is there a simple way to do the same thing in the version I have?

Complete beginner here.  I'm trying to follow  tutorial on Anisotropic shaders, but my property panel looks nothing like the property panel in the tutorial.  For example, when creating a material, this is what his property panel looks like:    But this is what mine looks like, if I follow the same path:    I'm sure I'm missing something obvious.  How can I see the property panel shown in the tutorial?


I was once shown that if a black hole with the mass of our Sun replaced our Sun in the solar system (I believe it was in a simulation program), the attraction it has on the planets will be the same because the distance between the planets and centre of mass is the same, regardless of the density. How well does this hold up to more accurate mathematics of physics such as GR, because I was shown this in the context of Newtonian Mechanics?

The gravitational force on your body, called your weight, pushes you down onto the floor. $$W=mg$$ So, what is the weight equation through general relativity?


I wrote an authenticator to see if an email ends with "@gmail.com". I don't really know why is this returns false. Could someone help me out why is it?   public static void main(String [] args){     System.out.println(StringUtils.isValidGmail("a@gmail.com"));  // true }   public static boolean isValidGmail(String email){     if (email == null){         return false;     }     int x = email.length() - 1;     String gmail = email.substring(x-9, x+1);  // @gmail.com     return gmail == "@gmail.com"; }

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


This app crashes on launch, more specifically in the getAllData method, I'm recieving this error, im att loss, what to do?  Attempt to invoke virtual method 'android.database.Cursor com.example.arman.yourstep.DatabaseHelper.getAllData()' on a null object reference   here is the broadcastreceiver class  public class MyBootReceiver extends BroadcastReceiver {  @Override public void onReceive(Context context, Intent intent) {      if(intent.getAction().equals("android.intent.action.BOOT_COMPLETED")) {         Intent i = new Intent(context, MainActivity.class);         i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);         context.startActivity(i);     }else  if(intent.getAction().equals("android.intent.action.DATE_CHANGED")){         StatsActivity sa = new StatsActivity();         sa.newday();     } }   }  here is the mainactivity class  public class MainActivity extends AppCompatActivity implements SensorEventListener{   private StatsActivity sa;  @Override protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_main);     Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);     setSupportActionBar(toolbar);     count = (TextView)findViewById(R.id.count);     sensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);      sa = new StatsActivity();   @Override public void onSensorChanged(SensorEvent event){     if(activityWalk){         count.setText(String.valueOf(event.values[0]));         steps = event.values[0];         sa.newStep();      }     if (event.values [0] == 10000){         notificationManager.notify(1337,builder.build());     }  }   here is the statsactivity class that holds the stats  public class StatsActivity extends AppCompatActivity  { private TextView avgStep, totalStep, meterStep; private int steps,days; private DatabaseHelper dBase;  @Override protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_stats);     Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);     setSupportActionBar(toolbar);     dBase = new DatabaseHelper(this);      getStats();      avgStep = (TextView)findViewById(R.id.avgCount);     totalStep = (TextView)findViewById(R.id.totalCount);     meterStep = (TextView)findViewById(R.id.meterCount);      float meter = new Float(0.762);      meterStep.setText(Float.toString(steps * meter));     totalStep.setText(Float.toString(steps));     avgStep.setText(Float.toString(steps / days)); }  private void getStats(){     Cursor result = dBase.getAllData();     if (result.getCount()==0){         //Make error handling     }     try {         days = result.getInt(0);   //here is where i crash         steps = result.getInt(1);     }catch (Exception e){         Log.d("db", e.getMessage());     }     result.close(); }  public int getDays(){     getStats();     return days; }  public int getSteps(){     getStats();     return steps; }  public void newday(){     getStats();     days++;     dBase.insertData(days, steps); }  public void newStep(){     getStats();     steps++;     dBase.insertData(days, steps); }   }  hopefully someone can see what I'm doing wrong.


What's the advantage of doing this:  namespace a {     using System;      class ClassA     {      } }   over this  using System;  namespace a {      class ClassA      {      } }   is there any performance advantage or best practices?

I have been running  over some C# code, and it keeps reporting that my using directives should be inside the namespace.  Is there a technical reason for putting the using directives inside instead of outside the namespace?


