So I have an LM358 op-amp with 2 (as far as I'm aware) separate channels. I need to increase gain but also need to have enough current to activate a diode. The problem is that the device (sensor) whose voltage I will be amplifying cannot source enough current to activate the diode. So I would use...

I was watching the cartoon Muzzy In Gondoland when I came across this usage of "Wie geht es Ihnen" at the minute "1:16" : -- Wie geht es Ihnen? ++ Ich bin Prinzessin Sylvia. I thought that "Wie geht es Ihnen?" ment "How are you?" not "Who are you?". Can somebody explain this? Also, when the pri...

According to Villars and Daams [Journal of Alloys and Compounds, 197 (1993) 177] the atomic volume of U is $2.073\times10^{-2}\,\mathrm{nm^3}$, whereas that of Th is much larger, $3.295\times 10^{-2}\,\mathrm{nm^3}$. The external electronic configurations of these atoms are: Th: $[\text{Rn]} 6d^2...

I was trying out an example presented at CppCon that uses lambdas. And to my surprise the program don't compile in gcc and clang(in either C++14 or C++17) but compiles in msvc. This can be verified here. For reference, the example code is as follows: #include <stdio.h> int g = 10; auto kitten =...

I'm trying to estimate an average value of distances to K nearest neighbors. I have two sets of coordinates and I'm trying to estimate the average distance from each point in one set of coordinates to the K nearest neighbors in the other set of coordinates. The following post is instructive in ho...

While rummaging in my molecular model kit, I noticed that it contains a surprising number of $180^\circ$ oxygen atoms, i.e., oxygen that is meant to be covalently bonded to two partners in a linear geometry. Obviously this isn't a hard reference, but since the geometries contained in the kit usua...

I have installed the Google Drive desktop app and it's available on Finder as a mounted drive, but I can't seem to access it from the terminal. For example, when I do cd 'Google Drive' I get a cd: Permission denied: 'Google Drive/' error. This happens even when I have some files stored locally. I...

Suppose a person had the same salary as 2020 and lived in NY and got a refund. Also suppose he lived in PA in 2021 and didn't get a refund? Why would this be the case? I thought PA tax was lower than NY tax?

The question has been asked here seven years ago but unfortunately did not receive an answer perhaps because at that time it would be reasonable to assume that no available dataset might have made it to the web. Now, I have been searching continuously for a light curve dataset for this star conta...

Let $J_n$ be the square matrix of ones (all entries are a one). I want to characterize the "square root" of $J_n$ where the square root is a matrix $A$ such that $A'A=J_n$ and $A$ is $k\times n$. In particular, I think that any such matrix $A$ needs to have all columns be the same. For instance, ...

How do I raise a matrix to the infinite power? I know that the main method for doing this is by diagonalizing the matrix, but what if I can't? For example, let's say I have the matrix \begin{bmatrix}0&0&0&0&0\\2/3&0&0&0&0\\1/3&0&1&0&0\\0&3/7&0&1&0\\0&4/7&0&0&1\end{bmatrix} You can see that when I...

I think this question is a reasonable fit here, but possibly it is better suited to History.se or Skeptics.se, in which case my apologies and please migrate it. 10 Downing Street has recently confirmed that Boris Johnson, the current Prime Minister of the United Kingdom, will be issued a fixed pe...

I'm using Ubuntu. How can I use a private key in an ssh client for only one host? The private key is used for all hosts, every time I connect to any server, the private key authentication is used.

What does "careabouts" mean? I searched all dictionaries but got nothing! I even got nothing on Google! Like such a thing doesn't exist! "Identify his careabouts" for instance. Does it simply refer to things somebody cares about?

I feel stupid for not being able to do this and I think it is just a syntax error. Let's say i have the following list: L={x,xy,x^2+y,xyz,x^2} How do I define 5 functions where each one is simply each polynomial in this list. Naively I would say this should work f[i_][x_,y_,z_]:=L[[i]] But this...

