I have received an e-mail from "Advances in Engineering". Is it a predatory-platform? Is it reputable?  ...  Dear Dr. XYZ,  We are pleased to inform you that Advances in Engineering selection committee identified your paper “Another XYZ” as a key scientific article contributing to research excellence. We would like to write a feature about your paper and highlight it in our next edition of Advances in engineering news series.  AIE highlight papers of exceptional scientific importance to a broad science and engineering audience (for the latest edition ). The feature is intended to globally disseminate research excellence across academia and in the wider community, and to inspire new research directions.  AIE reaches a global audience of 850,000 professors and scientists per month who seek the key research news and accomplishments in engineering. Papers featured at AIE gain extensive visibility and increased citations.  If you accept our special invitation, our professional writers will write a high quality feature draft about your research paper (significance of the work done) and then share it with you for final approval.  AIE is not-for-profit focused on serving research excellence. However, there is a small nominal fee for featuring key scientific articles at AIE ($75 USD total fee) to cover AIE writers’ time in preparing the feature. We can send you an official invoice and we will feature your research within 14 days.  At AIE, we highlight the researchers work at the cutting edge of science, those who are developing the innovations that will lead to a brighter tomorrow. I look forward to hearing from you.  Respectfully,  ZYX  ZYX, PhD MBA VP Scientific affairs, Advances in Engineering  38 Auriga Drive, Suite 200. Ottawa, ON K2E 8A5, Canada

. While the reasons for his doing this are not yet public, this is a real loss of a valuable service. Does anyone know of similar services available to the general public?  Edit:  is definitely relevant, but that approach is more appropriate for finding top journals rather than identifying bottom ones. I.e., following that method would probably exclude lots of valid, lower-tier journals. Are there any approaches to easily identifying a predatory publisher?


This was a children's or YA novel I read in the 80s or 90s, I think relatively recent at the time.  Written in English. Sent in the present day (as was), a girl is fed up with her life and accepts an offer from a woman to replace her with a robot or clone that will do things like go to school for her. The woman provides a place for the girl to stay when the robot is impersonating her, the place has all her favourite things to eat, which include chocolate eclairs.  Eventually she comes into conflict with the woman and robot trying to get her life back.

I read this book between 1980-82 but it could have been written earlier.  It's about a girl who is dissatisfied with her life, as her parents have her on a diet and she wants to be able to eat what she wants. Someone offers her a solution: to come live in this large building where she can eat all the chocolate eclairs and other junkfood she wants, while a robot doppelganger android version of herself will take her place at home and at school.  The girl agrees, but finds that after week of eating mainly eclairs, she is sick and wants to eat a decent meal. But she is not allowed to eat anything else and has found herself to be a prisoner, so she sets out to get rid of the android and get her life back.   I don't recall the ending but it seemed the 'people' behind it all might have been aliens and the building might have been a kind of ship that then disappears.


So i'm trying to install Ubuntu 14.04 and I can install Ubuntu, but when it restarts with the USB in, it acts like Ubuntu wasn't installed. It goes to the install, try, ect menu. When I take out the USB, after my pc says press ESC to go to boot options, it turns to a black screen with a flashing underscore. I've tried 2 different USB installers now.

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:


What's the difference between , , and ? In general, what's a rule for deciding where to post a question when I have one (which might apply to any of those 3)?  If I'm having a problem with Linux Mint, which seems likely to be the same in Ubuntu, is it appropriate to post it on Ask Ubuntu?

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.


I'm trying to recall a story I read as a child, probably in the late 1980s, though it may well have been written before that. I think it was a short story in an anthology, but I don't remember anything about the book it was in. The plot, as far as I remember, is that a person (probably male) is seeing a counsellor or therapist of some kind, who I'm fairly sure is a robot. The person has been on a space mission that resulted in some other people falling into a black hole while this person escaped, perhaps in an escape pod, and they're trying to deal with the trauma. I remember specifically a scene at the end where the person leaves the therapist's office but then re-enters, finding the room partially reconfigured to match the next client's psychology. The story concludes with the person realising or stating that because of relativistic effects, the people who fell into the black hole are not dead but frozen in time, forever living out the last moments of their lives.

I am looking for a novel that I'd love to re-read it with my wife (my 13-year old self must be proud of me I guess). Key Plot points The plot was about humanity finding an alien station on an orbit of Earth. (I'm not sure if it wasn't Moon itself). On this station there were thousands of ships ready to travel so there rose a company that paid people to get on those ships and explore the galaxy. The problem was humans didn't understand how to steer those ships so they had to rely on preset targets. Of course there was no telling where particular ship was to go and fair amount of them never returned. Chronology and other relevant information I read it as an early teenager back in early 2000s. It was Polish translation of a foreign (possibly English) story. I think (not sure) that the book wasn't new at the time. It was just one of those books you dig out in a library and take to see if it's good. I don't recall cover either and even if I did it'd be of the Polish version. Additional information could be that the narration was led along the psychoanalytics of the main protagonists where he relives his memories from inside the station and his journeys.


I'm reading output from where users put their own input into a latex document. It appears as though the users can include emojis. So my question, what is then minimal needed so that the following MWE will latex without error. Either the emoji is correctly handled or else ignored or even replaced by some box. The important thing for me is that the document latexs without error. \documentclass{article}  \begin{document}      Can this be handled in latex?   👍      \end{document}

I have a web interface that generates LaTeX-letters to customers. These letters are rendered dynamically. Some customers have some special characters in their names, that LaTeX can't translate, so I run into unicode errors all the time. The *.tex-Template includes \usepackage[utf8]{inputenc}, but I keep having problems with unicode characters. Here are two error messages from today: Unicode char \\u8:\xc2\xb0 not set up for use with LaTeX. Unicode char \\u8:\xe5\x8d\x97 not set up for use with LaTeX. For now, I use a Python dictionary to convert some already as problematic identified chars into correct LaTeX code. But it's never ending. Is there a way to tell LaTeX to ignore ALL unicode-related compiling errors, e.g. by telling LaTeX to convert all problematic chars into one ?-char?


For example, use as a font for a book, logo, etc.

I've been looking into using the Ubuntu typeface for a logo.  The logo is for a web site unrelated to ubuntu and open source software.  I'm wondering whether the license allows this, and if so, whether there are any limitations?


I have been reading up on the correct use of 'which' and 'that' but I am still struggling. I am unsure if 'must be taken regularly' is restrictive or not. Both 'which' and 'that' sound correct to me. Can someone please tell me which word is correct to use in the following sentence:  Arava is a strongly recommended medication, which must be taken regularly.   Arava is a strongly recommended medication that must be taken regularly.   Thank you.

When is it appropriate to use that as opposed to which with relative clauses?


What should I use to beat the twins? I used the true nights edge with titanium armour the first time, but after the update I'm using my hollowed armour and the same weapon, but Spazmatizm always kills me in the first minute of the battle.  With the new update, the bosses are harder. What should I do?

In Terraria I often try to defeat spazmatism first, but when he transformed, his flamethrower killed me. What is easiest way to kill The Twins?


I vaguely remember watching an animated movie as a kid where the main protagonists, a man and a woman, are in some kind of a battle.   The thing that I remember the most are these slug like large aliens/insects/monsters that have red orbs all over their body. At some point the woman is wounded/killed and is healed/revied by the creatures. They did this by lifting her up with glowing tentacles.   Here is a crude drawing of the creature:

I can not remember much but I have had this film in my head for years I searched everything I can remember on every website I can think of.  I don't remember the exact story but I'll list everything about it can   Apocalyptic future possibly Two main characters: a boy and a girl riding ostrich-like creatures through a valley An old blind lady that senses things Crashed spaceship looking like a submarine Giant creatures looks like yaks with blue eyes, whose eyes turn red when something is about to happen The old lady says "Some say they went to the stars" while looking at the spaceship The two main characters do something and their eyes turn blue in the distance and the village cheers   This film is at least ten years old and I would appreciate it so much if you knew anything about it, or could help me find the title.


I have been trying to calculate the number of subgroups of the direct cross product $\Bbb{Z}_4 \times \Bbb{Z}_6.$ Using Goursat's Theorem, I can calculate 16. Here's the info:  Goursat's Theorem: Let $G_1 \times G_2$ be a group and let $A/B$ be a subquotient of $G_1$ and $C/D$ be a subquotient of $G_2.$ Also, $\varphi: A/B \to C/D$ is an isomorphism. Then there exists a bijection from the set of all subgroups of $G_1 \times G_2$ and the set of all triples $(A/B, C/D, \varphi)$.  So I counted all the subquotients of $\Bbb{Z}_4$ (there are 6) and all the subquotients of $\Bbb{Z}_6$ (there are 9). There are only 2 isomorphisms. I label them $\varphi_1: \{ 0 \} \to \{ 0 \}$ and $\varphi_2: \Bbb{Z}_2 \to \Bbb{Z}_2$ (because every subquotient is isomorphic to either $\{0\}$ or $\Bbb{Z}_2$). Both of these isomorphisms has only one possible automorphism. So we need only calculate the different combinations of mappings from $A/B$ to $C/D.$  For $\varphi_1,$ there are $3 \times 4 = 12$ possible mappings. For $\varphi_2,$ there are $2 \times 2 = 4$ possible mappings. Thus, there should be a total of 12+4=16 isomorphisms. By Goursat's Theorem, there must be 16 subgroups of $\Bbb{Z}_4 \times \Bbb{Z}_6$.  Only problem is, when I look at every subgroup lattice for $\Bbb{Z}_4 \times \Bbb{Z}_6$, there are only 15 subgroups!  Using my method above (Goursat's Theorem), what am I doing wrong? Or, am I looking at the wrong subgroup lattice (less likely)?  P.S. Let me know if you need more info about my counting methods.

I want to determine      how many subgroups does the additive group $G:=\Bbb Z_{14} \oplus \Bbb Z_{6}$   have?   There are many related posts in our site, for instances:  and . However, it seems that those problems worked with small numbers. I know that $|G|=84=7.2^2.3$ so if $H$ is a subgroup of $G$ then $|H|$ can be taken $12$ possible values as divisors of $84$. Listing all subgroups with given possible orders seems to be not a good choice. Is there any other efficient method to deal with this particular problem? Could it be easier for us if we write $G \simeq \Bbb Z_{2} \oplus \Bbb Z_{2} \oplus\Bbb Z_{3} \oplus \Bbb Z_{7}$?


How can I echo a sql text field into a paragraph?   My code does puts the text in but changes the accents like á to this -> �.  I tried adding UTF-8 in the header and removing it.   Removing UTF-A makes the sql content is ok but all the content outside the paragraph messes up.  I checked the DB was using (UTF-8-unicode), The files were saved with UTF-8  Any ideas on what might be wrong?  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />  <textarea class="texto" name="textoarticulo"  id="textoarticulo" form="formarticulo" placeholder="Texto del art&iacute;culo...">  <?     echo $row['txt4'];   ?> </textarea>

I'm setting up a new server and want to support UTF-8 fully in my web application. I have tried this in the past on existing servers and always seem to end up having to fall back to ISO-8859-1.  Where exactly do I need to set the encoding/charsets? I'm aware that I need to configure Apache, MySQL, and PHP to do this — is there some standard checklist I can follow, or perhaps troubleshoot where the mismatches occur?  This is for a new Linux server, running MySQL 5, PHP, 5 and Apache 2.