I am using public class DatabaseHandler that extends SQLiteOpenHelper and this is my method to get all the data from the db, it looks all fine but crashes, and activity says nullpointerException. Is there anything to change in the code? I have only one row of information..  // Getting all data  public Cursor getData(String UserName, String Email, String Password,         String BirthDate, String PinCode, String Country, String PaypalID,         String mobile, String FBID) {      SQLiteDatabase db = this.getReadableDatabase();      Cursor cursor = db.query(TABLE_DATA, new String[] { "UserName",             "Email", "Password", "BirthDate", "PinCode", "Country",             "PaypalID", "mNUMBER", "FBID" }, null, null, null, null, null,             null);      if (cursor != null) {          if (cursor.moveToFirst()) {             do {                 Log.i("counttttttttttttt", "" + cursor.getCount());                  UserName = cursor.getString(0);                 Email = cursor.getString(1);                 Password = cursor.getString(2);                 BirthDate = cursor.getString(3);                 PinCode = cursor.getString(4);                 Country = cursor.getString(5);                 PaypalID = cursor.getString(6);                 mobile = cursor.getString(7);                 FBID = cursor.getString(8);              } while (cursor.moveToNext());         }     }      db.close();     return cursor; }   In, Account Activity,  db = new DatabaseHandler(AccountActivity.this);     // Declared all String      db.getData(name, email, password, birthdate, pincode, country, paypal,             mobile, fbid);   and set those String to TextView as required..  but it says nullpointer exception.


This is the output I get while trying the sudo apt-get update Running Ubuntu 16.10  E: Could not get lock /var/lib/apt/lists/lock - open (11: Resource temporarily unavailable) E: Unable to lock directory /var/lib/apt/lists/ E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable) E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?

I get this error when trying to use apt-get:  E: Could not get lock /var/lib/dpkg/lock - open (11 Resource temporarily unavailable) E: Unable to lock the administration directory (/var/lib/dpkg/) is another process using it?     How can I fix this?


I have no idea how to solve this problem. I know that the definition states that a series $$\sum^\infty_{k=1}=a_1+a_2+a_3+a_4+........$$ is convergent if the sequence of partial sums $$S_n=a_1+a_2+a_3+......+a_n = \sum_{k=1}^n a_k$$ converges to a limit, so $$\lim_{n\to\infty}S_n$$ And the limit is called the sum of the series denoted by $$\sum_{k=1}^{\infty}a_k=S$$ However, i do not then know how to implement this into other promblems like the one below, $$\sum^{\infty}_{n=0}p^n$$ Thank you.

Why does the following hold:  \begin{equation*} \displaystyle \sum\limits_{n=0}^{\infty} 0.7^n=\frac{1}{1-0.7} = 10/3\quad ? \end{equation*}  Can we generalize the above to      $\displaystyle \sum_{n=0}^{\infty} x^n = \frac{1}{1-x}$ ?   Are there some values of $x$ for which the above formula is invalid?  What about if we take only a finite number of terms? Is there a simpler formula?     $\displaystyle \sum_{n=0}^{N} x^n$   Is there a name for such a sequence?    This is being repurposed in an effort to cut down on duplicates, see here: Coping with  duplicate questions.  and here: .


So, I have to solve the limit problem using a derivative.  The problem is as follows: $$\lim_{x\to0}\frac{(1+x)^{1/x}-e}{x}$$  I really don't know what to do. Can someone help?

Find the following limit: $$\lim_{x\to 0}\frac{(1+x)^{1/x}-e}{x} \tag{1}$$  The following is my approach, although is full of incorrect assumptions (statements etc).  $$f(x)= \lim_{h\to 0}(1+x+h)^{1/(x+h)}\\$$  From here we can say $f(0) = e$.  $$\ln(f(x)) = \lim_{h\to 0}\frac{1}{x+h}\ln(1+x+h)$$  Near $x=0$, we can use the series of logarithm: $$\ln(f(x)) = \lim_{h\to 0}\frac{1}{x+h}\left(x+h-\frac{(x+h)^2}{2}...\right)$$  Differentiating we get:  $$\frac{f'(x)}{f(x)} = \lim_{h\to 0}-\frac{1}{2} +\frac{x+h}{3}  ... \tag{2}$$  Now we note that $(1)$ is actually $f'(0)$ (?) and so from $(2)$ we get:  $$f'(0) =\frac{-1}{2} f(0) = \frac{-e}{2}$$  While the answer is seemingly correct, the method is absolutely not. It looks like this is fluke than anything else.  I also tried computing taylor series of $(1+x)^{1/x}$ near $x=0$ but couldn't do it.