TL;DR: How can you transform the resistance of a light dependent resistor (up to 2MΩ) to an analog signal, so that it reflects the logarithmic growth in resistance as a (more or less) linear output? First of all: Although the relationship between Lux and LDR resistance is indirectly proportional...

Computer Algebra Systems (CAS) are philosophically interesting in that they are an aspect of the long history of treating mind as mechanism. In this respect, mathematics may be thought of as formalizing "mind" and CAS the closest approximation to a mechanical implementation. We routinely encoun...

I'm having an issue with the circuit bellow, it is supposed to be a current limiting circuit but is oscillating. I know probably is an issue with poles and zeros, but with this configuration I'm not really sure what I'm able to do. Anyone has any suggestion of something I could try? Besides chang...

Latte, as in the usage I'd like a latte (example from Cambridge English Empower, 2015) is ubiquitous among English speakers who have visited coffee bars or seen them in film or TV. It means a caffè latte, steamed milk with espresso. Yet latte by itself (what would mean "milk" in Italian) is a f...

Test #1 https://duckduckgo.com/?q=what+is+my+user+agent&ia=answer Says: Your user agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.81 Safari/537.36 Vivaldi/5.2.2623.26 Test #2 https://www.whatismybrowser.com/detect/what-is-my-user-agent/ Sa...

As the Vlocity documentation says, for Integration Procedure Unit Testing from Apex, we must use Salesforce seeAllData property. In my case, the ideal would be to insert Order data for the test unit. Because this Integration Procedure only works for certain records, otherwise an exception will be...

I'm working with multiple animations inside a single Beamer frame, and I wish to include only the last page of a multipage PDF page inside an \only<n>{\includegraphics[opt]{args}}. The problem is that those frame-separated-multipage PDFs have all different total number of pages: I tried \includeg...

I am looking for feature rich calendar app for Linux. Kalendar seems fit the bill. However, I am not able to install it on my Ubuntu system. Clicking on the "Install on Linux" link from the web browser gives me the error Failed to install. Not supported. I am new to Ubuntu and any help will be ap...

Usually, when talking about adverbs of frequency, we put them under the topic of "Simple Present Tense". Because in this tense we consider habits and routines and adverbs of frequency are the most useful phrases that we can describe our routines frequency by. My question is if we can use the adve...

Summary: How to graph a 2D parametric equation using Geometry Nodes? Details: This question asks about plotting 2D functions of the form $y = F(x)$ using Geometry Nodes, and of course the simplest way to do that would be with a node group like this: where the Power math node is replaced by a sel...

I'm stuck on a question about diagonalizability of matrices and need some help moving forward.I think I made some progress but I'm also not sure if its any good. Let $a \in \mathbb{R}$, $A$ is a matrix. For which values of $a$ is the matrix $A$ diagonalizable. $$A:= \begin{pmatrix} 1 & 2 & 3 & 4...

I tried to run v5root.gz on simh V3.8 (unix research version 5). This works in sofar that I get a login-prompt. If I though look at the source code of main.c (line 55) of the kernel in that image, then I see the following: printf("mem = %l\n", maxmem*10/32); I checked in prf.c that printf (...

I'd like to obtain an analytical form for the following definite integral, in which $f$ and $b$ are positive quantities. Integrate[1/( Sqrt[f + b*x^2]), {x, 1, a}] Mathematica is unable to provide an answer directly. Is there another way to obtain an analytical answer?

I have gotten fairly decent for a hobbyist with Blender and I am just starting to get into the geometry nodes. I have played with them but not done anything serious because I am rather stuck on what seems like some basic ideas. I have figured out how to make spirals and with that I wanted to make...

today at some class at the university we were taught about the propagation of EM (electromagnetic) waves and that they lose energy proportional to the square of distance. Then someone asked: "Why then the light propagate forever in outer space?" And the professor answered: "Light is not electroma...

I have a mobile application where I need to pre-charge the capacitors in a Victron 24v MultiPlus with a resistor before closing the circuit switch to its battery bank (24V 200Ah lithium); this prevents current inrush that would otherwise trip the battery management system on the batteries. The co...