A new mechanic in Mario kart 8 is the hang gliders, which allow you to steer your character in the air after a big jump. For maximum speed, should I try to maximize air time, by aiming upwards or minimize air time by aiming downwards? Or is it faster to do neither, and stay level vertically?

There are some sections of tracks that allow you to deploy your hang glider or parachute.  This allows you to glide in relative safety until you hit the track again.  But you can also hit forward or back on the control stick to tilt down or up, respectively.  Is there an advantage to staying in the air?  Or does heading back down towards the track give you more speed than just gliding along?


I am bit of a batch file noob, so I'd really appreciate your help. I have a ton of files stored in a single directory which I wish to sort into subfolders based on the first word in their filenames. So, I have files like these:  C:\Folder\ABC-001 C:\Folder\ABC-002 C:\Folder\EFG-001 C:\Folder\HIJ-002   And I wish to move all files to subfolders based on the first word, ending up like this:  C:\Folder\ABC\ABC-001 C:\Folder\ABC\ABC-002 C:\Folder\EFG\EFG-001 C:\Folder\HIJ\HIJ-002   Please help me get out here. Thank a lot !

I am bit of a batch file noob, so I'd really appreciate your help. I have a ton of files stored in a single directory which I wish to sort into subfolders based on the first word in their filenames. So, I have files like these:  C:\Folder\Wedding2018 img20929.jpg  C:\Folder\Wedding2018 entrance.mov C:\Folder\Wedding2018 registry of guests.pdf  C:\Folder\HorseRiding2017 spirit1.jpg C:\Folder\HorseRiding2017 guests.txt  C:\Folder\HorseRiding2017 certificate.pdf C:\Folder\HorseRiding2017 jumping.mov   And I wish to move all files to subfolders based on the first word, ending up like this:  C:\Folder\Wedding2018\img20929.jpg C:\Folder\Wedding2018\entrance.mov C:\Folder\Wedding2018\registry of guests.pdf  C:\Folder\HorseRiding2017\spirit1.jpg C:\Folder\HorseRiding2017\guests.txt C:\Folder\HorseRiding2017\certificate.pdf C:\Folder\HorseRiding2017\jumping.mov   I've found a couple of scripts that almost do what I need, but I don't have the chops to bring it home:       I just can't work out how to integrate the script to grab the first word and make a directory to which the files will be moved.  Can you help me get this across the line?


How can I determine the collection date for ArcMap's base map with imagery? I'm using ArcMap 10.3.1

It seems like it was possible to do this with Google Imagery if I recall but is there any way to determine the date of collection of Esri's World Imagery basemap (or other basemaps) at a given location?   Something I read indicated that this was updated Sept, 2014 but I don't think that has anything to do with the date of collection.     I have been telling people that it is 2014 Imagery but I've been challenged on that statement because features on the landscape are showing up that have reportedly been removed.     The basemap I'm most interested in knowing about is .


Let $a$ be an element in a group $G$. What is a generator for the subgroup $H = G_1 \cap G_2$ where $G_1, G_2$ are the groups generated by $a^m, a^n$, respectively?  Please can someone check my proof that I posted below?    I had actually already solved the question! I was just wondering if anybody could write out a fully rigorous proof so I can check if mine works. Basically, the problem is easy if the order of $a$ is infinite, but in the case where the order of $a$ is finite, a bit more care needs to be taken.  Anyway, here's how I did it:  We will prove that $⟨a^{lcm(m,n)}⟩ = H$.  Firstly, note that $a^{lcm(m,n)} \in G_1, G_2$ so $⟨a^{lcm(m,n)}⟩ \subseteq H$.  Now assume $a^k \in H$. If $a$ has infinite order, $m|k$ and $n|k$, implying that $lcm(m,n)|k$, so $a^k \in ⟨a^{lcm(m,n)}⟩$. If $a$ has finite order, say $r$, then there exists an integer $x$ such that $r|k-mx$ as $a^k \in G_1$. Thus $gcd(m,r) | k$. Similarly $gcd(n,r) | k$. So $lcm(gcd(m,r), gcd(n,r))|k$. It is not hard to show that this big lcm expression equals $gcd(lcm(m,n), r)$, so $gcd(lcm(m,n), r) | k$. Now let $lcm(m,n)=dp, r=dq$ for coprime $p,q$. Then $d|k$ so write $k=de$ for an integer $e$.   We would like to find an integer $s$ such that $r|k-slcm(m,n)$, but this is equivalent to $dq|de-sdp$ iff $q|e-sp$, and such $s$ can be found as $p,q$ are coprime!  Hence $a^k \in ⟨a^{lcm(m,n)}⟩$ and we are done.  Please let me know whether or not this proof is correct, and have I complicated things?

So I want to show that $\langle a^m \rangle \cap \langle a^n \rangle = \langle a^{\operatorname{lcm}(m, n)}\rangle$. My approach to this problem was to show a double containment, i.e. to show that $\langle a^m \rangle \cap \langle a^n \rangle \subseteq  \langle a^{\operatorname{lcm}(m, n)}\rangle$ and $ \langle a^{\operatorname{lcm}(m, n)}\rangle \subseteq \langle a^m \rangle \cap \langle a^n \rangle$.  I would like to see a full proof for this, specifically $\langle a^m \rangle \cap \langle a^n \rangle \subseteq \langle a^{\operatorname{lcm}(m, n)}\rangle$. (I tried it with the approach of breaking it down into to cases; $a$ has infinite order and $a$ has finite order, the latter of which i would appreciate the most help on.)  My approach to solving the whole problem: (I would appreciate any feedback on anything that is wrong, or a different approach to the proof.)  To show the easier containment, $\langle a^{\operatorname{lcm}(m, n)}\rangle \subseteq \langle a^m \rangle \cap \langle a^n \rangle$, I did the following:  Let $l = \operatorname{lcm}(m, n)$. Let $j \in \langle a^l\rangle$, so $j = (a^l)^k = a^{lk}$ for some $k \in \mathbb Z$. Since $l$ is a multiple of $m$ and $n$ by definition, we can say $l = ms = nt$ for some $s, t \in \mathbb Z$. Now $j = a^{kl} = a^{kms} = (a^m)^{ks} \in \langle a^m\rangle$. Similarly, $j = a^{kl} = a^{knt} = (a^n)^{kt} \in \langle a^n\rangle$. Now, since $j \in \langle a^m\rangle$ and $j \in \langle a^n\rangle$, it follows that $j \in \langle a^m \rangle \cap \langle a^n \rangle$. Thus, by definition, $\langle a^{\operatorname{lcm}(m, n)}\rangle \subseteq \langle a^m \rangle \cap \langle a^n \rangle$.  For the second containment, the one which I'm having more problems with, I attempted the following:  Case in which $a$ is infinite: Suppose that $\vert a \vert = \infty$. Let $c \in \langle a^m \rangle \cap \langle a^n \rangle$. Then $c = a^{mx} = a^{ny}$ where $x, y \in \mathbb Z$. It follows that $a^{mx - ny} = e$ and so $mx = ny$ because if $mx  > ny$ then the difference would not be zero, and we would have an element that was finite, contradicting our hypothesis. And since $mx = ny$ we know $\operatorname{lcm}(mx, ny) = mx = ny$ and $\operatorname{lcm}(mx, ny)$ is a multiple of $\operatorname{lcm}(m, n)$. Hence $c \in \langle a^{\operatorname{lcm}(m, n)}\rangle$ and thus $\langle a^m \rangle \cap \langle a^n \rangle \subseteq  \langle a^{\operatorname{lcm}(m, n)}\rangle$.  Case in which $a$ is finite: I tried starting it out the same as the previous case, but i could never reach my conclusion :(


There's a lot of good animations and games on Newgrounds and many other sites. They all used touse Flash player, too. Unfortunately, Flash has been discontinued on the last day of 2020. However, the Newgrounds player that replaced Flash player on Newgrounds apparently doesn't work on all games because they haven't been converted from Flash yet. Also, other sites still haven't got the message and still use Flash. Any ideas on any workarounds to still access these games/animations? If anybody has asked this question before, please link me to the dupe. By the way, I am using Windows 10 and I either use FireFox or Chrome as my main browsers, so any solutions using them would be preferred. RIP Flash

I would like to use Flash Player to show web contents but since today (12 Jan 2021) Adobe is blocking it. Is there a way to use it? I've tried Firefox, Chrome, Safari and Brave browsers.


I want to develop iOS application with swift in windows 8.  Is it possible?  Thanks in advance for helping.

Is there any way to tinker with the iPhone SDK on a Windows machine? Are there plans for an iPhone SDK version for Windows?  The only other way I can think of doing this is to run a Mac VM image on a VMWare server running on Windows, although I'm not too sure how legal this is.


How to proof /P(A)/=2ⁿ / / For modulus sign A: Given set P(A):Power of set A 2ⁿ: The number of possible elements. Hints: In the question it says that to prove it by induction method .  /P(A)/=2ⁿ is possible when set A has 'n' number of elements.

Theorem. Let $X$ denote an arbitrary set such that $|X|=n$. Then $|\mathcal P(X)|=2^n$.      Proof. The proof is by induction on the numbers of elements of $X$.      For the base case, suppose $|X|=0$. Clearly, $X=\emptyset$. But the empty set is the only subset of itself, so $|\mathcal P(X)|=1=2^0$.      Now the induction step. Suppose $|X|=n$; by the induction hypotesis, we know that $|\mathcal P(X)|=2^n$. Let $Y$ be a set with $n+1$ elements, namely $Y=X\cup\{a\}$. There are two kinds of subsets of $Y$: those that include $a$ and those that don't. The first are exactly the subsets of $X$, and there are $2^n$ of them. The latter are sets of the form $Z\cup\{a\}$, where $Z\in\mathcal P(X)$; since there are $2^n$ possible choices for $Z$, there must be exactly $2^n$ subsets of $Y$ of which $a$ is an element. Therefore $|\mathcal P(Y)|=2^n+2^n=2^{n+1}$. $\square$      From the above explanation, I don't understand why the set that contains $\{a\}$ will contain $2^{|n|}$ elements when it should clearly be $2^{|1|}$.  The construction of a new set $S$ is the union of the old set with cardinality $n$ and an new element $\{a\}$, therefore the set that do not contain $\{a\}$ still has cardinality $n$ and the set that contains $\{a\}$ is just $\{a\}$, one element...  Can someone please elucidate?