In this answer  , step 3:     Ensure that the radeon module is blacklisted prior to installing the package from AMD.   How can I do that?  Kernel version (output of uname -r to be exact): 4.10.0-26-generic  Ubuntu 17.04

How do I disable loading of unnecessary kernel modules. Kernel 3.2.4


I have a question regarding these two terms. I undertand that for a problem to be well-posed, it needs to satisfy three conditions:   Existence of solution Unique solution Solution depends with continuity on the data (i.e. small perturbations of the data lead to small perturbations in the solution). I will refer to this as stability.   Then, once we have our well-posed problem, we can define whether it is well- or ill-conditioned, which as stability, also measures how much the solution changes with perturbations in the data.   Then, I am confused. Why are not all ill-conditioned problems ill-posed?  As an example, say we have to solve for x in a nonlinear continuous function, so our problem is $f(x)=0$. Then, if I found the condition number to tend to infinity, how could my problem ever be well-posed? My professor used this example in class and I was just mind struck.  Note: I have already gone through the post , which asks a slightly different question and has helped me a lot, but I still have a lot of confusion in me.

What's the difference between a well-posed (ill-posed) and well-conditioned (ill-conditioned) problem?  According to :     Even if a problem is well-posed, it may still be ill-conditioned, meaning that a small error in the initial data can result in much larger errors in the answers.


"Yeah-huh", "Nuh-uh".  "Ah."  "Oh."  "Um."   "Ew."  "Huh!"  "Huh?"  "Ehh." "I don't know."  Tone and breath are all that separate all of these 'm' sounds.  You can say a lot without opening your mouth.  Does this phenomenon have a name?

What is it called when one expresses "Yes", "No", or "I Don't Know" without using words - just humming their response?  You know, when someone responds with a low note than a high note for Yes or "Ah-huh!"; a low note and a slightly lower note for No or "Nuh-uh"; or a low note, a high note, and a low note for I don't know.


I'm pretty new to coding, and I understand how to do a do while for a yes or no answer in C++. But java is giving me a hard time. This code doesn't give me any errors until I run it. When it asks for the yes or no answer it will say:  Exception in thread "main" java.util.NoSuchElementException     at java.util.Scanner.throwFor(Unknown Source)     at java.util.Scanner.next(Unknown Source)     at midterm.main(midterm.java:40)   Line 40 is the:  ans = s.next();   Maybe I'm doing something wrong with String, I've tried char but had no luck either. Here is my code:   public class midterm  {     public static void main(String[] args)     {      Scanner s = new Scanner(System.in);      String ans;     do     {      System.out.println("Welcome to the Menu!\nA)Guessing Game\nB)Calculator\n"             + "\nEnter Letter: ");     String letter = s.next();     s.nextLine();      if ((letter.equals("A")) || (letter.equals("a")))     {         guessingGame();     }      else      {         calcDecide();     }      System.out.println("\nWould you like to go back to the menu or exit?\n"             + "Press 'Y' yes or 'E' for exit: ");     ans = s.next();     s.nextLine();      }while (ans == "y" || ans == "y");      s.close();  }   Not sure why this was marked as a duplicate. I feel that people don't read the entire thing and like to assume this. This WAS NOT a simple String mess-up(That's part of the mistake,) but there's a bigger issue here, which I believe to be the scanner

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


I have a question that somehow depends on people's taste I suppose. I like the amsart package for my documents, however I always found the margins too large, so I got used to making them smaller (3cm) using the geometry package.   When the article goes to a journal it doesn't matter in the end because they will format it accordingly, so my question is rather aimed at the preprint version, which is usually the one in the arxiv/home webpage.   What do people prefer generally? Big margins? Small margins?   Why does amsart sets the margin so large? I know it's for their journal specifications, so the question may be rephrased: what's the reason that these journals like the margins so big? I'm looking for an answer in the lines of "because it's better for reading according to such and such..".

