Best simple textbook on lattice theory
Introductory text for lattice theory
Limiting number of lines in textarea I'm looking for a javascript that can limit the number of lines (by line I mean some text ended by user pressing enter on the keyboard) the user is able to enter in textarea. I've found some solutions but they simply don't work or behave really weird. The best solution would be a jquery plugin that can do the work - something like , but it should be able to limit text line count not character count. I have to format my entire disk and reinstall Ubuntu.  I have installed a lot of software on my current system. And I will have to reinstall all those updates, drivers and applications too.  Is there any way I can make an .iso image of my installed Ubuntu along with all the software, preferences, drivers etc in it ?  Is there any way I can back up my whole OS along with all its software, drives, updates and all ? I am trying to understand how to see the total size of my hard drive &amp; how much is left. It was recommended on various searches to use the command below   df -h Filesystem      Size  Used Avail Use% Mounted on udev            7.8G     0  7.8G   0% /dev tmpfs           1.6G  9.6M  1.6G   1% /run /dev/sda1       219G   29G  180G  14% / tmpfs           7.8G   18M  7.8G   1% /dev/shm tmpfs           5.0M  4.0K  5.0M   1% /run/lock tmpfs           7.8G     0  7.8G   0% /sys/fs/cgroup cgmfs           100K     0  100K   0% /run/cgmanager/fs tmpfs           1.6G   64K  1.6G   1% /run/user/1000   However I don't understand any of these directories. I mean what are they, are these all directories or partitions or what? And why do they appear under "mounted on"? How does that bit work. I assume the /dev/sda1 is my solid state drive? So now if I install applications, which one of these directories does my software get installed  into? I assume it just gets installs in the / directory (I haven't even got a clue what the / directory is). Can someone explain what the other directories are and what they are used for? Lightning component calling wrong overloaded apex class method Ideal column width for paragraphs online There is nothing worse than coming across a website with paragraphs that span the width of your screen resolution. They are usually so hard to read, I don't even bother.  A lot of web designers use generic grid and column systems, but I don't feel these have been optimised for readability, they are more of design guide on general aesthetics.  I guess it comes down to words per line. Are the rules that apply to print media the same for screen media?  Are there any type of guidelines to help me size the width of paragraphs on the screen?  I want to take into consideration:   Major web font faces (i.e. Arial, Verdana, Georgia, Times) A range font sizes (i.e. 8px-24px) Space between columns automatically apply special formatting to selected words in text Apply a string replacement on the citation as returned by \cite I have biblatex with options  \usepackage[backend=bibtex, style=authoryear]{biblatex}   The citations made with \cite look like this: Smith, 2019 or Smith and Baker, 2019 and so on. I would like to define a command that automatically replaces the occurrence of my name with my initials. Namely I need  \cite{SmithsPaper}  % --&gt; Smith, 2019 \cite{MyPaper}      % --&gt; Manny, 2019 %%% \newcite{SmithsPaper}  % --&gt; Smith, 2019 \newcite{MyPaper}      % --&gt; MC, 2019   I have tried with the package xstring to do something like  \newcommand{\newcite}[1]{%   \begingroup   \edef\@temp{\cite{#1}}%   \StrSubstitute{\@temp}{Manny}{MC}   \endgroup }   The problem is that I can't figure out how to tell LaTeX to expand \cite{#1}. As a result the citation comes out without the replacement. If I change \cite{#1} by simply #1 and I call \newcite{bla Manny bla} it gives bla MC bla as expected.  It shouldn't be relevant but I'm using this within the beamer documentclass. Is ignoring emails acceptable in academia? As a grad student, I just find it tremendously frustrating when emails are ignored by faculty (both at my institution and at other places). Is this acceptable? I'd be content with a simple response with one line along the lines of "I have read this email and am busy right now, will respond in X days when I can write a more detailed email." I understand that, as a first year student in my field, I'm not really in a position to request anything of anyone, but it just seems like common decency.  Instead, I never hear back, as if my email has been jettisoned off into oblivion. var/cache/apt/archives occupying huge space I am in the process of cleaning up my system. And I see a lot of space occupied by this folder /var/cache/apt/archives (1.5GB). Is it absolutely necessary to keep all these archives? What is the meaning of speed of light $c$ in $E=mc^2$? is the famous mass-energy equation of Albert Einstein. I know that it tells that mass can be converted to energy and vice versa. I know that $E$ is energy, $m$ is mass of a matter and $c$ is speed of light in vacuum.   What I didn't understood is how we will introduce speed of light?  Atom bomb is made using this principle which converts mass into energy; in that the mass is provided by uranium but where did speed of light comes into play? How can speed of light can be introduced in atom bomb? Is anti-gravity (i.e. repulsive gravity) possible in theoretical physics? Is  (i.e. repulsive gravity) possible in string theory?  