If $a, b, c$ are distinct positive real numbers such that $abc=1$, prove that   $$\frac{a^3}{(a-b)(a-c)} + \frac{b^3}{(b-a)(b-c)} + \frac{c^3}{(c-b)(c-a)} ≥ 3.$$  I tried to do this problem by assuming that $a<b<c$. By using this, the first and the third term of the inequality are positive and the second is negative. Thus, we can obtain the minimum value of the expression by minimizing the sum of the first and the third and maximizing the second. I'm stuck at this part and would appreciate if someone could help me.

let $p,q$ is a  $$(x-a)(x-b)+(x-b)(x-c)+(x-c)(x-a)=0$$ roots,find this value $$\dfrac{a^3}{(a-p)(a-q)}+\dfrac{b^3}{(b-p)(b-q)}+\dfrac{c^3}{(c-p)(c-q)}$$ where $a,b,c$ is give numbers.  I know this  Lagrange interpolation $$\dfrac{a^3}{(a-b)(a-c)}+\dfrac{b^3}{(b-a)(b-c)}+\dfrac{c^3}{(c-a)(c-b)}=a+b+c$$  But my problem is different.so how find it?


This is a very hard functional equation.  the problem is this :  find all functions $ f : \mathbb{R} \rightarrow \mathbb{R} $ such that : $ f(f(x))=x^2-2 $  to solve it i have no idea! can we solve it with highschool olympiad education?  please help : )

Find all $f(x)$ satisfying $f(f(x)) = x^2 - 2$.   Presumably $f(x)$ is supposed to be a function from $\mathbb R$ to $\mathbb R$ with no further restrictions (we don't assume continuity, etc), but the text of the problem does not specify further.   Possibly Helpful Links: Information on similar problems can be found  and .  Source:  It is about to be closed for containing too many problems in one question. I'm posting each problem separately.


I am trying to solve the following question.  Let R be a PID. Suppose that 2 is a unit in R. Let $c_1, ..., c_t$ be irreducible elements of R and let $c=c_1 ... c_t$. Show that the ring $R[x]/(x^2-c)$ is a Dedekind domain.  A Dedekind domain is a noetherian ring of dimension 1, which is integrally closed. So far I have that R is a PID $\Rightarrow$ R is a Dedekind domain, so in particular $\dim(R)=1$. Also R noetherian $\Rightarrow$ $\dim(R[x]) = 2$ and $R[x]$ noetherian. $R[x]$ noetherian $\Rightarrow$ $R[x]/(x^2-c)$ noetherian. I think I'm supposed to somehow use the fact that we are taking the quotient by an irreducible polynomial to show that the dimension is reduced by 1, but I'm not quite sure how. Also I'm not sure how to use the assumption that 2 is a unit, nor how to go about showing that the resulting ring is integrally closed.

A problem on an algebra qual reads     Show that the ring $R = \mathbb{C}[x,y]/(y^2 - x^3 +1)$ is a Dedekind   domain. (Hint: compare $R$ with the subring $\mathbb{C}[x]$.)   $R$ is clearly Noetherian. It is an integral extension of $\mathbb{C}[x]$, so inherits its dimension, which is one. How do I know it is normal?


There are a few questions I've asked which took much longer time to get a proper solution. But I can no longer use/test those solutions due to different reasons. So those questions remain unsolved. Is it possible for the community to take over those questions so that if any one encountering the same issue can test the suggested solutions and accept the working solution.

Let's say I have a problem, and post a question on StackOverflow.  I don't get any good answers, so I end up writing my own buggy implementation, or shelving the feature entirely.  Months later, someone provides an answer.  It looks promising and gets a few upvotes, but by this point it is too late to rip out the old implementation, or I have left the job, etc.  The question is no longer relevant to me.  Do I have a responsibility as the original poster to see if this answer would have solved my problem?  Relatedly, if someone pesters me about my accept rate, is "I no longer have the ability to check if any of these answers are right" an acceptable response?


How do I find out what fields are required when I create a record in Salesforce using SOQL?

I want to know how I tell whether a field is required or not in an Apex controller.   In my controller I get the record id and then get the object of that record by a describe call, then I get all the fields of that object, but I am not able to tell which field is required and which is not.


I am running some javascript code in on page but I don't want it running when I try and edit the page. How can I stop this from running in edit page and only when the page has been published

Is there a way to find out if a page is in Edit Mode from JavaScript?  I know server-side can be found using SPContext.Current.FormContext.FormMode but I can't find any means of doing it from JavaScript.


Two cylinders of radii r1, and r2 having moments of inertia I1, and I2, about their respective axes. Initially, the cylinders rotate about their axes with angular speeds w1, and w2 as shown in the figure. The cylinders are moved closer to touch each other keeping the axes parallel. The cylinders first slip over each other at the contact but the slipping finally ceases due to the friction between them. Find the angular speeds of the cylinders after the slipping ceases.   I applied conservation of momentum here but I'm unable to obtain the right answer. Taking both cylinders as system, since only friction acts and these forces contribute to internal torques so with absence of external torques I conserved angular momentum of the system but the answer is incorrect.  My question is why cant we conserve angular momentum in such a scenario? How is there external torque and what forces are providing the external torque?

Exercise:  A disk of radius $R$ and moment of inertia $I_1$ rotates with angular velocity $\omega_0$. The axis of a second disk, of radius $r$ and moment of inertia $I_2$ is at rest. The axes of the two disks are parallel. The disks are moved together so that they touch. After some initial slipping the two disks rotate together. Find the final rate of rotation of the smaller disk.    Attempt: $L_{1_0} = L_1 + L_2 \rightarrow I_1\omega_0 = I_1\omega_1 + I_2\omega_2$ $\omega = \frac{v}{r} \rightarrow v = \omega r$ $\omega_1 R = \omega_2 r \rightarrow \omega_1 = \frac{r}{R}\omega_2$ $I_1\omega_0 = I_1\frac{r}{R}\omega_2 + I_2\omega_2 \rightarrow \omega_2 = \frac{I_1\omega_0}{\frac{r}{R}I_1 + I_2}$ $$\omega_2 = \frac{I_1\omega_0}{\frac{r}{R}I_1 + I_2}$$  Request: Is my solution correct? If not, where and why?


I'm setting up a new laptop that has Windows 8.1 installed. What I'd like to do: require the account password to be entered whenever I get an elevate prompt ("Allow the following program to make changes to your system?").  My main use case is that I want to let my kids use my laptop, but ensure that they can't install programs or change settings. I know I could give them a separate login with lower permissions, but I'd rather just have one login.

I am one of the very few who likes the security of UAC and so I have the UAC set to "Always Notify" on my Admin account. But I would be even happier if the system would prompt me for a password, when notifying me.  I can get what I want by adding a second non-admin user and using that account.  But somehow it seems wasteful to have two accounts set up when I will always use the non-admin account day-to-day.  So I am wondering if there is any setting that would cause an Admin account to behave password-prompting-wise as a standard account?


How can i print all the values from the following hashmap  ServletContext appScope = request.getServletContext();         Map<String, List<String>> onLine = (HashMap<String, List<String>>)appScope.getAttribute("User");         if(onLine != null) {             out.print(onLine.get("1"));         }

If I have an object implementing the Map interface in Java and I wish to iterate over every pair contained within it,  what is the most efficient way of going through the map?  Will the ordering of elements depend on the specific map implementation that I have for the interface?


I am writing a test case which I consider handling exception in it. I wrote it this way.  @Test public void myTest() {     int result = mymethod(a + b);     try{         assertEquals(1, result);     }catch(Exception e){         throw new RuntimeException();     }  }   Is this the write way? I am a little bit confused as I have not done this before.

How can I use JUnit4 idiomatically to test that some code throws an exception?  While I can certainly do something like this:  @Test public void testFooThrowsIndexOutOfBoundsException() {   boolean thrown = false;    try {     foo.doStuff();   } catch (IndexOutOfBoundsException e) {     thrown = true;   }    assertTrue(thrown); }   I recall that there is an annotation or an Assert.xyz or something that is far less kludgy and far more in-the-spirit of JUnit for these sorts of situations.


I am trying to get the location of the user from location api of android. I have written following lines of code to get the latitude and longitude and then send the data to some other activity via Intent.  LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);      locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 1000, 10f, this);      Criteria criteria = new Criteria();      String provider = locationManager.getBestProvider(criteria, true);       location = locationManager.getLastKnownLocation(provider);      try{         latitude = location.getLatitude();          longitude = location.getLongitude();          LatLng latLng = new LatLng(latitude, longitude);          myPosition = new LatLng(latitude, longitude);         mMap.addMarker(new MarkerOptions().position(myPosition));     }catch (NullPointerException e){         e.printStackTrace();     }   But I got 1 error, when I run on android 5+ device I get Null pointer Exception on each line from getting latitude variable. But for other android sdks Null pointer exception does not appear also.   And also the marker is not visible So I think this is the where NPE comes into picture. But I don't know why android 5+ gives this behaviour. I have compiled this app using android 6.  So for this purpose I have written code in try catch block and added NPE.  Why this is causing error? I am not able to figure it out. Thanks in advance!!

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?


In linear regression squared error function is calculated as:  $$ Error(w) = \sum_{i=0}^{m} W^{T}x_i - y_i $$   In which $W^T$ means the transpose of weights vector. $x_i$ is the ith input in vector x and $y_i$ is the ith desired output.   We can write it in matrix form as follows:  $$ (Xw - y)^T (Xw-y) $$  My question is that according to what matrix algebra rules or sequence of manipulation, the summation can change into the above matrix form? Please let me know if there is any resource that I can learn the corresponding matrix algebra?  Any help is appreciated.