I've read that—unless I know a lot about typesetting—I shouldn't change the margins of a LaTeX document. The default margin size of the article class is really big and it feels like a lot of space is waste. Thanks to the geometry package, it is simple to change the margins, but I'm not sure if I should.  Can someone tell me why the default margin size is so big? Also, why shouldn't I change the margin size?


I'm running Bionic 18.04.  I've tried several ways to upgrade without luck.  Any suggestions are appreciated. I've updated and tried sudo do-release-upgrade "Please install all available updates for your release before upgrading." Seems that libpoppler85 can't be upgraded.  It is held back.  Reportedly it is for 19.04.  So I tried apt-cache policy libpoppler85 libpoppler73 It returned the following - libpoppler73: Installed: 0.62.0-2ubuntu2.10 Repeated upgrade process without results. I also tried the Software Updater which said a new release (20.04 LTS) is available.  The update doesn't work either.  Just closes normally. sudo do-release-upgrade -d for me returns "Upgrades to the development release are only available from the latest supported release." Do I need to install from .ISO file? What else should I do? Thanks

I understand that the first point release of Ubuntu 18.04, namely 18.04.1 is now available and that my system should now offer it as an update.  My current OS version is 16.04.5 LTS. In System Settings/Software and Updates I have set 'Notify me of a new Ubuntu version' to 'For long term support versions'. I have tried both the main server and the server for United Kingdom, neither offers an update when Software Updater is clicked or via the Ubuntu Software icon.  Can anyone please tell me why I don't get the option of updating to 18.04?  Edit:  I don't remember the details exactly, but I think that my last LTS point release update was offered automatically a lot sooner after the published release date than where we are now with 18.04.1.  Edit 10th August  It appears that there has been some problem with the update process and that it should be fixed next week, see:    Edit 14th August 18.04.1 LTS now available from UK server,


Suppose there is a moderator on an unspecified Stack Exchange community who is sometimes, let us say, a little heavy handed—occasionally with very new members.   I understand that that is only my opinion. This moderator has never, to my recollection, moderated anything of mine so there is no personal axe to grind.    I know that being a moderator is not easy and I would in any case not challenge a decision openly.  Question  Is there a recognised feedback route through which one can express such concerns without disrupting the efficient operation and good-will that exists here?

One or more of the following things happened to me on a Stack Exchange site:   My post(s) were wrongly deleted or locked by a moderator A moderator posted a wrong comment on one of my posts I was suspended, but did not do anything wrong I asked a meta question, but the question was closed and/or deleted A moderator discredited me in public ...   I think a moderator has abused their power, but I feel powerless against them.  What recourse do I have now? What can I do when I feel that a moderator has abused their power, and has been repeatedly unfair in their dealings with me?


If G is a group of order p^n and N is a normal subgroup of order p where p is prime and n is natural number, then prove that N is contained in the center of G.

If $G$ is a finite $p$-group with a nontrivial normal subgroup $H$, then the intersection of $H$ and the center of $G$ is not trivial.


I have trouble when put an equation with exponents in the \chapter.  \documentclass{scrbook} \usepackage{classicthesis-ldpkg} \usepackage{amsmath}  \begin{document}  \chapter{Sistem A: $L(\dot{q}_2,\dot{q}_2)=\dot{q}_1^2+\dot{q}_2^{2}$}  \end{document}   But it gives me multiple errors that doesn't appear when I compile, in the index contents appears the equation if I change \chapter for \section instruction, but I need put this in the chapter. Any help?

For reasons that are beyond me, the following MWE  \documentclass{scrreprt} \usepackage{classicthesis-ldpkg} \usepackage{bm} \usepackage{amsmath}  \begin{document}  \section{The values of $\beta$ for which $\omega_i \mid \bm{\omega} \mid^{-\beta}$ is defined at the origin}  \end{document}   fails to compile with the following error:  ! TeX capacity exceeded, sorry [input stack size=5000]. <to be read again>                    \HyPsd@@LetCommand l.9 ...a} \mid^{-\beta}$ is defined at the origin}   I've tried increasing the amount of memory available to pdfLatex but that doesn't solve the problem. I've also googled to no avail. Is there a workaround for this problem.


