I'm a newbie, and I've installed the restricted extras package but I still cant play a dvd. Is there a way to trouble shoot the problem or is there any important codecs that I've missed?
My machine can't play encrypted DVDs on a fresh install.  How do I add this capability?  Another useful bit of information would be what programs are best for playing DVDs, once I'm able to do so.  See the .  Will I be able to play DVD movies from ?
change folder icons in ubuntu-mono-dark theme Textbook on the Geometry of Special Relativity I am looking for a textbook that treats the subject of Special Relativity from a geometric point of view, i.e. a textbook that introduces the theory right from the start in terms of 4-vectors and Minkowski tensors, instead of the more traditional "beginners" approach. Would anyone have a recommendation for such a textbook ?  I already have decent knowledge of the physics and maths of both SR and GR ( including vector and tensor calculus ), but would like to take a step back and expand and broaden my intuition of the geometry underlying SR, as described by 4-vectors and tensors. What I do not need is another "and here is the formula for time dilation..." type of text, of which there are thousands out there, but something much more geometric and in-depth.  Thanks in advance. Fantasy novel: magic school, talking rabbit, character bites off another character's fingers The plotline as a whole is completely lost to me, but it was a big inspiration to my preteen self at the time and has shaped my creative development up to now. I'll list some of the big points that I can recall from it, if anyone has the vaguest idea what book I am referring to I would be so appreciative for any guess! I just want to reread it.   Main character is a delinquent of sorts, goes to a magic school. I don't remember there being any pictures in this book. There is a threesome between the main character and his two friends I believe it is a talking rabbit that says something along the lines of "My dear child, you are incensed", followed by one of the characters saying something like "Damn right I am!" A character that had been mentioned earlier but never made an appearance (he was banned for doing bad magic I think) shows up to fight and he bites off another character's fingers. Main character seeks out a magical white stag near the end of the novel because the stag can grant a wish if it's caught because he wishes to reset his timeline. The stag is able to speak. I have a simple skull model, to which I applied the subdivision modifier. For the most part everything works as expected, except I keep getting these weird sharp vertices and I can't seem to figure out how to flatten them.    I'm using Blender 2.8. Is this some kind of feature I can disable/enable for particular vertices? The distance between the sharp vertices and the gray outline differ.    Any suggestions please? Thank you!  EDIT: I also tried selecting as both - vertexes and edges and then applied Edge->Clear Sharp, but nothing changed. How do you refer to a hyponym that is the same word as the hypernym? What word (or how do you phrase things) do you use when the ostensible word for the class is the same as the word for a subset of the class?  For example, in the United States, there are many brands of sugared, carbonated soft drink that one can buy: Coca-Cola (or Coke), Pepsi, RC Cola, Sprite, 7-Up, A&amp;W or Mug Root Beer, etc). The first two are kinds of 'coke' or 'cola' (but no one says 'cola').  , one asks for any type of such drink as 'coke'. How does one then ask for the particular kind of 'coke' that is 'Coke' (pronounced the same)? Does one reduplicate and say a 'Coke coke', does one repeat with emphasis (or without), does one use a different word like 'coca-cola' (co-cola), or what?  The (perceived) difficulty (surely those in the South are able to get the drink they want somehow) isn't limited to there. Where the drink is called 'soda', if you ask for a 'coke', you'll still sometimes have the choice among Coca-Cola, Pepsi, etc. "Can I have a Coke?" the response might be "Is Pepsi OK?". "Sure, Pepsi, Coke, whatever." You don't use 'cola', you just ask for the particular kind and hope the listener will help differentiate.   Given these multiple strategies for disambiguating, what do you do say to get a 'Coke' in the southern US? are there any other examples of a hypernym being the same as the hyponym, and so creating a disambiguation problem? Why do newspaper headlines use strange syntax rules? Newspaper/news article headlines usually have different syntax rules, for example   No copula. North Korea trip 'successful' Past events written in present. Qantas cancels flight out of frozen Heathrow Predictions written with infinitive. Britain's 'crossbow cannibal' to die in jail Very often not in complete sentence. No indefinite/definite articles. Ivory Coast Faction Squeezes UN Force Using a comma instead of "and". Romania, Bulgaria face delay in joining Schengen.   