This question regards the problem of . Vectors and matrices will be denoted in bold.  Premises. Let $N,K$ be given integers, with $K \gg N > 1$. The transpose of matrix $\mathbf{A}$ will be denoted with $\mathbf{A}^T$. Suppose the following statistical model holds $$ (*) \quad \mathbf{y} = \mathbf{Hx + n}, \quad \mathbf{n} \sim \mathcal{N}_{K}(\mathbf{0}, \mathbf{C})  $$ where $\mathbf{y} \in \mathbb{R}^{K \times 1}$ are the observables, $\mathbf{H} \in \mathbb{R}^{K \times N}$ is a known full-rank matrix, $\mathbf{x} \in \mathbb{R}^{N \times 1}$ is a deterministic vector of unknown parameters (which we want to estimate) and finally $\mathbf{n} \in \mathbb{R}^{K \times 1}$ is a disturbance vector (noise) with a known (positive definite) covariance matrix $\mathbf{C} \in \mathbb{R}^{K \times K}$. The  (ML) estimate of $\mathbf{x}$, denoted with $\hat{\mathbf{x}}_{ML}$, is given by $$ (1) \quad \hat{\mathbf{x}}_{ML} = (\mathbf{H}^T \mathbf{C^{-1}} \mathbf{H})^{-1} \mathbf{H}^T \mathbf{C}^{-1} \mathbf{y} $$ and this is also the standard formula of Generalized Linear Least Squares (GLLS). Consider the standard formula of Ordinary Least Squares (OLS) for a linear model, i.e. $$ (2) \quad \hat{\mathbf{x}}_{OLS} = (\mathbf{H}^T \mathbf{H})^{-1} \mathbf{H}^T \mathbf{y} $$ As a final note on notation, $\mathbf{I}_K$ is the $K \times K$ identity matrix and $\mathbf{O}$ is a matrix of all zeros (with appropriate dimensions). Now, for the problem at hand, assume that $\mathbf{C}^{-1} = \mathbf{I}_K + \mathbf{X}$, where $\mathbf{X} \in \mathbb{R}^{K \times K}$ is a symmetric, invertible matrix (and, for the formalism to make sense, $\mathbf{X}$ is such that $\mathbf{I}_K + \mathbf{X}$ is invertible and the inverse is positive definite). In this case, it can be proven (using matrix inversion lemma) that $$ (3) \quad (\mathbf{H}^T \mathbf{C^{-1}} \mathbf{H})^{-1} \mathbf{H}^T \mathbf{C}^{-1} = (\mathbf{H}^T \mathbf{H})^{-1} \mathbf{H}^T + \mathbf{Q} $$ where the expression for the matrix $\mathbf{Q} \in \mathbb{R}^{N \times K}$ can be found (I will omit it here). Now, finally,  Proposition 1. If $\mathbf{H}^T\mathbf{X} = \mathbf{O}_{N,K}$, then equation $(1)$ degenerates in equation $(2)$, i.e., there exists no difference between GLLS and OLS.  The proof is straigthforward and is valid even if $\mathbf{X}$ is singular. Now, my question is  Question: Can an equation similar to eq. $(3)$ (which "separates" an OLS-term from a second term) be written when $\mathbf{X}$ is a singular matrix?  I am not interested in a closed-form of $\mathbf{Q}$ when $\mathbf{X}$ is singular. But I do am interested in understanding the concept beyond that expression: what is the actual role of $\mathbf{Q}$? In which space does it operate?  I found this problem during a numerical implementation where both OLS and GLLS performed roughly the same (the actual model is $(*)$), and I cannot understand why OLS is not strictly sub-optimal. I found this slightly counter-intuitive, since you know a lot more in GLLS (you know $\mathbf{C}$ and make full use of it, why OLS does not), but this is somehow "useless" if some conditions are met. What are these conditions?  As a final note, I am rather new to the world of Least Squares, since I generally work within a ML-framework (or MMSE in other cases) and never studied the deep aspects of GLLS vs OLS, since, in my case, they are just intermediate steps during the derivation of MLE for a given problem.  If the question is, in your opinion, a bit too broad, or if there is something I am missing, could you please point me in the right direction by giving me references? Preferably well-known books written in standard notation.


Which of the following is right?  I am reading a paper (math) where it says:  Demanding that A is a Lorentz scalar, ...  But I feel like it should be  Demanding that A be a Lorentz scalar, ...  I'd be grateful for help and would appreciate if someone could point out what kind of grammatical construction this actually is.

We will make the convention that exact categories be skeletally small.   Is this construction (used in a mathematical context) correct? There is something that strikes me as odd in that "be". Should it be "are"? I know I've seen a similar way of using "be" like that, without conjugating the verb, but I'm not completely sure when it should be used.


So I just watched Enders Game, great flick, but I'm a little confused. They talk in the movie about how Ender had two older siblings that had the same genius as Ender, but flunked out of the program because one was too passive, and the other (Peter) was way too aggressive. Ender was the balance between the two. At the end of the movie, Ender wins the war by completely annihilating the bugs home planet. How could Peter have been considered too violent to commit a total genocide of a species?  In the end Ender was left a broken little child because he was fooled into killing an entire species, and probably never would have done what he did if he'd known that the "simulation" were the real thing. Peter on the other hand, could have probably done the same job, knowingly eradicated the entire homeworld of their enemy, and come out at the end unaffected.   If the end result was the brutal slaughter of an entire race, then why was Peter considered "too aggressive" for the job?

Why didn't the IF want Peter Wiggin?  Ender's Game implies that they didn't want him for being too violent/aggressive (I believe the quote from Graff was something like "doesn't know half the time if he wants to be a human or a jackal").  But this seems to be contradicted by two facts:   They already have specimens like that in school. Bonzo Madrid, for one, is the same except dumber.  Or Bernard, of who Alai said "I'm not Bernard, I never tortured cats for fun.". If you recall, the main signal that Peter was dangerous was his torturing small animals. Less importantly, Peter turned out way non-jackaly. We can write that off on faulty analysis during early years.   I'd prefer answers based on book sources or Card's statements if any are available. Please don't quote Graf's original statement from beginning of Ender's game as an answer - that's what I'm questioning.   IMPORTANT: Any answers that cite Peter as being a possible impediment to Ender should take into account the fact that Peter was rejected before Ender was even authorized to be born.    P.S. Just to clarify - I didn't ask why IF didn't think Peter Wigging was as genius of a commander as Ender. I am asking why he wasn't taken to the School like all the other talented bullies were. They took plenty of other kids who weren't Ender, so why wasn't Peter among them?


I have made a mailsender in C#.but the program does a error when I run it.  this is my code:  MailMessage mail=new MailMessage("shahidi83am@gmail.com","shahidi83am@yahoo.com","subject","this is a test");         SmtpClient smtp =new SmtpClient("smtp.gmail.com");         smtp.Port=587;         smtp.Credentials= new System.Net.NetworkCredential("username","pass");         smtp.Send(mail);   and this is the error:     System.Net.Mail.SmtpException: The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.0 Must issue a STARTTLS command first. 79sm6578238wrc.34 - gsmtp

Instead of relying on my host to send an email, I was thinking of sending the email messages using my Gmail account. The emails are personalized emails to the bands I play on my show.   Is it possible to do it?


I've been having a fairly critical issue that I've yet to resolve. It may be that I need to take this to launchpad but if ANYONE has info at all, please help.  explains the problem. If you have good experience with this OS or other knowledge that pertains, please take a look at that link and reply. I need help here as this is above my head.  Thanks in advance for your time.  [listen, forget the badges for a sec and let this through. I need help here and the prior post has 0 replies and likely will stay that way.]

After running a VM and logging out, I got a black screen. I powered off and re-started but got the same after the bios option in start up passed. Several attempts went bye with the same result. So I fiddled with bios boot options a bit and was able to get to a different looking Ubuntu start up screen which, after entering pass key would run a series of commands that were too numerous and frantic to make out. They appeared to be overlapped/layered (the text that is) and seemingly repeating endlessly. I had to power down to get it to stop and re-booting just had the same effect. Finally, I hit the down arrow key when prompted for "disk sda5_crypt" at the pseudo Ubuntu log-in screen I mentioned before. This brought me to an all black screen which read something like:  lvmetad not active cannot process volume group "umbuntu-vg" unlock disk sda5_crypt**   From here I entered a password and Ubuntu start up ran.  That was an unsettling hour or so and I'd like to avoid that in the future. Any ideas what caused it and how to avoid it going forward?  Should have said this before but Ubuntu is the only OS on my machine and my optical drive cannot be opened manually.


I have Lubuntu 16.10 and I want to clean my usb sticks of Windows viruses but I can't do it. When i try to delete some .exe files they duplicate themselves like program.1 and program.1.1  and so on. There is no error messages.  What's the solution to this?

In Windows there is a straightforward "Format" option in a flash drive's right-click pop-up menu. Where's that in Ubuntu?


Why did George Lucas (or whoever else) decide to call Order 66... well, Order 66?  I'm specifically looking for an out-of-universe answer. I already know that the in-universe answer is, "It came after Order 65, and before Order 67."

From what I've found, there were something like 150 contingency orders to help hide the Palpatine's Order 66 and what it was meant to do.  The first time I saw Revenge of the Sith, I thought he gave the order "666", and I thought, cute, the devil, but then I learned it was actually "66". Does it mean anything?  Is it still referencing the devil?  Is it just a number pulled from a hat? In short, what is the significance of the number in Palpatine's infamous line:     Execute Order 66   Update: George Lucas also did "American Graffiti" which references Route 66, but I don't how to connect that with killing Jedi.  Jedi road kill?


I'm getting coordinates via an API that works most of the time (giving me a String with a double, example : "53.2") but sometimes i see in the javascript console that I receive 'undefined' instead of let's say 53.2. I tried to check if what i receive is undefined but it doesn't work and I keep getting this type of error sometimes:     "java.lang.NumberFormatException: For input string: "undefined" "  Could you help me please? I'd like to know if I have to check with another condition, maybe null or something else..  EDIT: My main concern is more to know when i get undefined value in the Java servlet and less to make the Javascript work better. Thank you!      //JAVA CODE IN THE SERVLET     String fromlong = request.getParameter("fromlong");    //COORDINATES     String fromlat = request.getParameter("fromlat");     String tolong = request.getParameter("tolong");     String tolat = request.getParameter("tolat");      if(fromlat == "undefined") {         fromlat = "50.0";     }     if(fromlong == "undefined") {         fromlong = "50.0";     }     if(tolat == "undefined") {         tolat = "50.0";     }     if(fromlat == "undefined") {         tolong = "50.0";     }      //Then there is a function that uses these values   and that's the javascript code where i get the values with an api then send them with a hidden input (this works when the api sends me a correct value most of the time then i'd like to check if what i got in the servlet is correct before using it)  getCoordinates1(from);  function getCoordinates1(database){     $.ajax({         url: 'http://api.positionstack.com/v1/forward',         data: {           access_key: 'MYKEY',           query: database,           limit: 1         }       }).done(function(data) {             var mylatitude = data.data[0].latitude;             var mylongitude = data.data[0].longitude;              document.getElementById('fromlat').value = mylatitude;             document.getElementById('fromlong').value = mylongitude;              console.log(data.data[0].latitude);             console.log(data.data[0].longitude);       });     }          and at the end of the page i send this with an hidden input  <input type="hidden" id="fromlat" name="fromlat" value="" />

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 was not happy with the answer to this question so I am posting it again with my own answer to

I've been using the beta iCloud Photo Library for a week and a bunch of photos got duplicated and I'd like to wipe all the photos out and start over.  I have backups of all the photos and have turned off iPhoto Cloud Library on all iOS devices. When I log into the web app - it still shows dozens of albums and I can delete all the photos, then go to deleted items and then purge them, but the ghost albums are still there messing things up.  I've turned off the library entirely and you can see there is a 30 day waiting period.     If I click on albums, there are pages of them and no delete button anywhere. If I turn on the library on an iOS device, data starts flooding back as if I wanted to recover the photos.  I don't want to recover anything, I want a clean wipe and clean slate.  Currently, there are 7807 photos in the deleted album and no way to mass delete them. I have 31 albums that show up in iCloud and no way to delete them.  Is there some way to accelerate this or must people wait a month for a corrupt library to eventually be purged to start over?  (I have tickets open with AppleCare after  and it's escalated to engineering, but I was informed that it might be a week or two before it gets seen :-( Perhaps someone has a better idea to clear things out or noticed something I've missed.)