Where is the dark mode folder icon located?  The Dark Mode is so cool, but the blue folder icon is too bright in the whole black background. The grey one would be better for me.  So how do I change the icon?  In the early version,（OS X 10.6-10.11，macOS 10.12-10.13） the path of the folder icon is /System/Library/CoreServices/CoreTypes.bundle/Contents/Resources  But in this folder, there is no Dark Mode folder icon. And, the icons of Light Mode are still here.     Who knows where I can find the dark icon, please?  An amazing thing is that when I use a grey folder icon that made by an artist in Deviantart.com to replace the icon of system itself(/System/Library/CoreServices/CoreTypes.bundle/Contents/Resources/GenericFolderIcon.icns), all the folder icons in finder windows had been changed into grey,and thay are light,the icon didn't change into dark mode with the system appearance. It seems that the icons that I think are only work in Light Mode are still work in the Dark Mode. But, they are available only in the files are system themselves.

In High Sierra I used some custom icons for my folders in the Finder; but with the new update to Mojave and the dark mode, the predefined icons also become darker. However the custom icons don't.  Inspecting an element you find a dark preview, but when you extract the icon this is the clear, the same as there was in High Sierra. E.g.:   Previously visualization of the developer predefined icon. It's dark:  But if you extract that icon, it's clear:    There are no dark icons in the system library, at least not in the same directory as always:  /System/Library/CoreServices/CoreTypes.bundle/Contents/Resources   Are they being actively obscured by the operative system without there being icons with that real appearance? In this case, any idea to apply this method to the custom icons without modifying it into a new coloration?


I am using Windows Server 2008 Enterprise with SQL Server 2008 Enterprise. I am considering whether using SAN or using NAS is better to store database data files. Are there any industry readings to compare whether NAS or SAN is better for database storage scenario?  Besides my database storage scenario, any industry readings to compare SAN with NAS to see which technology is better suitable for which scenario?  thanks in advance, George

I have to install a new Server with SQL Server 2008, What do you recommend, One server with Raid 10 or the Files in a NAS?  What about iSCSI should I use it?  What about SAN?  The server has 4Gb of RAM and that database file is about 2GB.  To make my self clear today the server has no RAID, I have to implement some kind of strategy so  if something happend I can have my files safe, so What should I choose Local Files, NAS, SAN? What  option has the most performance, what is the more secure?


I have an HTML table with 2 rows and 6 columns.  The last column has a Bootstrap button that when clicked, clones the last row and adds it to the table.  After a new last row is added to the table, I remove the button in the penultimate row.  My table is decorated with a class attribute called: advPayment.  Here is my HTML:

             Type	             Ref No.	             Amount	             Deposit Date	             Comment	             &nbsp;

             Cash	             12410008	             $175.00	             05-12-2015	             &nbsp;	             &nbsp;

             Check	             5561	             $325.00	             05-12-2015	             &nbsp;	             Add

    Here is my javascript:  $(".advPayment tbody tr:last td:last a").click(function(e) {     e.preventDefault();      $(".advPayment tbody tr").last().clone().appendTo(".advPayment");     var rowCount = $('table.advPayment tbody tr').length - 1;      // remove Add button from the second to the last row     $(".advPayment tbody tr:nth-child(" + rowCount + ") td:last a").remove();  });    The first time I click on the Add button, the code works.  The next time I click on the button, it doesn't work.  I have a feeling it's due to the way the jQuery button binding works, but I wanted to get a second opinion.  Is there another way to dynamically bind on the fly?

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 am asking very basic but deep questions related to programming, mathematics etc...   Unfortunately I am losing my reputation. Suggest for me the best site in the Stack Exchange network to ask questions like these:     Is a program written in any programming language ultimately a function/relation in math or not?

