Usage Scenarios for Auto Encoders as alternatives to PCA Is there ever a practical situation where one would use a linear autoencoder over PCA?
What're the differences between PCA and autoencoder? Both PCA and autoencoder can do demension reduction, so what are the difference between them? In what situation I should use one over another?
Are the following two sentences correct?     I want you to go to sleep.   and     I want you going to sleep.   If they are both correct, what's the difference? BibTeX: Abbreviate first name (aka given name) to 2 or 3 letters (not 1) Are enemies with immunity to the Poisoned condition unaffected by Contagion? After the , the spell  now inflicts the  condition upon a successful melee spell attack. The relevant spell text is below, with updated portions highlighted in bold:  Your touch inflicts disease. Make a melee spell attack against a creature within your reach. On a hit, the target is poisoned. At the end of each of the poisoned target's turns, the target must make a Constitution saving throw. If the target succeeds on three of these saves, it is no longer poisoned, and the spell ends. If the target fails three of these saves, the target is no longer poisoned, but choose one of the diseases below. The target is subjected to the chosen disease for the spell's duration. Since this spell induces a natural disease in its target, any effect that removes a disease or otherwise ameliorates a disease's effects apply to it.  The wording of the spell leads me to conclude that this spell still inflicts a disease, which has the immediate effect of poisoning the target. Therefore, even if a target has poison immunity, they will still make Constitution saves as designated to see if the disease takes effect. However, the line, &quot;At the end of each of the poisoned target's turns...&quot; also leads me to think that an enemy with poison-immunity cannot be the Poisoned target, therefore disallowing the remaining sequence of events. Are targets with immunity to the Poisoned condition therefore immune to contagion? How do I turn on workspaces? (Why do I only have one workspace?) Prove $\mathbb{Z}_2 \times \mathbb{Z}_2$ is not isomorphic to $\mathbb{Z}_4$ In trying to understand why there are two sets of groups of order 4.  I know that there exists the Vierergruppe of $\mathbb{Z}_2 \times \mathbb{Z}_2$ and the group $\mathbb{Z}_4$ but I do not understand why they are not isomorphic How to properly adjust monitor brightness and contrast? I've got a directory shared on my network, using Samba. People on the netwerk use this Samba share to download files from my share to their computers. I'm interested in what files are downloaded most, and by which users they are downloaded. I'd like to see this in real time, if possible. Is there a program that allows me to do this? If yes, how can I use it?    I'm using Ubuntu 11.10. Non-principal ideal in $K[x,y]$? Can't kill a sleeping process What happens if I activate a product key on Steam for a game I already own? I have a Steam product key for Just Cause 2 I got for free with the purchase of my video card. However, I already have a copy of this game attached to my Steam account. What will happen if I try to activate this other key on my account? Will Steam give me a copy of Just Cause 2 to gift to somebody else? Will it simply refuse to add it? Or will it eat the key rendering it worthless?  I don't want to try this only to have the latter happen, but it would be useful to be able to add it and gift it to somebody else. Do I have a virus on my phone? A message from an Android app says so I have just received a message from an Android app on my phone saying my phone has been infected with a virus and to click a link to fix the problem.   I'm not sure I trust this, is it possible to have a virus on Android? Drawing cross section in QGIS? Does anyone have a simple work-flow for drawing cross sections of earth features in QGIS?   My thing is that QGIS is being used to present the plan view, but we have a little interest in some elevations as well. All the data is one set and is simply an elevation value in the attribute table, I don't want to have to move all that to CAD.  One logical workaround is to present the z value as the y.  I am a dunce in paper space in CAD, and would be more comfortable with the QGIS Composer. Is there an easy way to change filetype association? After the upgrade to 11.10 I've had the problems that    all music-files would open with banshee, which then crashed all folders would open with konsole   The first problem I  after installation of "ubuntu tweak" "> admin > filetype Associations".. Changed back to totem.  The second was somehow not accessible this way (did not give any possibility to add commands).  I've changed the line "inode/directory=nautilus-folder-hanlder.desktop" to "inode/directory=nautilus.desktop" from "/usr/share/applications/defaults.list" and now everything works fine.  Question: More convenient ways to do that? Is there anything in Objective-C similar to C# yield return When I get exceptions, it is often from deep within the call stack.  When this happens, more often than not, the actual offending line of code is hidden from me:  tmp.rb:7:in `t': undefined method `bar' for nil:NilClass (NoMethodError)         from tmp.rb:10:in `s'         from tmp.rb:13:in `r'         from tmp.rb:16:in `q'         from tmp.rb:19:in `p'         from tmp.rb:22:in `o'         from tmp.rb:25:in `n'         from tmp.rb:28:in `m'         from tmp.rb:31:in `l'          ... 8 levels...         from tmp.rb:58:in `c'         from tmp.rb:61:in `b'         from tmp.rb:64:in `a'         from tmp.rb:67   That "... 8 levels..." truncation is causing me a great deal of trouble.  I'm not having much success googling for this one:  How do I tell ruby that I want dumps to include the full stack? z-score and Normal Distribution free groups: $F_X\cong F_Y\Rightarrow|X|=|Y|$ I'm reading Grillet's Abstract Algebra. Let $F_X$ denote the free group on the set $X$. I noticed on wiki the claim $$F_X\cong\!\!F_Y\Leftrightarrow|X|=|Y|.$$ How can I prove the right implication (find a bijection $f:X\rightarrow Y$), i.e. that the rank is an invariant of free groups?  I am hoping for a simple and short proof, having all the tools of Grillet at hand. Rotman (Advanced Modern Algebra, p.305) proves it only for $|X|&lt;\infty$, Bogopolski's (Introduction to Group Theory, p.55) proof seems (unnecessarily?) complicated, and Lyndon &amp; Schupp's (Combinatorial Group Theory, p.1) proof I don't yet understand. It's the very first proposition in the book; in the proof, they say:     The subgroup $N$ of $F$ generated by   all squares of elements in $F$ is   normal, and $F/N$ is an elementary   abelian $2$-group of rank $|X|$. (If   $X$ is finite, $|F/N|=2^{|X|}$ finite;   if $|X|$ is infinite, $|F/N|=|X|$). $\square$   Is $N:=\langle w^2;w\in F\rangle$? What is an abelian $2$-group? Elementary? What and how does the above quote really prove? I'm guessing a free abelian group on $X$ is $\langle X|[X,X]\rangle\cong\bigoplus\limits_{x\in X} \mathbb{Z}$?  Can an isomorphism $\varphi:F_X\rightarrow F_Y$ not preserve the length of words? At least one letter words? I want to change the default location of "Save a screenshot to Pictures" to save it to Desktop.   If that is not possible, is there any other way to do it? I am using Ubuntu GNOME 17.04.  NOTE: I don't want to change the location with dconf-editor as it changes the location of screenshot applet and not of the shortcut I require. For gravity, we have    General Relativity, which is a geometric theory for gravitation.  Is there a similar analog for Electromagnetism? Suppose you had a question, and you really want a good answer that would solve your problem, but noticed it was already asked by someone else. However, no one has posted any answers. The question is technically considered "unanswered", but a lot of users who would otherwise bother to give a correct answer probably skip the question completely for some reason.  What should I do in this case?  One idea is to ask a new, completely identical question, in the hope users will notice the new question and post an answer there. But would that go against SE policy?     Note: This is adapted from , but that doesn't cover the case where the original question is unanswered. Also, it is not a duplicate of , as that question asks about getting attention for one's own questions, while this one and the one linked above ask about getting an answer if someone else has already posted the same thing.