Makeup exams and posting solutions
Student missing exam for “medical reasons”
Manifold that is NOT smooth Could someone provide an example of a manifold that is not smooth? All manifolds that come to mind are smooth! By a manifold, I mean a hausdorff, second countable locally euclidean space. Papers published from an academic project (MSc or PhD) usually have two authors; the first author is the student who mainly conducted the research, and the second author is the professor who supervised the projects.  The corresponding author is the one who take the responsibility of a paper, and thus, some believe that students are not yet prepared to take this responsibility.  Ideally, who should be corresponding author for papers published by MSc or PhD projects?  I understand that it mainly depends on personal agreements and preferences, but I want to know which case is more reasonable from academic logic? How to get this only in small letters (lowercase)? I used the following code to give out the category name (without link) in a single post.  How would it be possible for the category name that is given out to only appears in small letters ?  I just think this has to be made with substring, but I dont get it :) Could somebody please help me :)  &lt;?php foreach((get_the_category()) as $category) { echo $category-&gt;cat_name . ' '; } ?&gt; I am a new user, who has just been told to run / execute a command. The answer has some text with a grey background like this text here or  sometimes this text here.   However, I don't know what "run" or "command" means in relation to Ubuntu.  How do I do this?    This is intended for use as a Q&amp;A you can link to when you tell someone to run a command. Weird syslog order Have you ever seen wrong order in /var/log/syslog ? I think that it causes only crontab.  Jun 28 22:20:01 alex CRON[2327]: (root) CMD (something &gt; /dev/null) Jun 28 22:21:01 alex CRON[2700]: (root) CMD (something &gt; /dev/null) Jun 21 03:49:01 alex CRON[2753]: (root) CMD (something &gt; /dev/null) Jun 28 22:23:01 alex CRON[2754]: (root) CMD (something &gt; /dev/null) Jun 27 05:08:01 alex CRON[2813]: (root) CMD (something &gt; /dev/null) Jun 26 00:19:01 alex CRON[2816]: (root) CMD (something &gt; /dev/null) Jun 28 22:25:01 alex CRON[2816]: (munin) CMD (if [ -x /usr/bin/munin-cron ]; then /usr/bin/munin-cron; fi) Jun 28 22:25:01 alex CRON[2821]: (root) CMD (something &gt; /dev/null) Jun 28 22:27:01 alex CRON[3225]: (root) CMD (something &gt; /dev/null) Jun 28 22:28:01 alex CRON[3240]: (root) CMD (something &gt; /dev/null) Jun 28 22:30:01 alex CRON[3290]: (root) CMD (something &gt; /dev/null) Jun 26 12:03:01 alex CRON[3291]: message repeated 2 times: [ (root) CMD (something &gt; /dev/null)] Jun 28 22:30:01 alex CRON[3291]: (munin) CMD (if [ -x /usr/bin/munin-cron ]; then /usr/bin/munin-cron; fi) Jun 28 22:31:01 alex CRON[3659]: (root) CMD (something &gt; /dev/null) Jun 28 22:32:01 alex CRON[3754]: (root) CMD (something &gt; /dev/null) Jun 16 06:41:01 alex CRON[3846]: (root) CMD (something &gt; /dev/null) Jun 28 22:35:58 alex cron[909]: (CRON) INFO (pidfile fd = 3) Jun 28 22:35:58 alex cron[944]: (CRON) STARTUP (fork ok) Jun 28 22:35:58 alex cron[944]: (CRON) INFO (Running @reboot jobs) Jun 28 22:36:01 alex CRON[1428]: (root) CMD (something &gt; /dev/null) Jun 28 22:37:01 alex CRON[3050]: (root) CMD (something &gt; /dev/null) Jun 28 22:38:01 alex CRON[3082]: (root) CMD (something &gt; /dev/null) Jun 28 22:39:01 alex CRON[3114]: (root) CMD (something &gt; /dev/null)   As you can see, there is bad time order between lines. It is just crontab error, or there is some problem with system clock, or something?  I am running the latest Ubuntu 14.04 kernel:  Linux alex 3.13.0-30-generic #54-Ubuntu SMP Mon Jun 9 22:45:01 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux Vote for Tag Synonyms Directly on the Page Before:  After:   The pros:  Speeds up the tag synonym voting process. Easier to locate (as opposed to navigating to each individual tag wiki page). Encourages users to vote on more than one at a time.  The cons:  Serial up/downvoting. But this really isn't even an issue because, (1) only experienced users can vote on tag synonyms, and (2) more than one vote is required to approve a tag synonym, so the occasional serial up/downvoter won't significantly impact the overall process. Let $Z_n$ be the set of all $n \times n$ matrices that commute with all $n \times n $ matrices. Show that $$Z_n = \{\lambda I_n \ | \  \lambda \in \mathbb R\}$$  ($I_n$ is the $n \times n$ identity matrix)  I don't know how to use $E_{ij}$ (matrix with $1$ in $(i,j)$ and $0$ elsewhere) and the elementary matrix $P_{ij}$ to prove this question. Can anyone explain it please? How to prevent negative comments/downvoted being deleted by re-posting answers Motivation behind standard deviation? Prove or the disprove the existence of a limit of integrals Let $A \subset \mathbb{R}^2$ be the annulus defined, in polar coordinates, as  $$ A = \{ (r, \theta) \in [0, \infty) \times [0, 2\pi) : 2 \leq r \leq 3 \} \, .