Why can't you run OS X on a PC?
What are the technical obstacles that doesn't allow OSX to be installed in a PC?
The origin of my question arose from a problem: Let $q: X \to Y$ and $r: Y \to Z$ be covering maps, let $p= r \circ q$. Show that if $r^{-1}(z)$ is finite for each $z \in Z$, then $p$ is a covering map.  I am just wondering is there an easy counter example to show the necessary of "inverse image of every point is finite" condition?  I have already checked Hatcher's book (the wedged circle example) but I wonder is there a less complex and more obvious example?  I tried to construct a counter example by composition of a covering map from $R_+$ to $S^1$ with $R$ in the middle, but I failed due to I can't find a covering map from $R^+$ to $R$ which does the job. In the book , at page 27 we find the exercise asserting that       Exercise I.XXXVI.   The underlying space of a zero-dimensional scheme is discrete; if the scheme is Noetherian, it is finite.     Thoughts I thought that a zero-dimensional scheme is one such that, in every local ring $\mathscr O_{X,p}$, the only prime ideal is its unique maximal ideal $\mathfrak m_{X,p}.$ Hence, supposing that $X=\operatorname{Spec} R$ is affine, we deduce that every prime ideal is maximal, so each ponit in $X$ is closed. But how does this imply the discreteness? It only implies the Hausdorff-ness of $X$, right? Furthermore, I cannot perceive what the "Noetherianity" has to do with the finiteness claimed here. In the affine case, it seems to be claiming that there are only a finite number of prime ideals in a Noetherian ring, if its scheme is zero-dimensional? For example, $\mathbb Z$ is a Dedekind domain, hence its scheme is zero-dimensional, but it has infinitely many primes: does this contradict the statement?    Thanks in advance for any reference or hint, and point out any inappropriate point if any is presented. Edit I see why my example cannot work now: it is one-dimensinoal: don't forget the pirme $(0)$. But I am still wondering why the statement is true... What hardware does Ubuntu Touch support? With the announcement of the Ubuntu Phone OS I'd like to know what phone (and tablet) models are supported at this time.  Note from foss &amp; Oli: We are making this the master question for all future "Will this work on &lt;insert random tablet/phone/device here&gt;?!" questions What is the difference between "source x", ". x" and "./x" in Bash? Using first person or third person in papers? Are there written or unwritten rules for avoiding the use of first-person while writing research papers? I was advised at the beginning of my grad school to avoid use of first person - but I still don't know why I should do this.  I have seen that, at many places, authors refer to themselves are "the authors" and not "we". At the same time, I have also seen use of first-person to a good extent.    Do these things differ in different Journals and Conferences (and in different disciplines as well - mine happens to be CS)? Can I use my powers for good? Blacklight CFL Bulb Effect? I have been searching everywhere, and I can't find an answer so I'm coming here!  I'm trying to create a CFL Blacklight bulb. I've attached a couple images below of what I've tried to make. I'd love to have an effect like this:    Does anyone know how to recreate this? It seems like the color is affected by time as the bulb heats up, eventually being all white-ish. That would be fine, too, but I can't even seem to get the lighting effect of the pink glow around it and whatnot. I can post pictures of my node setup if you need it, though I think I made it necessarily complicated.  Thanks in advance!  UPDATE: This is what I have now:   I want to adjust the colors, but that isn't the issue now... The way I made this is a glass spiral that acts as the bulb. Inside of that bulb (that has a glass-like shader) is a purple material that I made that mimics the phosphor coating blacklight light bulbs have to filter light. Then, a separate mesh spiral is inside of that, and it has the emission stuff on it.   As Duarte suggested, I used the node setup he had for my emission, but used a transparent node instead of glossy. Why isn't the emission light from inside my glass causing the glass to be glossy? If I put a point light in the scene, it looks glossy.   Thanks in advance! Why are neural networks becoming deeper, but not wider? In recent years, convolutional neural networks (or perhaps deep neural networks in general) have become deeper and deeper, with state-of-the-art networks going from 7 layers () to 1000 layers ( in the space of 4 years. The reason behind the boost in performance from a deeper network, is that a more complex, non-linear function can be learned. Given sufficient training data, this enables the networks to more easily discriminate between different classes.  