I have read some articles about scientists making assumptions about the existence of anti-gravity, but is it possible in string theory? Accessing private member variables from prototype-defined functions Is there any way to make “private” variables (those defined in the constructor), available to prototype-defined methods?  TestClass = function(){     var privateField = "hello";     this.nonProtoHello = function(){alert(privateField)}; }; TestClass.prototype.prototypeHello = function(){alert(privateField)};   This works:  t.nonProtoHello()   But this doesn’t:  t.prototypeHello()   I’m used to defining my methods inside the constructor, but am moving away from that for a couple reasons. SQL Server equivalent to Oracle's CREATE OR REPLACE VIEW Which Mac is suitable for Blender 2.8? I am considering purchasing a Mac for my godson who will be using it to run Blender 2.8.  I know very little about this program.  All I can find are requirements for a Mac that will run earlier versions of Blender.  Would someone please recommend a list of requirements for a Mac (or a link to a list of requirements) that I could use to find a model that can run 2.8?  Thank you in advance for all your help! Sincerely, M. Lap Rings' second isomorphism theorem I am thinking about the proof of the second isomorphism theorem, and something isn't very clear to me.   Let $R$ be a ring, $S\subset R$ a subring and $I\subset R$ an ideal. We have the natural homomorphism $f:R\rightarrow R/I$. The theorem states that $\mathrm{Im}(S)=(S+I)/I$. My question is why not simply $\mathrm{Im}(S)=S/I$?  I understand that it is not true (for starters, $S/I$ need not be a subring), but I cannot explain that to my self in a convincing way. How can I get multiple stacked plots (ybar stacked, stack plots=y) in one diagram, such that there are multiple stacked bars for the same x-coordinate, each slightly shifted? Is there a way to reset pgfplot's zero levels after an \addplot command, such that the next \addplot[xhshift=...] doesn't add something to the current stack, but rather starts a fresh stack?  FWIW, overlaying two plots with scale only axis won't help; I need this to work with groupplot Prove the set of all infinite binary sequences is uncountable by using Cantor's theorem. This is different then the other versions of the questions here. I'm not supposed to use the diagonal argument. I'm looking to write a proof based on Cantor's theorem, and power sets. I read this set of stories in the 80's.  What I recall is this:  A planet where the ruling caste was made up of humanoid women.  These women would, as almost pubescent girls, go out into the wilderness with only a spear and attempt to kill an animal in a life or death struggle.  When it happened, they would burst open a DNA packet in themselves that caused them to rapidly mature, their skin to become bronze colored, and give them some kinds of other "powers", I think over fire.  They were called "Bahronas", I think.  The population of this planet was primitive, but they were in contact with an advanced humanoid species, I think of actual homo-sapiens, who were there observing and advising them.  The advanced species wasn't allowed to intervene, just advise and watch.  The main character was a castaway boy, crash landed on their planet and stranded.  He became friendly with the ruling family of Bahronas and entered their confidence.  We find out through the course of the story that he's been genetically engineered and is not a normal boy.  At some point, the advanced species notices him and explains that he is a clone of a famous explorer and a spy, and they explain that they won't do anything in front of him.  The central part of the story is something of a blur, but, the final part of the story is told in a dramatically different style and shifts to a planet populated by catlike creatures who live in boughs of silk scarves, some of which sing.  THey are recording devices which play back the songs.  On this planet, there is another silk scarf, a white one, which doesn't play a song at all.  The cat creatures are greatly disturbed by it when they hear it's message, which they don't understand.  The narrator then goes on to say that it's a spoken word recording, made by the explorer which the boy was a clone of, explaining that he is captured and held hostage on the planet which makes the scarves, and forced to help make them (I think.) I have a question about making an ending symbol.  It is a LaTex-default that every proof environment has an ending symbol. I want to make every theorem-alike environment such as the example environment have also an ending symbol. But how to manually set this up? Specifically, I want to make all these environments ended by a square symbol.  \newtheorem{thm}{Theorem} \newtheorem{lem}[thm]{Lemma} \newtheorem{cor}[thm]{Corollary} \newtheorem{pro}[thm]{Proposition} \newtheorem{assump}{Assumption} \newtheorem{axiom}{Axiom} \newtheorem*{conj}{Conjecture} \theoremstyle{definition} \newtheorem{defi}[thm]{Definition} \newtheorem{exam}{Example} \newtheorem{exer}{Exercise} \newtheorem*{rem}{Remark} \newtheorem*{notation}{Notation} \newtheorem*{note}{Note}   I am looking for, with gratitude, a comprehensive setup. What is "offset null" in IC 741? What is Offset null in 1st and 5th pin in IC 741 (Op-Amp)? Why it is used, though it is not used in many circuits? Give me explanation regarding the offset null! Why offset voltage was formed in IC 741?