When to use 'of' with 'a couple' and when not to? Like we say 'I ate a couple of bananas today' and 'Give me a couple more minutes'. So is there any specific rule which we have to keep in mind?  Thank you!

I would write a couple of . I often read/hear a couple .  I assumed this was an American English thing (I'm British), and just a convenient shortening of the phrase for speaking. It's easier to say a couple minutes vs a couple of minutes.  On a side note, this doesn't seem to restrict the number of things to two, but just a small amount–less than a few, in my mind.


My BLU Studio 5.5 won't allow me to install anymore apps. I have a 18G SD card installed. When accepting to install it says "Error downloading phone had insufficient space". What do I do to install more apps.?

After one of the latest updates (not sure if it was the last one or a previous one) of the Google Play app, I am having an error trying to update a large app (42MB). It says:     Error Downloading . There is insufficient space on the device.   My device is a Samsung P1000 running Froyo. It's rooted, but the error was there before rooting it.  A quick Google search showed several Samsung users having the same problem (the app in question that was giving me the headache is Smurf's village). Some said that removing the updates to the Android Market (Google Play) app would fix it, but to me it was of no avail.  I also tried the procedure in  to no avail.  Now I am stuck with a prehistoric version of the Market (that works on small apps) and still cannot update Smurf's Village or install big apps. How can I fix this?  EDIT: device has over 2GB of internal SD storage, 27GB of external SD card, so space is not an issue.


Problem: Underscores in my citation file causes the error "missing $ inserted"  Issue: I need to keep those underscores (there are too many of them) because they link to the IEEEabrv file which replaces these codes with the abbreviated journal name etc....  Question: Do you have a solution that lets me keep tags like "IEEE_J_JLT" and have latex recognize that this, text mode, is different than the math mode without having to edit all of the instances and replacing _ with \ _ (backslash underscore)?  Example bib file entry:  article{test:2013,     Author = {Test, D. and Tesssst, J.},     Journal = {IEEE_J_JLT},     Month = {April},     }

I am using the following syntax, with no errors or warnings. However, the journal names are still not abbreviated. I compiled the file numerous times, as well as the bibliography. Everything compiles with no errors.  The syntax:   \bibliographystyle{IEEEtran} \bibliography{IEEEabrv,references}   Additional info: I am using BibDesk and TeXStudio on a macbook.  Do you have any idea what might be the issue? and how to solve it? Thank you.  Edit:  Example entry from the IEEEabrv file:  @STRING{IEEE\_M\_COM        = "{IEEE} Commun. Mag."}   Example entry from my references file:  @article{dai:2015,     Author = {Test, T.},     Journal = {IEEE\_M\_COM },     Month = {September}     }


I've no idea why this script sends email into the spam folder. I tried to fix it using SMTP but it was useless, it only works using Hotmail.  I'm using MAMP for local hosting because my work is not online yet.  Why? How can I fix this problem?  Script:   <?php  require("PHPMailer.php"); session_cache_limiter( 'nocache' ); header( 'Expires: ' . gmdate( 'r', 0 ) ); header( 'Content-type: application/json' );   $to         = 'myEmail';  // put your email here  $email_template = 'simple.html';  $subject    = strip_tags($_POST['subject']); $email       = strip_tags($_POST['email']); $name       = strip_tags($_POST['name']); $message    = nl2br( htmlspecialchars($_POST['message'], ENT_QUOTES) ); $result     = array();    $mail = new PHPMailer();  $mail->IsSMTP();    $mail->Host = "smtp.gmail.com";  $mail->SMTPAuth = true;  $mail->SMTPSecure = 'ssl';  $mail->Port = 465;   // gmail account data  $mail->Username = "myAccountGmail";  $mail->Password = "myPasswordGmail";   if(empty($name)){      $result = array( 'response' => 'error', 'empty'=>'name',    'message'=>'Error!&nbsp; Name is empty.' );     echo json_encode($result );     die; }   if(empty($email)){      $result = array( 'response' => 'error', 'empty'=>'email', 'message'=>'Error!&nbsp; Email is empty.' );     echo json_encode($result );     die; }   if(empty($message)){       $result = array( 'response' => 'error', 'empty'=>'message', 'message'=>'Error!&nbsp; Message body is empty.' );      echo json_encode($result );      die; }    $headers  = "From: " . $name . ' <' . $email . '>' . "\r\n"; $headers .= "Reply-To: ". $email . "\r\n"; $headers .= "MIME-Version: 1.0\r\n"; $headers .= "Content-Type: text/html; charset=UTF-8\r\n";   $templateTags =  array(     '{{subject}}' => $subject,     '{{email}}'=>$email,     '{{message}}'=>$message,     '{{name}}'=>$name,     '{{phone}}'=>$phone     );   $templateContents = file_get_contents( dirname(__FILE__) . '/email-templates/'.$email_template);  $contents =  strtr($templateContents, $templateTags);  if ( mail( $to, $subject, $contents, $headers ) ) {     $result = array( 'response' => 'success', 'message'=>'Thank You!&nbsp; Your email has been delivered.' ); } else {     $result = array( 'response' => 'error', 'message'=>'Error!&nbsp; Cann\'t Send Mail.'  ); }  echo json_encode( $result );  die;

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.


I am looking for a fantastic movie from the 70's, or 80's, maybe early 90's.  Various groups are sent on a search for an artifact; I think it was a sword. There is one scene I can remember quite clear: A group of riders is stopped by some kind of lizardmen coming out of the ground in front of them where they have been hiding in the middle of the path. Another scene plays in some sort of cave with fog on the ground.

I remember seeing a movie when I was younger, but can't find it online because I can't remember a whole lot about the story.  What I do remember is there was a group of soldiers trying to catch this castle that appeared only during the day and at the start of each new day it would teleport to a new random location.  I also remember the main character having this neat little flying blade disk that reminds me of something from the Predator movies that he could control with his mind.  Again I can't recall a lot about the movie, but if it sounds familiar I would be grateful.  Also it seems like at one point there were horses that ran so fast they caught fire!


I can hold my finger on Pokeball and I can spin it before throwing it. Making this with a high speed makes the ball to sparkle. Does this throwing style increase the chance of catching any Pokemon?  P.S. I know the bonuses and I know how to throw a curve ball. You can get all types of bonuses without making it spin or spark. I just want to know if spinning or sparkling increases the chance of catching or not.

I found , earlier, and found out that I can throw a curveball at pokémon to earn an increased experience bonus.  I have since noticed two more bonuses: "Great" and "Nice". I had assumed the bonuses were for throwing a pokéball with the 'catch circle' closer to the center, which according to the FAQ, increases the chances of actually catching the pokémon.  However, I have since noticed that the 'catch circle' is actually bigger in cases where I have earned a "Great" bonus. Despite appearing to be a less powerful throw, I earn more experience than when I earn a "Nice" bonus. "Great" nets me 50 experience, while "Nice" only nets 10 experience.  What are the possible catch bonuses, and how much experience do they reward?  For bonus points, every so often I am awarded an additional 10 experience points that are not accounted for on the experience screen. The screen lists my bonuses, and tells me how much experience I have earned, but I am clearly rewarded additional experience when it is added to my player. Assuming this is another catch bonus, what could this be?


In Minecraft 1.12.2, is there a way to remove a series of stone and change it with air without breaking or changing other blocks?

I'd like to be able to select a region (either with a graphical utility or command line) and be able to switch one block type with another, e.g. change all cobblestone in the region to stone. Does a program/mod exist that can do this?


I am trying to create a macro which gets 3 nodes as input and then draws some kind of ellipse (a hyperedge) around these 3 nodes. This is how I currently draw the edges, but I would like to automate the process.  \documentclass[tikz]{standalone} \usetikzlibrary{topaths,calc,patterns}  \begin{document} \begin{tikzpicture} \def \r {1.2cm} \def \n {8} \def \vxsize {0.2cm}   \pgfdeclarelayer{bg}    % declare background layer \pgfsetlayers{bg,main}  % set the order of the layers (main is the standard layer)  \foreach \i in {1,...,\n} {     \pgfmathsetmacro\angle{(\i -1)*360/\n}     \node[draw=black,fill=black!50, circle, minimum width = \vxsize, inner sep=0cm] (u\i) at (\angle:\r) {}; }  \node (v) at (270:\r+0.5cm) {loose cycle};  \begin{pgfonlayer}{bg} \begin{scope}[fill opacity=0.5] \foreach \i in {2,4,...,\n} {     \pgfmathsetmacro\anglea{(\i -1)*360/\n - 8}     \pgfmathsetmacro\angleb{(\i)*360/\n}     \pgfmathsetmacro\anglec{(\i +1)*360/\n + 8}     \filldraw[fill=red, draw=black, thick] (\anglea:\r)      to[out = \anglea, in = \angleb + 270] (\angleb:1.27*\r)      to[out = 90 + \angleb, in = \anglec] (\anglec:\r)     to[out = 180 + \anglec, in =90+ \angleb] (\angleb:0.73*\r)     to[out = 270 + \angleb, in = 180+\anglea] (\anglea:\r); } \end{scope} \end{pgfonlayer} \end{tikzpicture} \end{document}     My basic approach is as follows:  \newcommonad{\hyperedge}[3]{% \coordinate (P1) at (#1); \coordinate (P2) at (#2); \coordinate (P3) at (#3); \begin{scope}[shift = (P2)] **Get x and y coordinates of (P1)-(P2) and (P3)-(P2)** [draw the edge] \end{scope}  }  \node (v1) at (0,3); \node (v2) at (1,2); \node (v3) at (3,2); \hyperedge{v1}{v2}{v3}   Is there a simple way to get the x and y coordinates in line 6 so that they are stored in variables x_1, y_1, x_3, y_3? Once I have this, I should be able to draw the shape (I hope).  Many thanks!