However, the trend seems to not have followed with the number of parameters in each layer. For example, the number of feature maps in the convolutional layers, or the number of nodes in the fully-connected layers, has remained roughly the same and is still relatively small in magnitude, despite the large increase in the number of layers. From my intuition though, it would seem that increasing the number of parameters per layer would give each layer a richer source of data from which to learn its non-linear function; but this idea seems to have been overlooked in favour of simply adding more layers, each with a small number of parameters.  So whilst networks have become "deeper", they have not become "wider". Why is this? Are there naturally occurring lasers? Uneven movement on camera following a path. I render a short movie. I set the camera to the circle curve to make it fly in circle. The problem is after render, the camera is a little shaky. Can anyone help me? Thanks first. Height of colorbox Word for person who looks for flattery Often assignments (or even papers) have a word count limit. That is not a big deal when using Word, but I don't know how to do that using LaTeX. My solution has been so far to compile the document and then do a rough word count of my pdf file, sometimes even copying the contents of the pdf file and pasting in Word to get a mostly correct Word count.  Is there any tool (maybe even an online tool), package, script or software to do that directly from my .tex document and still get the right word count (i.e., ignore commands, equations, etc)? How to show that a set of discontinuous points of an increasing function is at most countable I would like to prove the following:       Let $g$ be a monotone increasing function on $[0,1]$. Then the set of points where $g$ is not continuous is at most countable.     My attempt:    Let $g(x^-)~,g(x^+)$ denote the left and right hand limits of $g$ respectively. Let $A$ be the set of points where $g$ is not continuous. Then for any $x\in A$, there is a rational, say, $f(x)$ such that $g(x^-)\lt f(x)\lt g(x^+)$. For $x_1\lt x_2$, we have that $g(x_1^+)\leq g(x_2^-)$. Thus $f(x_1)\neq f(x_2)$ if $x_1\neq x_2$. This shows an injection between $A$ and a subset of the rationals. Since the rationals are countable, $A$ is countable, being a subset of a countable set.    Is my work okay? Are there better/cleaner ways of approaching it? How can I run Windows applications on a MacBook Pro? I have a friend that wants to buy a Mac Book Pro and he has some windows applications that he needs to run. He doesn't want to buy the applications again.  Can he run the Windows applications on his MacBook Pro? What ways to accomplish this are available? Get list of all tables in Oracle? What are the rules of parallelism? I've been reading a lot about it since yesterday and all I encounter is "They must have the same grammatical form"? What does this exactly mean?  I know how to make parallel sentences with gerunds. The things get trickier when it comes to using modifiers.  For example:     I love using the phone that you bought me and the computer.   On the left side of the conjunction there is a noun phrase that consists of an article + noun + another modifier and on the right side there is an article + noun.  They are both noun phrases but the first one has additional modifier. Is that still considered a parallel sentence?  Another example:     I like to swim and to feel good.   Here on the right side of the conjunction there is an infinitive and on the left side there is an infinitive + complement? Is that parallel? I am making a test where I am asked to add the missing words.     [...] chair is [...] useful piece of furniture.    I would have said that a is the missing word in both the cases, but the test says the words I should have added are the and a respectively.     [...] last time I saw [...] bear, I was travelling in [...] Europe.   I would have added: nothing, a, nothing. The correct answer is: the, a, nothing.  Why is the the correct article to use in both the sentences? I have recently upgraded my OS to Ubuntu 18.04 (fresh install via boot device). However, when trying the command:  sudo apt-get upgrade   It works fine until ~75% when it stops and says:  snapd.snap-repair.service is a disabled or a static unit, not starting it.   I'm not quite sure what this means and if I Crtl-Z to get out of it, any time I try to install anything I get:  E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable) E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?   and have to restart my computer to install anything. Very large log files, what should I do?