Is there a name for artifacts for taking a photo of LCD / LED screens and how to remove or avoid it? The following is a photo of a game console 3DS, although the 3D is turned off:    There is "fish nest" artifacts, and sometimes the lines even curve on some photos.  iPhotos on a Mac seems to try to minimize its effect, but if the window is being resized, the fish nest can change shape along the way of the resize, and then its effect is minimized once the resizing is done.  Is there a name for such artifacts, and are there ways to avoid it and/or correct it if that's the only photo you have?
What is moiré? How can we avoid it? What is the image defect called "moiré"? What causes it, and how can we avoid or reduce it? Is it related to "false color"?
What is cool about generics, why use them? I thought I'd offer this softball to whomever would like to hit it out of the park. What are generics, what are the advantages of generics, why, where, how should I use them? Please keep it fairly basic. Thanks. Do stone quarries respawn in Hearthfire? This came up in  , but I can't see good documentation or examples that explain how the feature works. does not appear to actually define what a rigid shape is. Rather it defines 'same shape' and 'rigid transformations' without giving any definitions of what is necessary and sufficient for a shape to be considered rigid.  For instance, I've seen the following image:    I understand intuitively why the triangle is rigid and quadrilateral is non-rigid. It is also my understanding that inserting a single diagonal connection into the quadrilateral would make the shape rigid? However, given the following image (labeling the shapes $S_1$, $S_2$ and $S_3$ in sequence left to right):    If $S_1$ had a single diagonal connection AB, it would be possible to flip ADB over axis q to obtain a shape similar to $S_2$ with the addition of connection AB (my explanation may not be the greatest). This shape is clearly not the same as $S_1$, so how can we say $S_1$ with a single diagonal connection CD is rigid? I feel I am unclear on what the definition of rigidity actually is. Let $x\in \mathbb{R}$ an irrational number. Define $X=\{nx-\lfloor nx\rfloor: n\in \mathbb{N}\}$. Prove that $X$ is dense on $[0,1)$.    Can anyone give some hint to solve this problem? I tried contradiction but could not reach a proof.  I spend part of the day studying this question   and its answers. Only one answer is clear and give clues to solve the problem. This answer is the first one. However, this answer does not answer the question nor directly, nor the proof follows from this answer.   This answer has some mistakes, he use that $[(k_1-k_2)\alpha]=[k_1\alpha]-[k_2\alpha]$ which is not true. Consider $k_1=3, k_2=1, \alpha=\sqrt{2}$ we have $[(k_1-k_2)\alpha]=2\not= 3=[k_1\alpha]-[k_2\alpha] $. We only can assure that $[k_2\alpha]-[k_1\alpha]-1\leq [(k_2-k_1)\alpha]\leq[k_2\alpha]-[k_1\alpha]$.   Who answered said something interesting about additive subgroups of $\mathbb{R}$, but unfortunately the set $X=\{nx-[nx] : n\in \mathbb{N} \}$ is not a subgroup. Considering the additive subgroup $G=\langle X \rangle$, if we prove the part (a) of the link, we get that indeed $G$ is dense on $\mathbb{R}$ but we can not conclude that $X$ is dense on $[0,1)$.  I think this problem has not been solved.  Thanks! Over the past couple of days there have been a few questions about overlapping proposals and questions that could belong on multiple sites:        What is the best practice before / after asking a question if you think your question might be better on another site?  or  If I think my question might belong on multiple sites as per the above posts? I am asked to determine if a series converges or not:  $$\displaystyle\sum\limits_{n=1}^{\infty} \frac{(2^n)n!}{(n^n)}$$  So I'm using the $n$th root test and came up with $\lim_{n \to {\infty}}\frac{2}{n}\times(\sqrt[n]{n!})$ I know that the limit of $\frac{2}{n}$ goes to $0$ when $n$ goes to infinity but what about the $(\sqrt[n]{n!})$? How do you make a deep copy of an object? It's a bit difficult to implement a deep object copy function. What steps you take to ensure the original object and the cloned one share no reference? I just noticed . Hey! I'm there! But that's beside the point.  The point is that Nick Craver is there too. Nick seems to like really long tag names, so his profile shows up like this:    Akk! Diamonds everywhere!  It seems that the page is optimized for only two lines of tags per user. One tag per line means three lines. Three lines means that Nick's reputation (tag) is cut in half.  Let's not cut Nick's rep (tag) in half on the Users page, no? Is reusing old code for a new assignment considered self plagiarism? How to protect yourself if you consider it to be, and a group partner does not? Why Java needs Serializable interface? Best answer versus best solution A novel where a woman from "future" of 1999 speaks leet-speak "Neither Michael nor Albert is correct" or "Neither Michael nor Albert are correct"? What is the correct sentence?  