I'm trying to draw a boundary around a convex set of circular nodes in TikZ. The aim is to have it padded by 1cm, with an arc at the corners between segments, like this:    I currently have the following code:  \documentclass{article} \usepackage{tikz} \usetikzlibrary{calc}  \begin{document} \begin{tikzpicture}[every node/.style={circle,draw=blue}]    \node at (0,0) (a) {};   \node at (1,3) (b) {};   \node at (2,2) (c) {};    \draw[red]   ($(a)!1cm!-90:(c)$)   let \p1 = ($(a)!1cm!-90:(c) - (a)$),     \n1 = {atan2(\x1,\y1)},     \p2 = ($(a)!1cm!90:(b) - (a)$),     \n2 = {atan2(\x2,\y2)},     \n{delta} = {-Mod(\n1-\n2,360)}   in      arc [start angle=\n1, delta angle=\n{delta}, radius=1cm]   --   ($(b)!1cm!-90:(a)$)   let \p1 = ($(b)!1cm!-90:(a) - (b)$),     \n1 = {atan2(\x1,\y1)},     \p2 = ($(b)!1cm!90:(c) - (b)$),     \n2 = {atan2(\x2,\y2)},     \n{delta} = {-Mod(\n1-\n2,360)}   in      arc [start angle=\n1, delta angle=\n{delta}, radius=1cm]   --   ($(c)!1cm!-90:(b)$)   let \p1 = ($(c)!1cm!-90:(b) - (c)$),     \n1 = {atan2(\x1,\y1)},     \p2 = ($(c)!1cm!90:(a) - (c)$),     \n2 = {atan2(\x2,\y2)},     \n{delta} = {-Mod(\n1-\n2,360)}   in      arc [start angle=\n1, delta angle=\n{delta}, radius=1cm]   -- cycle;  \end{tikzpicture} \end{document}   I'm going to have to draw a lot of these, so it would useful if I could replace the \draw statement by something like:  \draw[red] \convexpath{(a) (b) (c)}{1cm};   where (a) (b) (c) are the nodes in the corners of the convex set in a clockwise direction. In the case of one node I would like it to draw a circle of the specified radius around the node in question.  Does anyone have any suggestions for how to go about writing such a macro?


I'm running Ubuntu 14.04.4 LTS, and I'm trying to install a new package using apt-get. Unfortunately, whenever I try I get messages like:  The following packages have unmet dependencies:  linux-image-extra-3.16.0-70-generic : Depends: linux-image-3.16.0-70-generic but it is not going to be installed  linux-image-generic-lts-utopic : Depends: linux-image-3.16.0-70-generic but it is not going to be installed  linux-signed-image-3.16.0-70-generic : Depends: linux-image-3.16.0-70-generic (= 3.16.0-70.90~14.04.1) but it is not going to be installed   Doing some googling, I found that  (and sure enough, df shows /boot at 100%). However, any time I try running the apt-get commands in the accepted answer there, I get the same errors as above.  Looking for another solution that didn't use apt-get, I came across , which recommends using things like sudo dpkg --purge linux-image-4.2.0-15-generic on old, unused kernels.  dpkg -l | tail -n +6 | grep -E 'linux-image-[0-9]+' | grep -Fv $(uname -r) (from the afore-mentioned post) shows that I have several old kernels in the pi state (desired purged, state is installed according to )  uname -r tells me the kernel I'm running is 3.16.0-62-generic, so I thought I should be safe to remove these old kernels. However, trying to do so with things like sudo dpkg --purge linux-image-3.16.0-49-generic results in:  dpkg: error processing package linux-image-3.16.0-49-generic (--purge):  dependency problems - not removing Errors were encountered while processing:  linux-image-3.16.0-49-generic   Garrg! I'm at my wit's end, and out of my depth (don't really know much about dpkg or apt-get), so I need some help.   Questions:    Why can't I uninstall the old kernels with dpkg? If that question can't be directly solved, I guess ultimately I want to know: What do I need to do to get into a state where I can install new packages again?     Other things I have tried:   sudo apt-get autoremove : results in the original error about unmet dependencies sudo apt-get -f autoremove : results in:    Unpacking linux-image-3.16.0-70-generic (3.16.0-70.90~14.04.1) ... dpkg: error processing archive /var/cache/apt/archives/linux-image-3.16.0-70-generic_3.16.0-70.90~14.04.1_amd64.deb (--unpack):  cannot copy extracted data for './boot/vmlinuz-3.16.0-70-generic' to '/boot/vmlinuz-3.16.0-70-generic.dpkg-new': failed to write (No space left on device) No apport report written because the error message indicates a disk full error                                                                               dpkg-deb: error: subprocess paste was killed by signal (Broken pipe) Examining /etc/kernel/postrm.d . run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.16.0-70-generic /boot/vmlinuz-3.16.0-70-generic run-parts: executing /etc/kernel/postrm.d/zz-update-grub 3.16.0-70-generic /boot/vmlinuz-3.16.0-70-generic Errors were encountered while processing:  /var/cache/apt/archives/linux-image-3.16.0-70-generic_3.16.0-70.90~14.04.1_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1)     Note: I've migrated this question from

Sorry for asking about what is probably really simple, but I've been Googling about for a week now and I've tried a lot of stuff without success.  To start off, I get a pop-up every time I boot saying my /boot partition is full, and the Synaptic Manager says linux-image-generic is broken, but it fails to reinstall either of them (linux-image-extra-3.13.0-54-generic and linux-image-generic).  My terminal tells me to try using install -f to fix things so I've tried that, and this is what it returned. Sadly, I'm still learning and I haven't been able to crack the code, I would like some help  aksel@aksels-PC:~$ sudo apt-get install -f Reading package lists... Done Building dependency tree        Reading state information... Done Correcting dependencies... Done The following extra packages will be installed:  linux-image-3.13.0-54-generic Suggested packages:  fdutils linux-doc-3.13.0 linux-source-3.13.0 linux-tools The following NEW packages will be installed:  linux-image-3.13.0-54-generic 0 upgraded, 1 newly installed, 0 to remove and 344 not upgraded. 5 not fully installed or removed. Need to get 0 B/14,7 MB of archives. After this operation, 32,8 MB of additional disk space will be used. Do you want to continue? [Y/n] y (Reading database ... 431129 files and directories currently installed.) Preparing to unpack .../linux-image-3.13.0-54-generic_3.13.0-54.91_i386.deb ... Done. Unpacking linux-image-3.13.0-54-generic (3.13.0-54.91) ... dpkg: error processing archive /var/cache/apt/archives/linux-image-3.13.0-54-generic_3.13.0-54.91_i386.deb (--unpack):  cannot copy extracted data for './boot/vmlinuz-3.13.0-54-generic' to '/boot/vmlinuz-3.13.0-54-generic.dpkg-new': failed to write (No space left on device) No apport report written because the error message indicates a disk full error  dpkg-deb: error: subprocess paste was killed by signal (Broken pipe) Examining /etc/kernel/postrm.d . run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.13.0-54-generic /boot/vmlinuz-3.13.0-54-generic run-parts: executing /etc/kernel/postrm.d/zz-update-grub 3.13.0-54-generic /boot/vmlinuz-3.13.0-54-generic Errors were encountered while processing:  /var/cache/apt/archives/linux-image-3.13.0-54-generic_3.13.0-54.91_i386.deb E: Sub-process /usr/bin/dpkg returned an error code (1)


What would be nice references to learn about homological algebra in the context of abelian categories?  I have already some background in category theory however that would be my first contact with abstract homological algebra (although I have already studied some of it in particular categories).  Thanks.

Which books would you recommend, for self-studying homological algebra, to a beginning graduate (or advanced undergraduate) student who has background in ring theory, modules, basic commutative algebra (some of Atiyah & Macdonald's book) and some (basic) field theory?  I would especially like to hear your opinions on the following books:  A Course On Homological Algebra / P. J Hilton and U. Stambach  Introduction to Homological Algebra / Szen-Tsen Hu  Notes on Homological Algebra / Rotman  But other recommendations will also be appreciated.


Consider the following reproducible example: library(dplyr) library(psych)  set.seed(42) n <- 500  df <- data.frame(   loneliness = round(runif(n, 0, 1)),   pet = factor(round(runif(n, 0, 1))),   addiction = factor(round(runif(n, 0, 2))),   sex = factor(round(runif(n, 0, 1))) )  levels(df$pet) <- c('dog', 'cat') levels(df$addiction) <- c('none', 'low', 'high') levels(df$sex) <- c('male', 'female')  df_coded <- data.frame(   loneliness = df$loneliness,   psych::dummy.code(df$pet) %>% as_tibble() %>%  setNames(paste0('pet_', names(.))),   psych::dummy.code(df$addiction) %>% as_tibble() %>%  setNames(paste0('addiction_', names(.))),   psych::dummy.code(df$sex) %>% as_tibble() %>%  setNames(paste0('sex_', names(.))) )  model_formula <- as.formula(   paste0(     'loneliness ~ 0 +',       paste0(colnames(df_coded)[-1], collapse = ' + ')   ) )  print(glm(formula = model_formula, data = df_coded, family = binomial))  I want to  my variables since I am not interested in an intercept and don't want it to results in the intersections between the first levels of pet, addiction and sex. Hence, I want to evaluate each level of each of these three predictors separately. As you can see by my attempt above, fixing the intercept to 0 while keeping all predictors with each level in the model, works fine for the first variable (pet), but produces NA's for the last level of the subsequent variables (addiction and sex): > source('~/.active-rstudio-document')  Call:  glm(formula = model_formula, data = df_coded, family = binomial)  Coefficients:        pet_dog         pet_cat   addiction_low  addiction_none  addiction_high      sex_female        sex_male          0.49977         0.45998         0.02604        -0.02391              NA        -0.03488              NA   What is the reason behind this and how do I prevent it? Thanks

I am running a binomial logistic regression with a logit link function in R. My response is factorial [0/1] and I have two multilevel factorial predictors - let's call them $a$ and $b$ where $a$ has 4 factor levels  $(a_1,a_2,a_3,a_4)$ and $b$ has 9 factor levels $(b_1,b_2,\dotsc,b_9)$. Therefore:  mod <- glm(y ~ a + b, family = binomial(logit), data=pretend) summary(mod)   The model output would then show all the information about the model as well as the coefficients.  There is a factor level for both a and b missing (a1 and b1) from the summary output. I understand that it is constrained in the "intercept" of the model. I have read that if I want to remove the intercept term and see the estimates for those factor levels I can just add -1 to the model formula, i.e.:  mod2 <- glm(y ~ a + b - 1, family=binomial(logit), data=pretend) summary(mod2)   In the new model (mod2) the intercept term is then gone and variable a's factor-level a1 is given amongst the list of coefficients. But, variable b's factor-level b1 is still missing and given that there is no intercept term anymore, how can I interpret the odds-ratio for that factor level then?  Could someone please explain to me how to get the coefficient for b1 too and why this is happening?


I know that String is immutable and it's value can't be changed, but why does the value of the below StringBuffer doesn't change when sent like a method parameter. From my understanding it should have changed with the new value "bb". Thank you for your help.   class Ideone {      public static void main (String[] args) {          String s = "aa";         StringBuffer sb = new StringBuffer("aa");         modify(s, "bb");         modify2(sb, "bb");         System.out.println(s);         System.out.println(sb);     }      public static void modify(String s, String ss) {         s = ss;     }      public static void modify2(StringBuffer sb, String ss) {         sb = new StringBuffer(ss);     } }

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


For a 1 D random walk on $Z$ axis, starting at $z=0$, equal probability to go to right or left, what is the probability that during the first k steps the walker's position remains $z\leq m$?  This is also called the survival probability. I can write is as a sum of first passage time probabilities, but I am looking for a closed form.  Thanks,

Suppose ${X_t}$ is a random walk with mean zero. (either discrete or continuous time) Fix a time $T$.  What is: $P[X_t < 0 \text{ for all } t \leq T]$?  In words, what's the probability the random walk from $0$ to $T$ has never been above $0$? Thank you.


