How to install programs compressed on linux
How do I install a .tar.gz (or .tar.bz2) file?
Consider the blow-up of the plane in one point. Let $E$ the exceptional divisor. We know that $(E,E)=-1$. What is the geometrical reason for which the auto-intersection of $E$ is $-1$? In general, what does it mean, geometrically, that a divisor has a negative self-intersection or that the "right" number of divisors gives rise to a negative intersection?  Thanks. We know that you can't transfigure food, so you have to grow it or buy it. Ditto money.  I'm sure that aside from some medicinal plants Herbology Professor had there were no farmlands at Hogwarts. So they must have bought food (as well as potions ingredients for Snape etc...). And they needed to pay the teacher salaries.  Where did all that money come from according to canon?  Ministry funding?  Tuition?  Patent money on Dumbledore's inventions?  Philanthropic donations by Malfoys and co?  Other? Heres a picture. im making a body, and it seems to have flash in the middle. I just moved to a new computer: Windows 10 with XAMPP. As far as I know I set everything up the same as it was on my old Windows 7 computer. But now, for some reason, much of the time when I run drush cc all or run update.php, the database gets corrupted. Most frequently, some cache tables' *.idb files (tablespaces) are deleted from my mysql directory, which makes those tables appear as "in use" in phpMyAdmin and prevents them from being edited or emptied. They are always cache tables and never tables that actually get modified by my update hooks. Restoring the database is the only way to fix it then. This is a mature site that I've been working on for a long time, and have never seen this until the new computer. What's happening here?  A sample error message when using update.php, caused by a missing *.idb file:  PDOException: SQLSTATE[HY000]: General error: 1812 Tablespace is missing for table '(null)': DELETE FROM {cache_field} WHERE (cid = :db_condition_placeholder_0) ; Array ( [:db_condition_placeholder_0] =&gt; field:message_type:6 ) in cache_clear_all() (line 168 of C:\&lt;path&gt;\includes\cache.inc).   My most recent drush cc all error message, which Google has never even heard of, was:  exception 'PDOException' with message 'SQLSTATE[HY000]: General      [error] error: 1030 Got error -1 "Internal error &lt; 0 (Not system error)" from storage engine InnoDB' Find an example where Markov's inequality is tight in the following sense: For each positive integer $a$, find a non-negative random variable $X$ such that $P(X\ge a)=E(X)/a$.   How to do this problem, I am really confused. Also, what is the definition of Markov's inequality? String Comparison in Java I used this isomorphism today but now I'm having trouble justifying it. The norm function isn't additive so I can't come up with a ring isomorphism to prove the following:     For any $\,a+bi\in\Bbb Z[i],\,\gcd(a,b)=1$, we have a ring isomorphism   $$\Bbb Z[i]/\langle a+bi\rangle\,\cong\Bbb Z/(a^2+b^2)\Bbb Z=:\Bbb Z_{a^2+b^2}.$$   Could someone show me an isomorphism between these rings to prove this? How can I manage computers using my Firefox Sync account? I`m using Firefox Sync on a bunch of computers.   I would like to manage my account, by removing some computers. I can't find the place to do this, it should be on the Firefox Sync page, but the official page only has the privacy and download information. How would you categorize email subjects to find similar emails? I have a list of email subjects like:  &lt;XYZ&gt; commented on &lt;ABC&gt; Weekly review for &lt;Company&gt; Your account is ready    And I want to find patterns in them so I can group them.  Is there a well known algorithm I can use?    Preferably with wide language implementations or easy re-implementation. The algorithm should be unsupervised. The number of different emails is not known.   Update:  I think I can break this down into two problems:   Group subjects by the similar words they use, resulting in the following. Each group should be very distinct from the rest (they should be almost perfectly exclusive) and the algorithm should give relatively small number of groups with good length of the common words.  [commented, on] [weekly, review] [your, account, is, ready]  Once grouped, it should be easy to find a state automaton that accepts only the group's subject and thus eliminates variable Then I can go back and check if there are any intersections and tweak the variables.   