There seems to be more than a few computer science/programming Stack Exchange networks (is that the correct term?). Stack Overflow, being the first, has by far the most users, questions, and answers.  What is the reasoning for creating the others, and are there clear guidelines for which kinds of questions should be posted? I can see a large amount of potential overflow, many cases of people not getting a good answer to their question, because the person who has the answer isn't browsing that particular network at the moment.  I understand that they were probably created for organizational purposes, but wouldn't it almost make more sense to just have them as categories under Stack Overflow, keep them separated but still connected, instead of making people have to create multiple 'account's, one for each network?  I am sure there was a very good reason to break them up, but as someone that is new to SE, it can be somewhat intimidating to decide which one to post in to ensure you get a good answer. For example, if I am a computer science student, my first instinct might to be to post in the computer science network, until I see that it literally has 1% of the users as the Stack Overflow network, which still seems to be for programming/computer science related questions.  So my second instinct would then to be to post it into the Stack Overflow site on the basis that I have a significantly higher chance of my question being seen and getting a good answer. Then I notice that there is also a 'programmers' network, and I don't even begin to know where that fits in. I, and I am assuming most people, will probably just post on Stack Overflow to be safe.  My question is, other than the short little description blurb of each one, is there a clear cut set of guidelines which what each network is intended for, what kinds of questions should go to each one, and is anything being done to encourage people to post in these newer, smaller (more specialized?) networks as opposed to just posting in big daddy Stack Overflow?  Now again, this is for computer science/programming/"why isn't this code doing what I want?" related questions, I am not saying that if I had a question about Linux or WordPress or something I would have the same confusion.


When I was a child I was given this problem to send a wire from electricity, water, and internet to each of the houses, all three houses must have all three wires connected without being crossed over each other (wires can't meet and there is no such thing as a wire going on top of another wire) , I have always gotten to the point where I can connect all but except one wire.   Now after many years this just came to my mind today, and I wanted to ask why isn't it actually possible? What makes the last wire so special? That u can't connect the 9th wire in a 2D plane. Let me know if anyone know how to solve it or if anyone knows a proof (in layman terms) as to why it's Impossible.

There's a puzzle where you have 3 houses and 3 utilities. You must draw lines so that each house is connected to all three utilities, but the lines cannot overlap. However, I'm fairly sure that the puzzle is impossible. How is this proved?


Are there enough digital and/or analog difference in individual cameras/houses/lenses that photos will have fingerprint of sorts? For example discoloration of pixels, distortion from aberrations on lenses.  Imagine if you will that proving that an image (stripped of metadata) was taken with one specific camera would be critical to an investigation of some sort. If endlessly competent experts had full access to the camera and photo, and had every resource available, could they match a photo to a camera? Like a fired bullet to a gun.  When, or in what circumstance could a photograph be linked not only to a lens/house model or manufacturer but to one specific camera, distinguished from any other camera of the same model?    I guess a more general way of asking this question is: How much, and what information about the camera can a photograph capture?

Is it possible to identify images (without exif data) and link them to the exact same camera? If so, I'd like some software recommendations to get the job done.  I have two photos that I'd like to compare whether they were taken with the same camera or not. They both seem to lack EXIF data but I am sure I've heard of other hidden fingerprints to be found within the images.  For instance, sensor noise should be rather consistent if the photos were taken with the same camera, pretty much like firing a handgun and the bullet gets unique marks. I've also heard that the camera manufacturers sometimes add a hidden watermark which can be read with some special software.


I am a bit new to Ubuntu Unity here, and I'm having issues extracting the streamlink-twitch-gui file.  I've followed the  to put in in a tmp folder, but when I try to execute:  sudo tar -xzvf /tmp/streamlink-twitch-gui.tar.gz -C /opt   It comes back with:  gzip: stdin: not in gzip format tar: Child returned status 1 tar; Error is not recoverable: exiting now   I'm not sure why it isn't working; I double-checked my downloaded file, re-started my xterm and re-wrote the code, tried some other variations of the line like using xjf and xvf instead of -xzvf, and including the archive download url, but nothing.  Any help you could give me would be fantastic.

When I run:  tar -zxvf john-1.7.0.2.tar.gz   I get this:  gzip: stdin: not in gzip format tar: Child returned status 1 tar: Error is not recoverable: exiting now   It should start unpacking.  Some people told me not to use the z but I get the same error.  It's a file that I downloaded this way:  wget http://openwall.com/john/f/john-1.7.0.2.tar.gz