The video below of Pythom Space's first rocket test has raised a few eyebrows The video prompted hundreds of replies on Twitter, including some from rather horrified rocket scientists. "We knew better as untrained college students," said Jordan Noone, the co-founder of Relativity Space. ...

I have three non-homogeneous trivariate polynomials in $\mathbb Z[x,y,z]$ and I want to eliminate the variables $y$ and $z$ to get a polynomial in $x$. The monomials of the polynomials are $\{1,x^4,x^2,x^2y,x^2z\}$ and I want to reduce to univariate polynomial over $\mathbb Z[x]$. Is there an aut...

Let's take the problem of the backpack: $A_1,... ,A_n$ the weights that are integers, and we want to know if we can achieve a total weight of $V$. We take $I=\dfrac{1}{2\pi}\int_0^{2\pi} \exp(-iVt)\times (1+\exp(iA_1t))\times...\times(1+\exp(iA_nt))dt$. The question then becomes what $I=0$ or $I\...

This is a new subpanel in a workshop and the electrician told me because it's new all circuits have to be AFCI and because it's an outbuilding it should be GFCI too. So, I purchased these breakers in 20 and 15 amps, 20 for outlets, and 15 for the lights. My first issue was trying to run saws off ...

I asked this question, caused by a confusion that I was able to crystallize in the comment section of ryang's answer. What is negation? One could define it like this: $P \oplus \neg P$ That is not sufficient, however. There are many things that are of opposite truth-values. Take the proposition "...

I accidentally put my unopened canned yellow fish tuna into the fridge for about a day. I took it out and put it in the pantry. Is it safe to eat?

I’m trying to send my build to the store but when I'm trying to distribute the app with Xcode, I get this error: Invalid Provisioning Profile Signature. The provisioning profile included in the bundle 'com.grafenit.velyvelo' (Payload/Runner.app) cannot be used to submit apps to the iOS App Store...

This is a crosspost from the Mathematics Stack Exchange, I thought I'd ask here as well in case anyone knows. In the STIX package there is a character called \rangledownzigzagarrow, which corresponds to U+237C ⍼ RIGHT ANGLE WITH DOWNWARDS ZIGZAG ARROW in the Miscellaneous Technical Unicode block....

I'd like to replace the faucet (and add shut off valves below) but am unfamiliar with current piping beneath. I've done basic plumbing (valve to copper pipe via compression hookup) but these pipes don't look copper. skinny pipe 3/8" the pipe from the wall is 5/8" Main question: what are these b...

I am trying to upload an archive to App Store Connect, and suddenly am getting the following error: Invalid Provisioning Profile Signature. The provisioning profile included in the bundle cannot be used to submit apps to the iOS App Store until it has a valid signature from Apple. For more infor...

Suppose $H$ is a subgroup of a group $G$ and both have the same cardinality of $\mathbb{R}$. If $K$ is a countable subgroup of $G$, is it possible that $H$ has not countable index in the subgroup generated by $K$ and $H$? Clearly $G$ must be not abelian and $HK \neq KH$.

I have recently relocated from my home country, Japan, to Europe to work here for a while in an international team, and I am experiencing a big cultural problem about interacting with Europeans. The problem is that I am often asked face-to-face by my new coworkers and friends to do favors such as:

I'm using the decorations library to put text along a path. But the text does not appear on the path, instead, it appears in the node, how should I correct it? Also, the dotted path is not symmetrical, is there a way to make it clean and look symmetrical? How do I make solid lines of equal length...

The description for Mage Hand is: A spectral, floating hand appears at a point you choose within range. The hand lasts for the duration or until you dismiss it as an action. The hand vanishes if it is ever more than 30 feet away from you or if you cast this spell again. You can use your action t...