Having said that, is it better to use a completley different approach like neural nets maybe? I have zero experience with those, but if it makes more sense, I am open to learning. Difference between sentences using 'was' and 'being'? What is the meaning of below sentences using was and being?     He committed suicide after he was severely beaten up by four teachers. He committed suicide after being severely beaten up by four teachers. I am married to a UK citizen. What type of visa do I need to travel to the UK for tourism? I am a Bangladeshi citizen married with my husband who is a British citizen by birth. Currently, we both live in Bangladesh and my husband works at a university. We, are planning to visit UK for about 3 weeks. Just to be clear, we have no intention to settle down in the UK.  Do I need to apply for a visa? If so, then what type of visa should I apply for?  N.B. I've been searching on the internet (including the UK border agency website) for hours now but couldn't get a definite answer. Suppose we have an object in space. say gravity is negligible, and the thing has a rocket on both sides. the thing fires one rocket for, say, 5 seconds. now it's moving. The object has kinetic energy. Now the other rocket fires for 5 seconds. Then it's stationary. where does the energy go? I know that some of the energy from the rockets would just go into space as heat and kinetic energy of the hydrogen particles flying out, but how does there seem to be more energy in the situation if the first rocket just goes for 10 seconds than if one goes for 5 and the other goes for 5? How do I unlock all the other ships in the hangar? Repeating an equation including its content and number I would like to re-use equations with the same content and number. I know that the thmtools package has a restatable environment to do this for environments (like in ), but I would also like to do this with a single equation that is only part of some environment.  I had a look at the following questions which only aim at repeating the equation number but typing the whole equation twice (the first three) or repeat the content of the equation without a number (the last one):         Based on the answers provided there and on the  I tried to create a macro \restatableeq for restable equations like this:  \documentclass{article}  \usepackage{amsmath}  \newcommand{\restatableeq}[3]{\label{#3}#2\xdef#1{\unexpanded#2\unexpanded\tag{\unexpanded\ref{#3}}}}  \begin{document}  \begin{eqnarray} \restatableeq{\eqone}{This &amp; is &amp; eqation 1}{eq1}\\ Another &amp; simple &amp; equation \end{eqnarray}  \begin{eqnarray} One &amp; more &amp; equation\\ \restatableeq{\eqtwo}{This &amp; is &amp; eqation 2}{eq2} \end{eqnarray}  Here, we use (\ref{eq1}) and (\ref{eq2}) again: \begin{eqnarray*} \eqone\\ \eqtwo \end{eqnarray*}  \end{document}   Unfortunately, it does not work and yields:  ! Missing { inserted. &lt;to be read again&gt;                    T l.10 ...ableeq{\eqone}{This &amp; is &amp; eqation 1}{eq1}                                                   \\ ?   My guess is that the &amp; symbols are not treated as intended but I may well be wrong there.  How can I define a command like \restatableeq that allows me to re-use equations with the same content and number in a setting like in this example (and give it a label such that I can still use \ref as usual in addition to that)? How can I upgrade Mac OS without the administrator password? I recently received an old iMac secondhand.  I have no way to reach the original owner. I am trying to upgrade the OS software, but the prompts demand the administrator's name (which is auto-filled) and password (which I do not have).  I understand why these security features are in place, but is there any way in the world for me to access Admin. privileges without the password? how to prove $\forall p$ prime :   $\binom{2p}{p} \equiv 2 \pmod p$ we have:  $\binom{2p}{p} = \frac{2p (2p-1)(2p-3)...1}{p!p!}$ but how to continue? How To Group Records By Value In A Specific Field? I have a List of records of type abc__c. abc__c is a custom object. The record has a field called code__c. What I am trying to accompolish is to group the records in the list based on the code__c.  For example the list might have :  Code__c     abc__c record 30       (Record 1) 40       (Record 2) 40       (Record 3) 50       (Record 4) 30       (Record 5)   I want to group these records based on Code__c in a Map. There could be any number of code__c which is populated dynamically. It is not static. how can I loop through the list and store the records as a list for a particular code__c(Id) in Map? Is momentum conserved in this situation? Suppose we have object A , which has momentum mv. Then it elastically collides with a wall, so it's momentum now -mv, So how is momentum conserved here ? When using the Stack Exchange App for Android, I encountered a problem when uploading multiple images to the same post.  