Why these rules and are there any other rules? An  can be identified by its  together with isolating intervals with rational bounds for its real and imaginary parts. The degree of an algebraic number is the  of its minimal polynomial. There are known algorithms that allow to easily compute sum and product of algebraic numbers in this representation, raise them to a rational power, extract real and imaginary parts, compare them, or evaluate them numerically to an arbitrary precision.  Is there an efficient algorithm that given an algebraic number $\alpha$ in this representation can decide if $\alpha$ can be represented as a sum or product of algebraic numbers of smaller degree? How can I create a new extensible symbol? Given an arbitrary thin vertical symbol, can I create a new math delimiter from it (and if so, how)?   Edit: Ideally, I would like to be able to create an extensible symbol, either built out an existing normal symbol, or even made from scratch.  Edit 2: I am pretty sure that what I am after is an explanation of how to create a .tfm file for an extensible symbol (which Werner's answer describes the general structure of, but not how to make one).    For example, let's say I wanted to use the \dagger () or \wr () symbol as a delimiter, and write expressions like    \[\left\ldagger \sum_{n=1}^\infty a_n \right\rdagger\]   where the symbol scaled appropriately. Would there be any distinction between declaring a symmetric delimiter (like \vert), as opposed to one that has inherently different "left" and "right" versions like [ and ]?  Now, even being unaware of the inner workings of TeX, I imagine that there has to be lots of information in the fonts for how a delimiter is to be scaled in different situations, and if I try to make my own delimiter, this information won't be present. Would I need to get deep into FontForge or equivalent to achieve my custom delimiters, or is there an easier way? I have run a multiple linear regression using stepwise regression to select the best model, however the best model returned has a non-significant variable. When I remove this the AIC value goes up indicating the model without the significant variable is a worse fit. Should I remove the non-significant predictor or should I leave it in as it is a better model? Is the graviton hypothetical? CSS two divs next to each other Persistent live drive with a partition for persistence There are some web sites describing  new tools new features in [new versions of] old tools  that can create a persistent live drive from an iso file with Ubuntu 19.10 and the corresponding Ubuntu family flavours.  Why and how does it work? How is it different from earlier methods for persistent live drives? Isn't live the default for a cloned drive? Use of 'const' for function parameters I started to read about Diffie-Hellman exchange and I encountered a problem which I don't know how to solve.  Given $g=3$, $p=131$, $g^x\bmod p=112$, $g^y\bmod p=74$, compute $g^{xy}\bmod p$   $113$ $110$ $112$ $111$   How could I compute $g^{xy} \bmod p$? Or at least verify which one is correct. Any idea? Show that $\mathbb{R}^{\mathbb{R}} = U_{e} \oplus U_{o}$ A function $f : \mathbb{R} \rightarrow \mathbb{R}$ is called even if $f(-x) = f(x)$ $ \forall x \in \mathbb{R}  $   A function $f : \mathbb{R} \rightarrow \mathbb{R}$ is called odd if $f(-x) = -f(x)$ $ \forall x \in \mathbb{R}  $   Let $U_{e}$ denote the set of real-valued even functions on $\mathbb{R}$ and let $U_{o}$ denote the set of real valued odd functions on $\mathbb{R}$.   Show that $\mathbb{R}^{\mathbb{R}} = U_{e} \oplus U_{o}$   This question from Q24 of "Linear Algebra Done Right" 3rd Edition - Chp 1.4 (Subspaces). The author of the book does minimal work with functions during the chapter. I have no idea how to approach the question. Problems in Creating InfoWindow on each individual circle with mouseover using Google Map API Does a filament of lamp still have resistance when no current flows, and if yes, why? Does a filament lamp still have resistance when no current flows? Read it in the 90's. I remember one specific part where the inventor of the peeking mechanic has his Eureka moment, and has the presence of mind to give a thumbs-up/wave to the future, when they look back on his Eureka moment.  I also remember that they had computer screens that were like plastic cloth that they would just unfold on whatever surface was handy.  Sorry I don't have much more to go on.  Please and thank you! Probability distribution in the coupon collector's problem How is MSE divided by $\sigma^2$ always a chi-square distribution?