The history behind the broken epsilon
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Parental controls with different settings for different users Does anyone know of a good way to set up some sort of parental controls so that one user account is subject to them, but not another?  A couple of friends of mine use Ubuntu and have kids (7 to 10 years old) who use the family computer. They'd like to have some blocking of adult sites. They're not going to supervise all the time, which I know might be ideal, but there we go. And they're not particularly technical, so they don't want to have to run scripts to turn the parental controls on and off regularly, but they can cope with having different accounts for different people. I haven't found a great way of doing this. I am pretty technical, so I'm happy to spend some time at the command line to set it up, but then it needs to just work.  Please don't just link to DansGuardian. If your answer doesn't address the different user account aspect, I will vote it down. If you want to talk about general parental controls that apply to all users then please start a new question - I'm sure that plenty of people would be interested in it, and I'll link to it from this question. How to increase difficulty in Dungeon World I've been GMing for a couple of sessions now and I'm still struggling at making encounters or situations more difficult. I will describe dangerous situations and encounters in fiction but the mechanics make it too easy for my players to succeed.  For instance no matter how big I describe the Troll, if the fighter of the party charges him and swing his sword, roll+2 for Hack and slash, he'll easily hit the troll. Almost 40% chance to hit without consequences. Recursive matching with regular expressions in Javascript Suppose $ T \subset \mathbb{C} $. Show that the corresponding set $ S \subset \Sigma $ is  a. a circle if $ T $ is a circle. b. a circle minus (0, 0, 1) if $ T $ is a line.  Here we are defining $ \Sigma $ to be the Riemann sphere, given by the set: $$ \Sigma = \left \{(\xi, \eta, \zeta) : \xi^{2} + \eta^{2} + (\zeta - \frac{1}{2})^{2} = \frac{1}{4} \right \} $$  To take a point from $ \mathbb{C} $ to $ \Sigma $ we can use the following:  $$ \xi = \frac{x}{x^{2} + y^{2} + 1}; \eta = \frac{y}{x^{2} + y^{2} + 1}; \zeta = \frac{x^{2} + y^{2}}{x^{2} + y^{2} + 1} $$  We define a circle on $ \Sigma $ to be the intersection of a plane of the form $ A\xi + B\eta + C\zeta = D $ with $ \Sigma $. We also know the converse of this problem is true, that the intersection above yeilds a set in $ \mathbb{C} $ with the following property:  $ (C - D)(x^{2} + y^{2}) + Ax + By = D $. As you can see, when C = D, then an equation for a line is yeilded, otherwise it is a circle.   I really am at a  loss about how to solve this problem. The only thing I can think to do is to pick 3 points on a circle or radius $ r $ with center $ z_{0} $, use these points to find two vectors in $ \Sigma $, take their cross product to get a normal vector, use this normal vector to get a plane. Once I have the plane in form $ A\xi + B\eta + C\zeta = D $ then I could prove that the circle I had chosen corresponds exactly with $ (C - D)(x^{2} + y^{2}) + Ax + By = D $. Is there not an easier, less computation way to do this? Model selection with low N? I've got a study which is kinda messed up by the design...Turns out I ended up with about 50 patients of which 80% have the outcome and 20% don't (binary outcome).  I've been turning in my bed for the last month trying to figure out what to do with this. The only real answer is "don't" but I have to deliver something in the next days as it's part of a master's thesis.  I have about 10 predictors of interest for the outcome (various variable types) and the research question is whether any of these predictors can predict the outcome. Some already have an established correlation in the literature while some are original hypothesis. Several are significant with a univariate logistic regression, but it doesn't look good in any other way than the actual p-value.  Now obviously I'm not going to be able to answer this research question sufficiently but if you were in my shoes, what sort of statistical analysis would you perform to relay to your supervisors?  EDIT: Link to my (anonymized) data (CSV): Peltier Unit Not Working On Latin.SE, I am getting a 404 error when clicking any of the three "history" links on the .  That is, this:        Gives this:        All three editable sections have a revision history with two revisions or more, and all three give an error.  The actual links are , , and . Proof that in a field $x=0$ is equivalent to $x=-x$ Why do some font commands behave differently? I've always been confused by the differences in behavior of font commands.  For example, we have \mathrm{} and \texttt{}, which can be used like this: \texttt{hello} world.  