Neither Michael nor Albert is correct.   Neither Michael nor Albert are correct. Can I use set instead of List to resolve the duplicate id issue If you take a look into this issue     I have provide an answer of using set&lt;Sobject&gt; instead using list&lt;Sobject&gt;  i.e.  if( !contacts.values().isEmpty() ){   set&lt;Contact&gt; setContacts = new set&lt;Contact&gt;();   for( Contact objCon : contacts.values() ){     if(!setContacts.contains(objCon)){         setContacts.add( objCon );     }   }  update new list&lt;Contact&gt;(setContacts); }   even if(!setContacts.contains(objCon)) is not needed  if( !contacts.values().isEmpty() ){   set&lt;Contact&gt; setContacts = new set&lt;Contact&gt;();   for( Contact objCon : contacts.values() ){         setContacts.add( objCon );   }  update new list&lt;Contact&gt;(setContacts); }   So is there any condition/use case where this answer might fail? I've noticed something while trying to prove the properties of parallel lines, and the properties that a triangle has 180 degrees. To prove the properties of parallel lines, such as alternate angles, you need to use the property that a triangle has 180 degrees. To prove a triangle has 180 degrees however, you need to use the properties of parallel lines. This really bothers me because of how circular it is. They are both reliant on each other to be true, and do not logically show, without being reliant on each other, why triangles have 180 degrees, and why parallel line properties are true.   So what I hoping for here is a way to prove parallel line properties without using the fact that a triangle has 180 degrees, or a way to prove triangles have 180 degrees without using parallel line properties. This way, things will be logical to me, and make sense.   Thanks in advance. Java's Virtual Machine and CLR As a sort of follow up to the question called , what is the (major) differences or similarity in how the Java Virtual Machine works versus how the .NET Framework Common Language Runtime (CLR) works?  Also, is the .NET framework CLR a "virtual machine" or does it not have the attributes of a virtual machine? Proof that for $a,b,c\in \mathbb{R}$, hold that $\left |\sqrt {a^2+b^2}-\sqrt {a^2+c^2} \right |\leq \left |b-c \right |$. Proof that for $a,b,c\in \mathbb{R}$, hold that $\left |\sqrt {a^2+b^2}-\sqrt {a^2+c^2}  \right |\leq \left |b-c  \right |$. Give me a clue, I don't have any idea to work with that inequality. What is the best way to solve modular arithmetic equations such as $9x \equiv 33 \pmod{43}$? What is the best way to solve equations like the following:  $9x \equiv 33 \pmod{43}$  The only way I know would be to try all multiples of $43$ and $9$ and compare until I get $33$ for the remainder.  Is there a more efficient way ?   Help would be greatly appreciated! "POSSIBLE BREAK-IN ATTEMPT!" in /var/log/secure — what does this mean? I've got a CentOS 5.x box running on a VPS platform. My VPS host misinterpreted a support inquiry I had about connectivity and effectively flushed some iptables rules.  This resulted in ssh listening on the standard port and acknowledging port connectivity tests. Annoying.   The good news is that I require SSH Authorized keys.  As far as I can tell, I don't think there was any successful breach.  I'm still very concerned about what I'm seeing in /var/log/secure though:     Apr 10 06:39:27 echo sshd[22297]: reverse mapping checking getaddrinfo for 222-237-78-139.tongkni.co.kr failed - POSSIBLE BREAK-IN ATTEMPT! Apr 10 13:39:27 echo sshd[22298]: Received disconnect from 222.237.78.139: 11: Bye Bye Apr 10 06:39:31 echo sshd[22324]: Invalid user edu1 from 222.237.78.139 Apr 10 06:39:31 echo sshd[22324]: reverse mapping checking getaddrinfo for 222-237-78-139.tongkni.co.kr failed - POSSIBLE BREAK-IN ATTEMPT! Apr 10 13:39:31 echo sshd[22330]: input_userauth_request: invalid user edu1 Apr 10 13:39:31 echo sshd[22330]: Received disconnect from 222.237.78.139: 11: Bye Bye Apr 10 06:39:35 echo sshd[22336]: Invalid user test1 from 222.237.78.139 Apr 10 06:39:35 echo sshd[22336]: reverse mapping checking getaddrinfo for 222-237-78-139.tongkni.co.kr failed - POSSIBLE BREAK-IN ATTEMPT! Apr 10 13:39:35 echo sshd[22338]: input_userauth_request: invalid user test1 Apr 10 13:39:35 echo sshd[22338]: Received disconnect from 222.237.78.139: 11: Bye Bye Apr 10 06:39:39 echo sshd[22377]: Invalid user test from 222.237.78.139 Apr 10 06:39:39 echo sshd[22377]: reverse mapping checking getaddrinfo for 222-237-78-139.tongkni.co.kr failed - POSSIBLE BREAK-IN ATTEMPT! Apr 10 13:39:39 echo sshd[22378]: input_userauth_request: invalid user test Apr 10 13:39:39 echo sshd[22378]: Received disconnect from 222.237.78.139: 11: Bye Bye     What exactly does "POSSIBLE BREAK-IN ATTEMPT" mean?  That it was successful? Or that it didn't like the IP the request was coming from?