Using SFINAE to detect a member function
Templated check for the existence of a class member function?
cardinality of the Borel $\sigma$-algebra of a second countable space Second countability by itself doesn't restrict the cardinality of a topological space, since every set with the trivial topology is a second countable space, but it seems natural to ask whether second countability restricts the cardinality of the Borel $\sigma$-algebra of the space.  Can the cardinality of the Borel $\sigma$-algebra of a second countable space be arbitrarily big? If this is the case is there a simple construction for a second countable space with an arbitrarily big Borel $\sigma$-algebra? I caught an Eevee, which of its evolutions will it evolve into? So I just caught an Eevee. Now, I need 25 candies to evolve it. The fact is that in the GameBoy color versions, that Pokémon needed a stone to evolve instead of experience. Depending of the stone he was fed with (thunder, water or fire), he was evolving in a different Pokémon.   Is the stone feature also in Pokémon Go? If not, what decide the evolution of this Pokémon?   Bonus point : If it's possible, how can I get a stone? Conveniently schedule a command to run later? What's a simple way to run a command, say, 8 hours from now? I can think of this way:  nohup bash -c "sleep 28800 ; ./mycommand.sh" &amp;   Is there a more "proper" way? Recently I paid a lot (almost one month of my salary) for repairing my car. I am wondering if there is a way to get deduction on federal or state taxes (USA, California). How do you create a dropdownlist from an enum in ASP.NET MVC? What tools (ideally affordable ones) would folks recommend for creating a website wireframe? English questions and negation with *do* in syntax I'm getting an error in WSL while trying to use .  I followed all the install steps successfully on Windows 10 x64 using the steps at , then Ubuntu for Windows with GitHub desktop .  But I'm blocked at the latest steps.  It's where I trying to download or train the model in Windows. Using for example the Ubuntu Linux prompt, I navigate manually to the appropriate place and type a following command like the one below (I also tried in su mode)  bash pretrained_models/download_pix2pix_model.sh facades_label2photo   I get an immediate error, always the same, similar to these:  root@Azure:/mnt/c/Users/vincent/Downloads/vision/pytorch-CycleGAN-and-pix2pix# bash pretrained_models/download_pix2pix_model.sh facades_label2photo pretrained_models/download_pix2pix_model.sh: line 2: $'\r': command not found Note: available models are edges2shoes, sat2map, and facades_label2photo pretrained_models/download_pix2pix_model.sh: line 4: $'\r': command not found ]pecified [facades_label2photo pretrained_models/download_pix2pix_model.sh: line 6: $'\r': command not found mkdir: cannot create directory ‘./checkpoints/facades_label2photo\r_pretrained\r’: No such file or directory pretrained_models/download_pix2pix_model.sh: line 10: $'\r': command not found WARNING: timestamping does nothing in combination with -O. See the manual for details.  : No such file or directoryhphoto pretrained_models/download_pix2pix_model.sh: line 12: $'\r': command not found pretrained_models/download_pix2pix_model.sh: line 13: $'\r': command not found   Any idea? Why can't variables be declared in a switch statement? I've always wondered this - why can't you declare variables after a case label in a switch statement?  In C++ you can declare variables pretty much anywhere (and declaring them close to first use is obviously a good thing) but the following still won't work:  switch (val)   {   case VAL:     // This won't work   int newVal = 42;     break; case ANOTHER_VAL:     ...   break; }     The above gives me the following error (MSC):     initialization of 'newVal' is skipped by 'case' label   This seems to be a limitation in other languages too.  Why is this such a problem? The Sharpshooter feat includes an interesting feature: you can choose to take -5 penalty to hit with a ranged weapon attack to increase its damage by 10. Normally, I'd dismiss the trade-off as too situational, but I've only just thought of combining it with the Archery fighting style (+2 to hit with ranged weapon attacks).  After building a sample character using these features, the end result looks quite effective. My questions are: Is this build valid? Have I interpreted the rules correctly? If so, how well does it compare against other damage-focused builds?  5th level variant Human Fighter:   Ability Scores (via point buy): Str 10, Dex 16, Con 16, Int 9, Wis 12, Cha 10 HP: 47, AC: 17 (or 18 with disadvantage on Stealth) Weapons: Hand Crossbow x 2 Fighting Style: Archery Martial Archetype: Battle Master (with the Precision Attack maneuver) Feat (variant Human): Crossbow Expert Feat (4th level ability score improvement): Sharpshooter   The end result is a fighter capable of hitting targets 120' away, behind 1/2 or 3/4 cover, or engaged in melee with him, all without penalty. Normally, he can make 3 such attacks per round (Attack action + Extra Attack + Crossbow Expert's bonus attack). Once per short rest he can make 5 attacks per round via Action Surge (Attack action 1 + Extra Attack, Attack action 2 + Extra Attack, Crossbow Expert's bonus attack).  His normal attack bonus is +8 (3 proficiency, 3 Dexterity, 2 Archery fighting style), and normal damage is 1d6+3. Not amazing damage, but nice accuracy and flexibility (attacks can be focused on one target, or spread around; works equally well in melee and ranged combat).  