The indefinite article "an" is used when the following word starts with a vowel sound. For example one write "an adjective" but "a noun".   However, when an abbreviation is used, should this be based on the expanded meaning, or on the letters of the abbreviation.  Specifically, one writes "a noun phrase". However, here on ell.se, the abbreviation "NP" for 'noun phrase" is commonly used. If this were pronounced by sounding out its letters, as "En-Pee" it would call for "an". If it were read as "noun phrase"  it would call for "a". Should one write "a NP" or "an NP" here on ELL?  I incline to "a NP" and i used that in  just a few minutes ago, but I am not at all sure.
Taking notes, I was going to write this:     therefore p′ is a shortest path.   But the topic is APSP which stands for "all pairs shortest paths" so I decided to just write SP instead and...  Is it written with a like this     therefore p′ is a SP   or with an like this (because in my head I would "read" the S)     therefore p′ is an SP
Regular (non-moderator) users should be able to override deletions by Community user There is a question on  that got deleted by the Community user. This question isn't terrible (we have worse one's there), and I'm not complaining about this question in particular.  I wanted to vote to undelete it. However, it says "A moderator has deleted this post and it cannot be undeleted". This "moderator" is Community!  I understand if a "real" live human moderator (no offense to all non-humans out here) deleted this question that we can't override it. But this is a Robot! It sees that it got a downvote, no answer and little activity for a while and just deletes it.  Can we have "Community user" have rights to delete, but have those "deletions" subject to normal-person override? Chrome: Site has updated in the background I keep getting these notifications despite not having an RT tab open. What gives? Does Earth's Rotation Affect Its Shape? How do I instantiate a string array object into a Spring.Net container? Are there network-wide reputation leagues? I would love to see which people have the most network-wide reputation, how can I see that? How do I attach events to dynamic HTML elements with jQuery? How do I blend multiple photos to remove random people from the background? I'm very excited about the new  for Android/iPhone. Let's say you're taking a picture of your friend in front of a landmark with several people walking by. The app allows you to remove the people from the photo, leaving only the background and your friend. The app isn't just doing a clone of the surrounding image to paint over unwanted subjects. It's actually taking multiple images, detecting which objects are moving, and letting you select them for removal. This sounds awesome! But I don't want to be limited to taking pictures with a smart phone.  I would like to take multiple photos of the same scene. (Maybe with a tripod, but it would be better if I didn't have to use a tripod.) Then I would somehow blend them together to remove unwanted elements. How do I do that? I know there are tons of photoshop tutorials out there, but all the ones I find just tell you how to use the clone tool. The sign in the formula for the voltage across the inductor This question is about voltage induced in a inductance.  I know the rate of change of current induces EMF in the inductor. The direction of the induced EMF will be opposite to the change that is causing it. The EMF induced is given by the following formula.  $$V_l = -L \frac{dI}{dt}$$  The negative sign indicates direction of induced emf across the coil is opposite the current change.     In the picture I have drawn current direction and \$V_l\$ direction.  If \$\dfrac{dI}{dt}\$ is postive, \$V_l\$ will be negative according to formula right? Or does the direction of \$V_l\$ has to be reversed?  In many Internet references I found \$V_l = L \dfrac{dI}{dt}\$. Which one is correct?  I hope they reversed \$V_l\$ reference points and removed the negative sign in the formula. Please clarify. Inequality Proof in Real Numbers: If $p+q=1$ then $pq\le\frac14$ Let $p,q \in \mathbb R$, and $p+q=1$. Prove that $$pq \le \frac{1}{4}.$$   The first thing I did was define 3 possibilities that we can have from $p+q=1$:  1º  $p$ or $q$ is negative. Example:   $p=-10$, $q=11$   $-10+11=1$  $(-10)(11)=-110$  So if $p$ or $q$ are negative the inequality $pq$ $\le$ $\frac14$ holds.  