WARNING!!!: The question asks for temporarily breaking Ubuntu. There shall be no safe answers.  If you have important services running, important documents/files being edited, please note that you might not be able to recover/save your work. Please note that trying these answers is not recommended  unless you know what and why you're doing it, and it is not answerer's (or asker's, FWIW) fault if you break something.   I need a way to make my Ubuntu become unresponsive. No running shutdown scripts, no recovery from hanging state. Just a quick and dirty way for the system to go into derp mode. Recovery should be only via powering off and on again.  Assume three things:   I am root Non-bash solution ( so no fork bombs please, but command-line solution ok) filesystem must remain intact   To address :    derp mode basically means "computer runs, but that's it" "What you're actually trying to achieve". I think the title explains it pretty clearly. I want to make the OS unresponsive at will, where it won't be able to do anything. That's exactly what I'm trying to achieve. There's no debugging involved, there's no . I just need a way for system to lock up/crash/hang up where I can't do anything except hold the power down button.

What is the fastest and most efficient method to crash/break Ubuntu 14.10?


var a = ["1", "2"]; var b = ["a", "b"]; var c = [];   //Can someone suggest how do i push a and b into c such that c is a 2-dimensional array? (By using JavaScript)  //c should look like [["1","2"],["a","b"]]

How do I append an object (such as a string or number) to an array in JavaScript?


For example, fireball does 8d6 damage, and half as much on a successful dex save. Does half as much mean you take half as much as the total amount on the 8d6s, or do you only roll 4d6 instead? This is for DnD 5e.

I'm new to DnD, though not new to rpgs in general.  I'm a bit confused on the damage of spells. For example, the Fireball deals 8d6 fire damage on a failed saving throw, and half as much on a successfull one.  What exactly is "half as much" in this case?  Is it 4d6 (half the number of dice)? Do I throw 8d6, add them up and halve the sum? Or do I throw 8d3 (half each die)?


I read the answers on those questions ( && ), neither of them work for me!   % uname --operating-system --kernel-name --kernel-version --kernel-release  Linux 4.9.6-200.fc25.x86_64 #1 SMP Thu Jan 26 10:17:45 UTC 2017 GNU/Linux   I download/install st terminal (), and I would like to set it as my main terminal-emulator, but I did a huge mistake, which is running this command as root: % su -c 'chsh -s /usr/local/bin/st'.   Now, whenever I want to login/run a command as root, a message is printed: Can't open display. I tried the following commands (as shown below), but non of them work..  % env -i bash % su Password: Can't open display % su -c 'env -i bash' Password: Can't open display % su -c 'chsh -s /usr/bin/bash' Password: Can't open display % su -s bash Password:  su: using restricted shell /usr/local/bin/st Can't open display % su Password: Couldn't read from shell: Input/output error child finished with error '256' %    UPDATE: I tried to do as explained in the proposed answer   From the bootloader prompt, navigate to the regular entry you boot from. Instead of pressing Enter press e to first edit the kernel command line parameters In the editor that opens, use the arrow keys to find the line that starts with linux, go to its end and append init=/bin/sh to it. This will replace your init system temporarily by your system's shell and since init is started by root, this will be a root shell. Press CTRL+X to boot the modified entry run chsh again with the correct parameters   But when I did the step 4, I was faced with  screen!

Accidentally removed my gnome desktop and am stuck in tty1. Trying to reinstall the desktop and keep getting the error "user is not in the sudoers file". Having trouble adding my user, new to debian and am not sure how to correctly open/edit sudoers from tty1 (or really how to edit files from cmd line for that matter if someone could please lend some specifics)!


I'm trying to write a proof but I have been stuck for the past few hours trying to make progress. I have to prove that  For all integers $n$, $m$, and $p$, if $n| (72m–p)$ and $n| (8m)$, then $n|p$.  I tried substituting $72m-p$ for $x$, and $8m$ for $y$, but I'm not really sure where to go from there.

How would I formally prove that for the integers $a$, $b$, and $d$, if $d\mid da+b$, then $d\mid b$? Would a direct proof be the best option? If I do a direct proof I seem to get stuck pretty quickly... in fact I don't even know how to start...   Assume $d\mid da+b$ ... ?  This might look like a HW dump but I honestly just don't know how to continue...


Chirality, helicity as a projection of its spin vector .. that becomes a kind of 'virtual spin'?  I often confuse them: but the particles 'spin' on the right or left, or is the projection of .. what? Left or right is a simbolic term to describe a particle degrees of freedom?

Polarisation, spin, helicity, chirality and parity keep confusing me. They seem to be related, but exactly how they are related is unclear to me. Can someone maybe give a short overview about what these quantities mean and how they are related? What are the values for e.g. basic particles like electron or photon?


Replace will create new object and both side this new will be compared. then why it showing false.   When exactly created new string will be added in string pool?  if("String".replace("g", "G") == "String".replace("g", "G")) {     System.out.println("True");     } else {     System.out.println("False");  }

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 am running Ubuntu 18.04 and I cannot get my system to work with Nvidia drivers.  Every time I select any proprietary Nvidia driver (other than the Noveau driver), I get errors.  This is the error I usually get:  You might want to run 'apt --fix-broken install' to correct these. The following packages have unmet dependencies:  libnvidia-ifr1-390 : Depends: libnvidia-gl-390 but it is not installed  libnvidia-ifr1-390:i386 : Depends: libnvidia-gl-390:i386 but it is not installed  nvidia-driver-390 : Depends: libnvidia-gl-390 (= 390.48-0ubuntu3) but it is not installed                      Recommends: libnvidia-gl-390:i386 (= 390.48-0ubuntu3) E: Unmet dependencies. Try '' with no packages (or specify a solution).   So, I run sudo apt --fix-broken install as it prompts me, and then I get the following error:  dpkg-divert: error: mismatch on package   when removing 'diversion of /usr/lib/x86_64-linux-gnu/libGL.so.1 by libnvidia-gl-390'   found 'diversion of /usr/lib/x86_64-linux-gnu/libGL.so.1 to /usr/lib/x86_64-linux-gnu/libGL.so.1.distrib by nvidia-340' dpkg: error processing archive /var/cache/apt/archives/libnvidia-gl-390_390.48-0ubuntu3_amd64.deb (--unpack):  new libnvidia-gl-390:amd64 package pre-installation script subprocess returned error exit status 2 Errors were encountered while processing:  /var/cache/apt/archives/libnvidia-gl-390_390.48-0ubuntu3_i386.deb  /var/cache/apt/archives/libnvidia-gl-390_390.48-0ubuntu3_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1)   Can anyone help me fix this?  EDIT 1: I completely uninstalled ALL Nvidia drivers, and then just tried to install the 390 drivers. I got the following error message:  E: /tmp/apt-dpkg-install-nItDms/11-libnvidia-gl-390_390.48-0ubuntu3_amd64.deb: new libnvidia-gl-390:amd64 package pre-installation script subprocess returned error exit status 2 E: /tmp/apt-dpkg-install-nItDms/14-libnvidia-gl-390_390.48-0ubuntu3_i386.deb: new libnvidia-gl-390:i386 package pre-installation script subprocess returned error exit status 2

I've had Nvidia drivers work successfully before.  I switched to Nouveau for a little while since a game wasn't working properly, then switched back to Nvidia only to be notified of an error.  I have uninstalled and re-installed the Nvidia driver multiple times now but keep getting the same errors.  diversion of /usr/lib/x86_64-linux-gnu/libGL.so.1 to /usr/lib/x86_64-linux-gnu/libGL.so.1.distrib by nvidia-340 dpkg-divert: error: mismatch on package   when removing 'diversion of /usr/lib/x86_64-linux-gnu/libGL.so.1 by libnvidia-gl-390'   found 'diversion of /usr/lib/x86_64-linux-gnu/libGL.so.1 to /usr/lib/x86_64-linux-gnu/libGL.so.1.distrib by nvidia-340' dpkg: error processing archive /tmp/apt-dpkg-install-JJFsm3/13-libnvidia-gl-390_390.48-0ubuntu3_amd64.deb (--unpack): new libnvidia-gl-390:amd64 package pre-installation script subprocess returned error exit status 2  Errors were encountered while processing:  /tmp/apt-dpkg-install-JJFsm3/13-libnvidia-gl-390_390.48-0ubuntu3_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1)   Installation method is sudo ubuntu-drivers autoinstall


How much priority should be given to grammar, spelling and punctuation when editing a question? How relevant are those? Should questions and answers be edited because of the sole reason there are spelling/grammatical errors?

Question says it all:  Should users edit other users' posts to correct grammar and spelling problems?  I've seen arguments both ways, and lean toward yes...but...


How would one show that that $$f(x,y) = \frac{xy(x^2-y^2)}{x^2+y^2}$$ for $(x,y) \neq (0,0)$ and $f(x,y)=(0,0)$ if $(x,y)=(0,0)$ has second order partials but $f_{xy}(0,0) \neq f_{yx}(0,0)$.  I was thinking of just trying to directly compute or evaluate the difference quotients but this is really long and messy, is there a simpler way?

Consider the function $f(x,y)=\dfrac{xy(x^2-y^2)}{x^2+y^2}$ for $(x,y) \neq (0,0)$, $f=0$ otherwise.  I have to compute $\dfrac{d^2f}{dydx}(0,0)$.  I know that I have to calculate $\frac{df}{dx}$ first. But that is ,  $\frac{df}{dx} = \frac{\partial f}{\partial y}\frac{dy}{dx}+\frac{\partial f}{\partial x}$. When I put it in wolframalpha, it gives me this calculation, and also just $\frac{\partial f}{\partial x}$ as an alternative form.   Why do I just ignore the y'? I don't know what y(x) is, as a function of x.  y and x are independent functions, no?


I just noticed that Ubuntu 15.04 is using bsd version of column command and its very old i.e. its from 2004. But on arch linux the column command is of util-linux is updated on 2014. So I have two questions: why Ubuntu 15.04 (debian jessie, both being latest release) is giving the old version binaries?  Is there any way to update these kind of core utils?

Why are packages in the official Ubuntu repositories older than the latest (upstream) versions from Debian Sid, PPAs, the authors, etc.?


I have a python regex like this:  re.compile(r'(\[chartsjs\].*\[/chartsjs\])', re.DOTALL)   I am trying to do a re.findall on patterns like this:  [charts] name: mychart type: line labels: fish, cat, dog data: 4, 5, 6 data2:5, 7, 9 [/charts]  this is some text  [charts] name: second type: line labels: 100, 500, 1000 data: 50, 100, 10000 data2: 100, 100, 100 [/charts]   But it seems like it is matching the first [charts] to the very last [charts] and grabbing everything in the middle, because when I print it to the console I am seeing this:  [u'[chartsjs]\r\nname: mychart\r\ntype: line\r\nlabels: fish, cat, dog\r\ndata: 4, 5, 6\r\ndata2:5, 7, 9\r\n[/chartsjs]\r\n\r\nthis is some text now fool\r\n\r\n[chartsjs]\r\nname: second\r\ntype: line\r\nlabels: 100, 500, 1000\r\ndata: 50, 100, 10000\r\ndata2: 100, 100, 100\r\n[/chartsjs]']   I would like the regex to return the first match, eliminate the arbitrary test and then find another arbitrary number of matches. Is there a way to do this?