After uploading a single image, the image Markdown is inserted normally, e.g.:  ![enter image description here][1]     [1]: http://i.stack.imgur.com/Cbh1m.jpg   As I upload more images, the list of URLs at the bottom of the post should be appended to. After uploading the above in a new post, I tap to place the cursor at the end of the first line, enter a newline and the toolbar reappears. I then upload a second image with this result:  ![enter image description here][1] ![enter image description here][2]     [1]: http://i.stack.imgur.com/Cbh1m.jpg   [2]: http://i.stack.imgur.com/V5nXV.jpg   Now I edit the image descriptions, to make sure I can keep track of all my images, place the cursor at the end of the second line and enter a newline. The edit box contains:  ![a black circle of utter blackness][1] ![the best planet earth clip art ever][2]      [1]: http://i.stack.imgur.com/Cbh1m.jpg   [2]: http://i.stack.imgur.com/V5nXV.jpg   I then upload a third image. What's interesting is that as the screen reloads, for an instant I see the best planet earth clip art ever replaced by more image markup, so the second line is this:  ![![enter image description here][2]][2]   But only for a moment. Then the screen updates, and the edit window is left in this state:  ![the best planet earth clip art ever][2] ![the best planet earth clip art ever][2] ![enter image description here][3]     [1]: http://i.stack.imgur.com/Cbh1m.jpg   [2]: http://i.stack.imgur.com/V5nXV.jpg   [3]: http://i.stack.imgur.com/6Ra5w.jpg   I correct the first line and insert a line break after the third line in preparation to upload the first image again (I really love blackness). Before uploading, the edit window looks like this:  ![a black circle of utter blackness][1] ![the best planet earth clip art ever][2] ![a fast computer][3]      [1]: http://i.stack.imgur.com/Cbh1m.jpg   [2]: http://i.stack.imgur.com/V5nXV.jpg   [3]: http://i.stack.imgur.com/6Ra5w.jpg   After uploading:  ![a fast computer][3] ![the best planet earth clip art ever][2] ![a fast computer][3] ![enter image description here][4]      [1]: http://i.stack.imgur.com/Cbh1m.jpg   [2]: http://i.stack.imgur.com/V5nXV.jpg   [3]: http://i.stack.imgur.com/6Ra5w.jpg   [4]: http://i.stack.imgur.com/ILUCC.jpg   Now, instead of adding a newline, I position my cursor at the end of the third line. The toolbar isn't visible so I insert a space and then delete it. I upload another copy of the third image from this position adjacent to other image markdown, and now the result is:  ![a fast computer][3] ![the best planet earth clip art ever][2] ![a fast computer][3]![enter image description here][4] ![enter image description here][4]      [1]: http://i.stack.imgur.com/6Ra5w.jpg   [2]: http://i.stack.imgur.com/V5nXV.jpg   [3]: http://i.stack.imgur.com/6Ra5w.jpg   [4]: http://i.stack.imgur.com/jG0fk.jpg   [5]: http://i.stack.imgur.com/ILUCC.jpg   Notice:   The new image, the fifth I have uploaded, goes in as image [4]. Not a problem, so far, but: The previous image description is still linked to image [4], now a different URL; and The first URL in the list has been overwritten by the URL of the third image, which happens to be immediately adjacent on the line where I inserted the most recently-uploaded image.   Reproduced at the time of this question revision, with the following specs:   Device: Moto G 2013 OS version: 4.4.4 App version: 1.0.57 The  was deleted last night by the Community user.    Normally, I wouldn't see an issue with this, but for this particular deletion, I can see three issues:   We try not to delete good content There are multiple upvoted answers We often use previous answers on Meta (as well as badly asked questions) to form the precedent (and to use as duplicates) when users ask questions like this in the future   On a personal note, I find it easier to link to one of my previous answers whenever possible.  This seems like a bug with the deletion algorithm, , the deletion algorithm should never delete questions with upvoted answers.  I'm going to go ahead and undelete it, but I'm bringing this up in case there was either:    A policy change A bug   So is it either of the above or something else?