2º $p$ or $q$ is $0$, that makes the inequality $pq$ $\le$ $\frac14$ be $0$ $\le$ $\frac14$, the inequality holds.  3º The final possibility I saw  was $0$ $\lt$ $p,q$ $\lt 1$, here i just see that the max value from $p,q$ can be $p,q = 1/2$ making $\frac12 + \frac12 = 1$ and $(\frac12) (\frac12) \le \frac14$, but i do not see the elegant way of proving that with other values the inequality holds.  I apologize in advance if I made any mistake or missed something. New tags page mangles tag wiki excerpts How can I scale all images in a folder to the same width? I want to scale all images in a given folder to the same width (but different appropriately scaled heights). How can I do this using  a GUI-based or command-line tool?  For bonus points, is it possible to restrict which images are scaled based on their initial width (that is, only scale images that have a width > x and/or a width &lt; y)? How does Hisoka see Gon exactly? As a rival or as a toy to entertain himself? Hisoka hinted that Gon is his treasure and also his prey, but it can't be both, right? Because in the end, he didn't want Gon to die no matter what.  So it's weird that he didn't want Gon to die but also made him his prey to fight till death. Is it sexual for Hisoka or what? I still remember the 'Schwing' thing. Make clear which profile data is visible to whom How typeset a numeric table from a CSV file I have a CSV file (db.txt)like this:  30.0,   0.0,    0.0 60.0,   1.9098, 5.8779 90.0,   6.9098, 9.5106 120.0,  13.09,  9.5106 150.0,  18.09,  5.8779 180.0,  20.0,   0.0   I need to typeset it. My problem is related with the wrong alignment of decimal point and the number of decimals (must be a constant for each column):  \renewcommand*{\dtlrealalign}{r}  \DTLloaddb[     noheader,     keys={x,y,theta},     headers={         \shortstack{$\boldsymbol{\theta_{2,i}}$},         \shortstack{X},         \shortstack{Y}              }   ]{db}{db.txt} \begin{table}[t]   \caption{Database file}   \centering   \DTLdisplaydb{db} \end{table}     Any advice, please? Consider this equation :   $$\sqrt{\left( \frac{dy\cdot u\,dt}{L}\right)^2+(dy)^2}=v\,dt,$$  where $t$ varies from $0$ to $T$ , and $y$ varies from $0$ to $L$.  Now how to proceed ?   This equation arises out of following problem :   A cat sitting in a field suddenly sees a standing dog. To save its life, the cat runs away in a straight line with speed $u$. Without any delay, the dog starts with running with constant speed $v&gt;u$ to catch the cat. Initially, $v$ is perpendicular to $u$ and $L$ is the initial separation between the two. If the dog always changes its direction so that it is always heading directly at the cat, find the time the dog takes to catch the cat in terms of $v, u$ and $L$.  See my solution below :   Let initially dog be at $D$ and cat at $C$ and after time $dt$ they are at $D'$ and $C'$ respectively. Dog velocity is always pointing towards cat.  Let $DA = dy, \;AD' = dx$  Let $CC'=udt,\;DD' = vdt$ as interval is very small so $DD'$ can be taken straight line.  Also we have $\frac{DA}{DC}= \frac{AD'}{ CC'}$ using triangle property.  $\frac{dy}{L}= \frac{dx}{udt}\\ dx = \frac{dy.udt}{L}$  $\sqrt{(dx)^2 + (dy)^2} = DD' = vdt \\ \sqrt{(\frac{dy.udt}{L})^2 + (dy)^2} = vdt $  Here $t$ varies from $0-T$, and $y$ varies from $0-L$. Now how to proceed? How to define binary operation on arbitrary set in order to create a group structure. How to setup Java-Home and Path in Ubuntu 12.04 Dual booting Windows and Ubuntu My laptop has 500gb hard disk in which for 250gb I installed Windows xp on C drive(primary partition). I want to install Ubuntu 12.04 in the remaing hard drive with dual boot option. When I am going to install Ubuntu it is showing something like  /boot /boot/   Can anybody help me in this regard that where and how to install Ubuntu? By default after a new user signs up, a redirect to the home page happens.  But in such case I want to redirect such user to another page like node/35.  In this node/35 I then want to display some content. How to add a user to sudoers file? I have an account named as Chankey (local user). I had to use some commands like viewing the shadow file etc. I tried it using sudo command     sudo vim /etc/shadow   It said:      Chankey is not in the sudoers file. This incident will be reported.   How can I add this user Chankey to the sudoers file?