Find files that contain a string and do not contain another
How to find files that contain one criterion but exclude a different criterion
I just enabled the Blenderkit addon but cannot seem to figure out how to edit the objects. I looked in this reddit thread and amazingly none of the solutions worked for me.  Making it a single user object, data, and materials did not work. I do not see any option to append when adding a model form the Blenderkit asset bar (I even tried saving it and appending the object in another instance of Blender and it still would not let me edit it). And when I right click I do not see an option to make local on outliner collection. I am using Blender 2.83 if that makes a difference but can use 2.9 if need be. Any other solutions? This is exercise 1.6.1 of   Suppose that 501 distinct integers are selected from 1 . . . 1000. Show that there are distinct selected integers $a$ and $b$ such that $a | b$. Show that this is not always true if 500 integers are selected.  This seems like it should be simple but it's has been stumping me for a few days.  Here's my idea for a proof:  Let $S$ be a set of 500 distinct integers between 1 and 1000 that don't divide each other. Let $S_{1-500}$ and $S_{501-1000}$ partition $S$ into sets containing the elements ≤ and > than 500, respectively. Then consider $2 S_{1-500}$ and $\frac{1}{2}S_{501-1000}$, the result of multiplying the elements of these sets by 2 and 1/2, respectively. Because elements of S are coprime, $S_{1-500}$, $S_{501-1000}$, $2 S_{1-500}$, and $\frac{1}{2}S_{501-1000}$, are disjoint. Also note that each of these sets is a subset of the integers from 1 to 1000. One can deduce that the cardinality of the union of these sets is 1000, and therefore they form a partition of the integers from 1 to 1000.  Now, I know this demonstrates that you can't add another number to $S$ that is coprime with all the elements in $S$, which means that a coprime subset of the integers from 1 to 1000 can have at most 500 elements. Can someone articulate why this is true for me? Also, this was in a section on the Pigeonhole principle, can someone rework the proof to utilize that, and possibly make it simpler? Thanks. Here, we suppose that $x,y\in\mathbb{R}$ and that $x^n=y^n$, where $n$ is odd. I want to prove that $x=y$.  Maybe we can use that $x^n-y^n=(x-y)(x^{n-1}+x^{n-2}y+...+xy^{n-2}+y^{n-1})$  So, it suffices to show that if $x^n=y^n$ then $x^{n-1}+x^{n-2}y+...+xy^{n-2}+y^{n-1}\neq 0$  Any hint? Create JSON using apex I am working with dimensionality reduction algorithms. Linear Discriminant Analysis (LDA) is a supervised algorithm that takes into account the class label (which is not the case of PCA for example). I am using Python to do a comparative study between some algorithms.  Why with two classes (k = 2), regardless of the data dimensionality, LDA gives one dimension, i.e. the new subspace is composed of only one dimension? For example if I try to project my dataset (of 100 attributes and 2 classes) to 10-dimensional space by using LDA(n_components=10) I only obtain 1 dimension?  For k&gt;2 I can obtain the number of discriminant vectors that I specified as n_components. How can I get n_components dimensions for k=2? Just like if we have any quadratic equation which has complex roots, then we are not able to factorize it easily. So we apply quadratic formula and get the roots.  Similarly if we have a cubic equation which has two complex roots (which we know conjugate of each other) and one fractional root, then we are not able to find its first root by hit &amp; trial.  So my question is like quadratic formula, is there exist any thing like cubic formula which help in solving cubic equations?  For example, I have an equation $$2x^3+9x^2+9x-7=0\tag{1}$$ and I have to find its solution which I am not able to find because it has no integral solution. Its solutions are $\dfrac {1}{2}$, $\dfrac{-5\pm \sqrt{3}i}{2} $, I know these solutions because this equation is generated by myself.  So how can I solve equations like these?  Also while typing this question, I thought about the derivation of quadratic formula, which is derived by completing the square method.  So I tried to apply ‘completing the cube’ method on the general equation $ax^3+bx^2+cx+d=0$ but it didn't help.  So please help me in finding a cubic formula or to solve the equations like given in example by an alternative method. Why $(a+d)(b+c)$ equals $-16$? If $a,b,c$ and $d$ satisfy the equations:$$a+7b+3c+5d=0$$$$8a+4b+6c+2d=-16$$$$2a+6b+4c+8d=16$$$$5a+3b+7c+d=-16$$ then $(a+d)(b+c)$ equals $-16$.   I can't understand why $(a+d)(b+c)$ equals $-16$? Is there an injective function $f :\mathbb{R}^2\rightarrow\mathbb{R}$?  I approached this problem from the perspective of $f^{-1}$, from which I showed there exists a surjective function $f^{-1}:\mathbb{R}\rightarrow\mathbb{R}^2$. Would this imply that there exists an injective function for the inverse mapping? In the answer , the parser breaks my URL link.  