And then we have \it and \bf which must be used as {\it hello} world. If one uses \it{hello} world, both words are italicized.  Internally, what is the difference here? And was this difference a conscious design decision? If so, why? How to uncover a table column wise in Latex beamer I have a table with 7 columns and want to show the first 5 at once, and then  the 6th and 7th on consecutive slides.  This is the code I have for now:  \begin{frame}{Наслов}     \begin{itemize}         \item Ставка.     \end{itemize}         \begin{tabular}{ccccc&lt;{\onslide&lt;2-&gt;}c&lt;{\onslide}c}             $p_1$ &amp; $p_2$ &amp; $\ldots$ &amp; $p_{9}$ &amp; $p_{10}$ &amp; $W$  &amp; $D$\\             $1$   &amp; $1$   &amp; $\ldots$ &amp; $1$      &amp; $1$     &amp; $w_1$&amp; $d_1$\\             $1$   &amp; $1$   &amp; $\ldots$ &amp; $1$      &amp; $0$     &amp; $w_2$&amp; $d_2$\\             $1$   &amp; $1$   &amp; $\ldots$ &amp; $0$      &amp; $1$     &amp; $w_3$&amp; $d_3$\\             $1$   &amp; $1$   &amp; $\ldots$ &amp; $0$      &amp; $0$     &amp; $w_4$&amp; $d_4$\\             $\vdots$ &amp; $\vdots$ &amp; $\vdots$ &amp; $\vdots$ &amp; $\vdots$ &amp; $\vdots$ &amp; $\vdots$\\             $0$   &amp; $0$   &amp; $\ldots$ &amp; $0$      &amp; $1$     &amp; $w_{1023}$&amp; $d_{1023}$\\             $1$   &amp; $1$   &amp; $\ldots$ &amp; $0$      &amp; $0$     &amp; $w_{1024}$&amp; $d_{1024}$         \end{tabular} \end{frame}   This produces 2 slides: the first one with p1, p2, ..., p9, p10 and D columns, and the second with W added, while I want them to appear in the following order:   1st slide: p1, p2, ..., p9, p10  2nd slide: p1, p2, ..., p9, p10, W 3rd slide: p1, p2, ..., p9, p10, W, D   I looked in the manual and found this example:  \begin{frame}     \begin{tabular}{l!{\vrule}c&lt;{\onslide&lt;2-&gt;}c&lt;{\onslide&lt;3-&gt;}c&lt;{\onslide&lt;4-&gt;}c&lt;{\onslide}c}     Class &amp; A &amp; B &amp; C &amp; D \\     217     X &amp; 1 &amp; 2 &amp; 3 &amp; 4 \\     Y &amp; 3 &amp; 4 &amp; 5 &amp; 6 \\     Z &amp; 5 &amp; 6 &amp; 7 &amp; 8     \end{tabular} \end{frame}   which does what is supposed to. However, I don't seem to be able to apply its logic to my problem. :( Is anyone willing to help?   P.S. What are the meanings of &lt; and ! in columns specification? Long lay over in Seoul. Do I need a visa as a Filipino citizen? I'm a Filipino immigrant from USA about to visit home in December.  I have a 14-hour lay over in Seoul,  South Korea.  Do I need a visa to leave the airport to do a little sightseeing? 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. Run Ubuntu ISO live image from Windows BIOS - no USB or DVD An integrable and periodic function $f(x)$ satisfies $\int_{0}^{T}f(x)dx=\int_{a}^{a+T}f(x)dx$. I want to prove:     For an integrable function $f(x)$ and periodic with period $T$, for every $a \in \mathbb{R}$, $$\int_{0}^{T}f(x)\;dx=\int_{a}^{a+T}f(x)\;dx.$$   I tried to change the values and define $y=a+x$ so that $dy=dx$ and the limits of the integrals are as we want, but I'm not sure how to use the fact that $f(x)$ is periodic.  Thanks a lot! Minecraft Inventory Saving I have been attempting to solve this integral for several days in preparation for an exam and keep reaching dead ends.  I(a,b) = $\int_0^{\pi/2} \ln(a^{2}\cos^2(x)+b^{2}\sin^2(x)) dx$, where $a,b&gt;0$  My best approach so far is defining:  $F(x) = I(x, b)$  Then, I know:  $F(b) = I(b, b) = \pi/2 * \ln(b^2)$  Then I am now attempting to find $F'(x)$ using differentiation under the integral sign, and integrating from b to a.  This is where I am stuck - no matter what I do, I cannot solve the integral. Am I in the right direction or should this be solved in a different manner? I also considered something elliptical due to the acos, bsin in the original integral, yet it has also reached a dead end. What is the meaning of the term "linear" How to hide a(n) (NTFS) partition from ubuntu I need to hide an NTFS partition from listing in the nautilus. How can I achieve that?   Is there any tool to do that?   And how can I hide files in ubuntu (except . operator) Whenever I want to use the pipe operator in the terminal, I get a weird kind of "bug":    As is shown in the image above, I can type the exact same command twice and it will sometimes register it or sometimes include some spacing in the command, as can be seen in the error message. The only difference between the two commands was the speed I typed them, with fast typing the char sequence "| " (without the "") leading to the error. I've checked in the terminal settings if this sequence somehow triggers a shortcut, but I did not find anything.   In case it matters, I'm using a swiss keyboard. The layout is as follows:    To produce the "|" character, I press "alt + 7". Does anybody know what the cause of this problem is? How do I resolve "WILL_NOT_PERFORM" MS AD reply when trying to change password in scala w/ the unboundid LDAP SDK?