The real winner is his ability to take -5 on any of these attack rolls to increase the damage by 10, to an average of 16.5 per shot (excluding crits). If he lands his usual 3 attacks, that's ~47 damage; 5 attacks is ~83. While the -5 to hit seems imposing, he's still got superiority dice: he can increase his attack roll by 1d8 after seeing the result, up to 4 times per short rest. And even without the superiority dice, his attack bonus is still an acceptable +3; ok for hitting low AC targets, or those granting advantage on attack rolls (e.g. surprised or prone + adjacent).  With a decent AC, a Fighter's HP, and the Second Wind feature, he can also take a decent amount of damage. He'll also have decent Strength, Dexterity, and Constitution saving throws.  This build seems almost too well rounded. Unlike a blaster, he only requires short rests to recover his big hitters. Unlike a brawler, he can target just about anything on the field at a moment's notice. Have I missed any rules, or overlooked any drawbacks? Wouldn't it be a good idea to be able to vote for questions to be moved to any Stack Exchange site? For example, I just voted  as off topic, but that was all I could do. I wish I could've voted it be moved to .  It's OK to have the predefined list of sites that is now when voting to move, but it would be nice to have a more link, where we could pick any Stack Exchange site.  Here's a quick mockup of how I see this implemented:    When the more link is clicked, a list of all the Stack Exchange sites should appear. "did shoot" vs "shot" This morning I read this sentence (see ):     On July 24th and again on July 29th,   Egyptian police did shoot dead unarmed   African migrants attempting to cross   that border.   Why "did shoot" and not "shot"? Is it poor form to switch accepted answers? I had a question of the form "does something like X exist?" Someone wrote a response to say that, No, X does not exist, but I could write it if I liked. I had suspected as much, so I marked his answer as the accepted answer. Today someone actually posted the code to do X for me, and I feel that the new poster deserves the "Accepted Answer" checkmark.  Is it poor form for me to pick a new Accepted answer? Does the original answerer get penalized in terms of reputation?  While the original responder's answer was accepted at the time, I feel this new answer is really more helpful.  Edit: Which of these responses should I accept? What does the notion of a single accepted answer mean with a question that is subjective that could have multiple "right" answers? number theory about index Given the congruence $x^3 \equiv a \pmod p$, where $p \geq 5$ is a prime and $\gcd(a,p)=1$, prove the following:   If $p \equiv1 \pmod 6$, then the congruence has either no solutions or three incongruent solutions modulo $p$ If $p \equiv5 \pmod 6$, then the congruence has a unique solution modulo $p$   Help me...  I don't know what I learn because Prof teaches so quickly.  So I need your help to organize my thoughts. Understanding quantum entanglement.. help me validate this analogy! I'm struggling to understand the concept of quantum entanglement. I've distilled my understanding into an analogy, and I need your help to validate it. Here it is:  Let's say I receive two envelopes. Both envelopes have this written on them:     Hello! Open this letter...   If the paper inside is red, then other envelope has blue paper.   If the paper inside is blue, then other envelope has red paper.   So, if I open one letter, and the paper inside is red, then I know the other letter contains the blue paper.  Is this equivalent to quantum entanglement? The fact that I will know the color of the other paper when I open (i.e. observe) one envelope?  In theory, if one of the letters "appeared" in a different galaxy, I would still know the color of the paper inside that letter, just by opening my letter, instantly, correct?  Before I open the letter, is the paper inside each envelope in superposition (??), i.e. 50/50, red or blue?  In this analogy, I am assuming that what's written on the letters is true. Is this a correct assumption in quantum physics? I think so yes?  In real quantum physics, would I be able to change the color of one paper, so that I change the color of the other one? No right? Is using only HTTPS bad in a SEO perspective? I would like to set up a new business site. I plan to direct www.example.com to example.com and only use that domain. My plan is also to only use HTTPS and not HTTP.   Does this affect the SEO for the site? E.g. do Google put lower or higher rank for sites that is only available via HTTPS? How to evaluate the integral $\int \sqrt{1+\sin(x)} dx$ To find:  $$\int \sqrt{1+\sin(x)} dx$$  What I  tried:  I put $\tan(\frac{x}{2}) = t$, using which I got it to:  $$I = 2\int \dfrac{1+t}{(1+t^2)^{\frac{3}{2}}}dt$$  Now I am badly stuck. There seems no way to approach this one. Please give a hint. Also, can we initially to some manipulations on the original integral to make it easy? Thank you. I don't know what exactly it's called, by cache refresh I mean, refresh the page after clearing its cache. I don't want to clear the entire browser cache.  I can't seem to cache refresh my pages. In Firefox, I know it to be Shift+Refresh.  In Chrome, I've tried Ctrl+R, Ctrl+Refresh, Alt+Refresh, Shift+Refresh but none of them work. Is this valid for convergence? Does $\sum_{n=1}^{\infty} \sqrt[n]{3} - 1$ converge or diverge?   Hints please  I have that $0 \le \sqrt[n]{3}  - 1 \le 1$  Does this help? For regression problem, I have seen people use "coefficient of determination" (a.k.a R squared)  to perform model selection, e.g., finding the appropriate penalty coefficient for regularization.   However, it is also common to use "mean squared error" or "root mean squared error" as a measure of regression accuracy.  So what is the main difference between these two? Could they be used interchangeably for "regularization" and "regression" tasks?  And what are the main usage of each in practice, such as in machine learning, data mining tasks?