$$ Let $F: A \to A$, $F:(r, \theta) \mapsto (r, r \theta \text{ (mod } 2\pi))$. Let $g : A \to \mathbb{R}$ be a continuous function. Discuss the existence of the limit $$ \lim_{n \to \infty} \int_A g \circ F^{(n)}(x) \, \text{d}x \, ,$$ where $F^{(n)} = F \circ F \circ \dots \circ F$ denotes the composition of $F$ with itself $n$ times.  I cannot find a way to attack this problem. Here's what I tried: if $g \circ F^{(n)}$ converged, I think we could take the limit under the integral sign. So I tried to show the convergence of $F^{(n)}$. If it converged, then the limit function must send every point to a fixed point of $F$. So I determined the fixed points of $F$. But I don't think $F^{(n)}$ converges. I'm writing a custom module for Drupal 8. It defines a field storage configuration object, in a file called modules/mymod/config/install/field.storage.bloom_stem.bs_twitter_ac.yml.  The problem is that this is not removed when I uninstall the module; it is apparently left behind because, when I re-install the module, I get a crash.   drush -y pm-uninstall mymod drush cr drush -y en mymod      exception 'Drupal\Core\Config\PreExistingConfigException' with message 'Configuration objects (field.storage.bloom_stem.bs_twitter_ac) provided by mymod already exist in active configuration'   So it seems I need to some how manually remove this configuration object. Do I need to provide some more code that deletes it when the module is uninstalled? PATH variable resets with reboot Just as the title indicates my PATH variable resets after every reboot. I read that I have to edit my bashrc file's PATH variable, but I don't have anything there that suggests anything related to the PATH variable. How can I make an application automatically start when I have logged in? Inverse of a diagonal matrix plus a constant I am looking for an efficient solution for inverting a matrix of the following form:  $$D+aP$$   where $D$ is a (full-rank) diagonal matrix, $a$ is a constant, and $P$ is an all-ones matrix.   gives a solution to the special case where all diagonal entries of $D$ are the same.  The  formula is also capable of providing a solution to this problem by setting appropriate $u$ and $v$, but it loses efficiency ($O(n^3)$ time complexity to compute) at high dimension. I am hoping to get a result in the same form so the space and time complexity are both $O(n)$. Was just wondering if there is any solid data available as to how many people are using ubuntu. I was also interested in the attrition rate with ubuntu users, etc. How to implement custom icons for my script/addon? Is it possible to use different icons other than the default set and how? How do you remove Nvidia's proprietary drivers? I always seem to have grief with Nvidia drivers and have often had to re-install Ubuntu: is there a better way to remove them? When I first installed the drivers, the display came up on 640 by 480.  I managed to set 2 screens to 1024 by 780 which was usable, but then Ubuntu recommended installing proprietary drivers (nvidia-current-updates 295.40-ubuntu1). After doing this and re-booting it shows LAPTOP and offers only 640 by 480 on a single screen.   Is there any way to revert to the original driver? Is there any way to find out if the new drivers work before installing them? - For years I have been hoping that it would be all fixed in the latest release… I always seem to fall for this! Divisibility by 7 What is the fastest known way for testing divisibility by 7? Of course I can write the decimal expansion of a number and calculate it modulo 7, but that doesn't give a nice pattern to memorize because 3 is a primitive root. I'm looking for alternative ways that can help you decide when a number is divisible by 7 by hand.  I'm sorry if this is a duplicate question, but I didn't find anything similar on the site. The moderator agreement is visible at the following URL:       I acknowledge and agree that as a moderator for Stack Exchange Inc.      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Stack Exchange Inc. reserves the   right to terminate my privileges as a moderator at any time without   warning.   It hasn't been updated with the new company name and still refers to Stack Exchange Inc. instead of Stack Overflow (Inc.?). Prove that for any finite sequence of decimal digits, there exists an $n$ such that the decimal expansion of $2^n$ begins with these digits.