The URL was with __word__:      http://www.open-mpi.de/projects/hwloc/doc/v1.2/group__hwlocality__membinding.php#gade5e2c28ea8475a479bf2b1df36c6ccd   After parsing, it becomes (&lt;a href is broken; no clickable link):  hwlocality_membinding.php#gade5e2c28ea8475a479bf2b1df36c6ccd"&gt;http://www.open-mpi.de/projects/hwloc/doc/v1.2/group_hwlocality_membinding.php#gade5e2c28ea8475a479bf2b1df36c6ccd   Short test:  http://example.com/_test_ -> test"&gt;http://example.com/test  Or if I put in a naked URL with _test_ just here: Email SMTP validator I need to send hundreds of newsletters, but would like to check first if email exists on server. It's called  validation, at least I think so, based on my research on Internet.    There's several libraries that can do that, and also a page with open-source code in  (), but I have hard time reading ASP Classic, and it seems that it uses some third-party library...    Is there some code for SMTP validation in C#, and/or general explanation of how it works? Absolutely continuity and Lipschitz-like continuity I'm trying to figure out if the following is true or false:  Let $\mu$ and $\nu$ be finite measures on Borel subsets of $[0,1]$,and $\nu \ll \mu$ ($\nu$ is absolutely cts with respect to $\mu$). Does there exist always a $C \in \mathbb{R}$ such that $\forall A \subseteq [0,1]$ that is Borel, we have $\nu(A)$ $\lt$ $C \mu (A)$.  The Radon-Nykodym theorem seems to almost suggest that is true, if I knew it was bounded, then I could say $\nu (A) \le \int_{A} g \ d\mu \le \int_{A} C \ d\mu \le C\mu (A)$, where $C$ is the bound. However, I don't know if it is bounded and in fact, I could take an unbounded function that is still integrable on $[0,1]$, such as $\frac{1}{\sqrt x}$.  I can't even be sure if it is true or false.   Thank you! The Raspberry Pi B+ models have a protection circuit between the USB connector and the 5V net on the board.  They recommend putting a similar protection circuity on a Pi HAT before 'backpowering' the pi through its GPIO header along with a polyfuse.  I understand why this is the recommendation, but I'd like to understand more about how this circuit works.  I did some searching before posting this question and found information on using a MOSFET as a low voltage drop diode, but they all had the gate wired directly to ground without the pair of PNP's and the resistors.  What are they doing for this circuit?  Also, is this primarily using the body diode?  In which case, what's the relevant info on the datasheet that qualifies DMG2305UX for this application?  In the other circuits I found, it appeared low Rdson and Vgsth compatible with the circuit seemed like the relevant characteristics. Why is there such a big difference between "Size" and "Size on disk"? Omitting "is", like in "I think it strange" What is the grammar behind the construction "I think it strange/necessary that ...", and when can and cannot this apparent omission of the copula be used? Do we always need the "that" clause?  Also, this seems to be only allowed when the object is a pronoun (it in the above example). That is, we don't say "I think this method strange", correct? Adding holes simultaneously within mesh Should we write “allow” or ”allows” in “require that the class allow[s]”? Can you explain to me whether I should or should not use ‑s at the end of the  verb allow in this sentence?     This function requires that the container class allow[s] random access   The sentence in the book I read wrote allow without ‑s. However, the container class is a third-person singular, so the ‑s must be required. Is that right? Environments are allowed to have arguments, but reference to those arguments can only appear in the opening code of the environment, and not the closing code.  What is the reason for this, and are there preferred ways around it?  e.g.  \newenvironment{foo}[1]% {some code #1} % allowed {some code #1} % not allowed How do I quickly rename a MySQL database (change schema name)? The MySQL manual at  covers this.  Usually I just dump the database and reimport it with a new name. This is not an option for very big databases. Apparently RENAME {DATABASE | SCHEMA} db_name TO new_db_name; .  This needs to work with , which stores things very differently than . Finding out which app is using the webcam Yesterday I was working on my laptop. Suddenly I noticed that the indicator light of the webcam was on, despite the fact that I wasn't making a video call or using the webcam in any other way at the moment.  It freaked me out.  It freaked me out that some unknown application on my computer was using my webcam without my permission, and possibly sending that video stream to god knows where on the Internet.  In the end, it turned out to be Skype which was in the process of crashing. (Despite me making no calls at the time.) So that story ended well.  But next time I see the webcam indicator light, I want to be ready. I want to be able to know exactly which app is using the webcam so I could destroy it.  Does anyone know how I can find out which app is using the webcam?  (I'm on Windows XP.) Sometimes after I fry something, I wash it immediately in water because it's a bit easier to wash (before the remains stick to the pan).  Does this damage the pan in any way?