I have this gigantic ugly string: J0000000: Transaction A0001401 started on 8/22/2008 9:49:29 AM J0000010: Project name: E:\foo.pf J0000011: Job name: MBiek Direct Mail Test J0000020: Document 1 - Completed successfully  I'm trying to extract pieces from it using regex. In this case, I want to grab everything after Project Name up to the part where it says J0000011: (the 11 is going to be a different number every time). Here's the regex I've been playing with: Project name:\s+(.*)\s+J[0-9]{7}:  The problem is that it doesn't stop until it hits the J0000020: at the end. How do I make the regex stop at the first occurrence of J[0-9]{7}?


Question: $$\tan 9 - \tan 27 - \tan 63 + \tan 81$$  Answer I'm getting : 0  What I did: Well I clubbed together $\tan 9$ and $\tan 81$ and $\tan 27$ and $\tan 63$ (took out negative as common). Then using the identity for $\tan (A+B)$, I rearranged to formula to get what $\tan A + \tan B$ is. With that I'm getting zero multiplied by $\tan 90$. Since anything multiplied by zero, even infinity, is zero, I guess it should be zero.  I'm pretty sure my logic fails me somewhere, please tell me where (probably in the infinity and zero multiplication part)

Calculate $\tan9^{\circ}-\tan27^{\circ}-\tan63^{\circ}+\tan81^{\circ}$?  The correct answer should be 4.


After Tomcat installation, before I even changed the default Tomcat Manager password, the attacker used Tomcat Manager to deploy his own software. Probably some DDOS tools and a file manager.  I've already removed the suspected java software, changed all user passwords. Root login via ssh was not permitted.  How do I act now to ensure the server is secure? What do I need to check? How to trace any other suspected activity?

This is a  about Server Security - Responding to Breach Events (Hacking)   See Also:                  Canonical Version I suspect that one or more of my servers is compromised by a hacker, virus, or other mechanism:   What are my first steps? When I arrive on site should I disconnect the server, preserve "evidence", are there other initial considerations? How do I go about getting services back online? How do I prevent the same thing from happening immediately again? Are there best practices or methodologies for learning from this incident? If I wanted to put a Incident Response Plan together, where would I start? Should this be part of my Disaster Recovery or Business Continuity Planning?   Original Version       2011.01.02 - I'm on my way into work at 9.30 p.m. on a Sunday because our server has been compromised somehow and was resulting in a    attack on our provider. The servers access to the Internet   has been shut down which means over 5-600 of our clients sites are now   down. Now this could be an FTP hack, or some weakness in code   somewhere. I'm not sure till I get there.      How can I track this down quickly? We're in for a whole lot of   litigation if I don't get the server back up ASAP. Any help is   appreciated. We are running Open SUSE 11.0.            2011.01.03 - Thanks to everyone for your help. Luckily I WASN'T the only person responsible for this server, just the nearest. We managed   to resolve this problem, although it may not apply to many others in a   different situation. I'll detail what we did.      We unplugged the server from the net. It was performing (attempting to   perform) a Denial Of Service attack on another server in Indonesia,   and the guilty party was also based there.      We firstly tried to identify where on the server this was coming from,   considering we have over 500 sites on the server, we expected to be   moonlighting for some time. However, with SSH access still, we ran a   command to find all files edited or created in the time the attacks   started. Luckily, the offending file was created over the winter   holidays which meant that not many other files were created on the   server at that time.      We were then able to identify the offending file which was inside the   uploaded images folder within a  website.      After a short cigarette break we concluded that, due to the files   location, it must have been uploaded via a file upload facility that   was inadequetly secured. After some googling, we found that there was   a security vulnerability that allowed files to be uploaded, within the   ZenCart admin panel, for a picture for a record company. (The section   that it never really even used), posting this form just uploaded any   file, it did not check the extension of the file, and didn't even   check to see if the user was logged in.      This meant that any files could be uploaded, including a PHP file for   the attack. We secured the vulnerability with ZenCart on the infected   site, and removed the offending files.      The job was done, and I was home for 2 a.m.            The Moral   - Always apply security patches for ZenCart, or any other CMS system for that matter. As when security updates are released, the whole   world is made aware of the vulnerability.   - Always do backups, and backup your backups.   - Employ or arrange for someone that will be there in times like these. To prevent anyone from relying on a panicy post on Server   Fault.


I'm working on a pong game with Processing. The game works just fine with a single class, however, I have to add multiple classes. Every time I get a Null Pointer Exception. This is part of the main class which extends PApplet  PApplet app = new PApplet();      void MAINMENU() {      // Start the Menu Song     if (musicStartMenu) {         MENUsong.loop();         musicStartMenu = false;     }      // Stop the Level song if needed     if (!musicStart) {         BGsong.stop();         musicStart = true;     }      // Resetting player scores     ScoreP1 = ScoreP2 = 0;      // Creating the Background for this scene     image(menuBG, 0, 0);     textFont(SC);      // Setting the title     text("PONG", width / 2 - 100, 150);      // Creating the buttons for this scene    Button Play= new Button(width / 2 - 150, height / 2 - 70, 300, 100, "PLAY", width / 2 - 100, height / 2 + 10, 1, 1,MAIN,app);    Button Exit= new Button(width / 2 - 150, height / 2 + 70, 300, 100, "EXIT", width / 2 - 100, height / 2 + 150, 3, 2,MAIN,app);    Play.Create();    Exit.Create(); }   and this is the button class:  import processing.core.PApplet;   public class Button {  int Bx,By, width, height;  String label;  int labelW, labelH, action, style, MAIN; PApplet app;    public Button(int Bx, int By, int width, int height, String label, int labelW, int labelH, int action, int style, int MAIN, PApplet app) {      this.Bx = Bx;     this.By = By;     this.width = width;     this.height = height;     this.label = label;     this.labelW = labelW;     this.labelH = labelH;     this.action = action;     this.style = style;     this.MAIN = MAIN;     this.app = app; }  void Create(){     // Check if we hover the mouse over and select a style     if (ButtonBorder(Bx, By, height, width)) {          if (style == 1)             // light green             app.fill(100, 155, 100);         else if (style == 2)             // light red             app.fill(255, 100, 100);      } else app.fill(0, 50); // black transparent      // Nobody likes borders     app.stroke(0, 0);      // Create the button box     app.rect(Bx, By, width, height);      // CHeck if the mouse is pressed and is hovering above the button     if (app.mousePressed && ButtonBorder(Bx, By, height, width)) {          // Select scene on click         MAIN = action;     }        // SET the fill of the label and create the label     app.fill(255);     app.text(label, labelW, labelH); }   boolean ButtonBorder(int xB, int yB, int ButtonHeight, int ButtonWidth) {      // returns true if the mouse pointer is located inside the button      if (!(app.mouseX >= xB && app.mouseX <= xB + ButtonWidth))         return false;     if (!(app.mouseY >= yB && app.mouseY <= yB + ButtonHeight))         return false;      return true;  }   If anyone has any clue it would be of much help. I want to say that the code is working just fine in a method inside the main class but for some reason that I can't seem to find it doesn't work in another class.  Trace:       java.lang.NullPointerException at processing.core.PApplet.fill(PApplet.java:14521) at ButtonB.Create(ButtonB.java:41) at Pong.MAINMENU(Pong.java:205) at Pong.draw(Pong.java:161) at processing.core.PApplet.handleDraw(PApplet.java:2429) at processing.awt.PSurfaceAWT$12.callDraw(PSurfaceAWT.java:1557) at processing.core.PSurfaceNone$AnimationThread.run(PSurfaceNone.java:313)

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?


How can I upgrade to the latest Ubuntu version from the present version 11.10 on my DELL Inspiron N5050 laptop without data loss. Also inform how can download the latest version.

I am currently using Ubuntu 10.04. I know there is a 10.10 release, but can I upgrade directly to 11.04? Could you walk me through the steps please?


I'm trying to prove by MI. I have already distributed n+1, but now I'm stuck on how I can show 9 divides the RHS since $42n$ and $3n^3$ does not divide evenly.   $$(n+1)^3+(n+2)^3+(n+3)^3=3n^3+18n^2+42n+36$$

I'm trying to prove using induction that $9$ divides $n^3 + (n+1)^3 + (n+2)^3$ whenever $n$ is a non-negative integer. So far, I have:   Base case: $P(1) = (1) + (8) + (27) = 36, 36$ can be divided by $9$ so the base case is valid Inductive step: let $P(n)$ be the statement $9$ divides $n^3 + (n+1)^3 + (n+2)^3$. Assume $P(k)$ is true, so $9$ divides $k^3 + (k+1)^3 + (k+2)^3$.   And this is where I'm stuck. I'm not sure how to demonstrate that $9$ divides $P(n)$ when $n = k+1$. If someone could step me in the right direction that would be awesome. Thanks!


Questions which currently have bounties are visible on /questions?sort=featured, but  on the  to find questions which have previously been featured but are not featured anymore. There's : -- Answers awarded bounties  -- Shows answers that have been awarded bounties, most recent answers first.  SELECT post.Id AS [Post Link],         vote.BountyAmount AS Bounty,        post.CreationDate AS Date FROM Posts post      JOIN Votes vote ON vote.PostId = post.Id      JOIN Posts parent ON post.ParentId = parent.Id WHERE            vote.VoteTypeId = 9  AND       vote.BountyAmount <> 0              ORDER BY post.CreationDate DESC  which lists all the answers that have been awarded bounties, but that doesn't include questions that might be as old as 3 months, and doesn't give a good preview. Can the featured tab include history, or a hasbounty:1 search keyword be added?

I have a problem on SE in finding a question (and valuable answers) that has been listed on the "Featured" tab for some days. Now it's disappeared from this tab, presumably because bounty period is over, and I'm trying to find it by tag, but this gives too many irrelevant questions, so I gave up.  The question: is it possible to search (filter) questions that currently have, or ever have had a bounty?


I am a South African living in the Netherlands on a residence permit.  My husband is Dutch, and we are going on holiday to South Africa. I have a flight booked back from South Africa to Amsterdam, via Heathrow.  Do I need a transit visa for the UK? The  is not clear about how my Dutch residence permit would apply - and it's very expensive if I do need a visa!

Is there a website or some other way to find out if I need a transit visa for a short stop in the UK on my way somewhere else? Ideally this should give me the answer for all nationalities, and take into account any other visas I may have.