I think the opening takes place in a lab manipulating a zygote, not sure in vitro or vivo. Krebs cycle is mentioned. A woman carrying the embryo is spirited away. The elite class of maybe immortals searches for her. At one point an underground organization of cyborgs come to her rescue. Buildings...

I'm thinking of upgrading my laptop memory from 8gb ram to 16gb but I first would like to research how Ubuntu will handle it. First: if I just insert more ram will I have to change anything in the OS or will it work/recognize it right away? Second: Will Ubuntu behave properly once I insert more r...

I'm writing a paper on graphene nanoribbons and was wondering what the best way to create a 3d graphic of the type below is. Creating the normal graphene lattice is simple but I'm not sure how i'd go about mapping it to a cylinder.

I want to know more about the difference between ぐらい and ばかり, and when either should be used. For example in the 2 sentences below. I think either of them can be used. 駅まで2時間ぐらいで着くと思います。 駅まで2時間ばかりで着くと思います。 But for the sentences below, it will have a different meaning 30分ぐらい座りました 30分ばかり座りまし...

It's a relatively unknown Bangladeshi book. It's called "Chemistry-First Paper (Class XI-XII)" by Professor Haradhan Nag According to my book, "Electrons of s and p orbitals produce more shielding than electrons of d and f orbitals. As a result, atoms of s and p-block elements experience lower ef...

I am trying to join entries of binary numbers at the lowest level of a nested list, e.g. testlist = {{{100, 100}, {101, 101}}, {{110, 110}, {111, 111}}, {{111, 100}, {111, 110}}, {{101, 111}, {110, 101}}} Using the Row function seems to work rowlist = Table[Row[testlist[[i, j]]], {i, 4}, {j...

In English (at least in North America, don't know about other English area) you see things like 10k as an abbreviation of 10000. I'm wondering if Russian does something similar, particularly regarding this ҂ symbol I came across in Unicode's Cyrillic block, or is that and its related symbols lik...

Let's assume, that a humanity arrives on a world that's super-habitable, maybe even too much habitable, as it's 1,5 atm atmosphere consists in 38,4% of oxygen and it has a surface gravity of 1,24 of Earth's. It also has higher concentration of (1,2%) carbon dioxide, (0,5%) hydrogen and has a more...

Many historical persons have full names but also a popular adjective phrase attached to them, such as Eric the Red (Erik den Røde in Danish), Gorm the Old (Gorm den Gamle in Danish), Alexander the Great etc. I am sure there is a -nym word for this, but I can't find it.

It seems like much could be learned in this way but it seems like only orbital missions have had non-human life onboard. I could actually see NASA decide not to send a mouse and certainly not a dog/cat/monkey to Mars because of bad PR. Am I wrong? Has it happened or been contemplated or is it too...

Wheel building using a SON Dynamo hub (28 12 disc), Wheelsmith DB14 spokes (stainless; J-bend), and Velocity Atlas rims (700c; 32 hole) with a two-cross lacing pattern. Disc brake, loaded touring. The spokes bow out far from the dynamo's flange. I did all of the inner spokes first, and couldn't g...

I'm on diet for more than two month. It is variant of ketogenic, but high in protein instead of fat. I cut off the carb but use a reasonable amount of healthy fats and the rest is mostly protein (mostly egg and chicken breast), and vegetables (cucumber, Lettuce, etc.). I also walk around 15000 st...

Conformal symmetry in QFT has been extremely useful for physics. However, while most of QFT is usually done in momentum space, CFTs are usually studied in position space or in terms of Mellin transformed variables (as opposed to Fourier Transformation to go to momentum space). It seems the reason...

I would like to release a specific niche database application as open source. My only concern is that any potentially beneficial changes to the project are made available to all users of the application. The one requirement I wish to place on any user of the project, is to contribute back any cha...

I'm looking for an mass-extinction level event that would cause most life on the surface of Earth to be forced back to the oceans, one that is not feasibly reversible for humanity, before societal collapse sets in--but wouldnt kill mankind off too quick to start making rudimentary colonies deep a...

I came across the tool pictured in my collection and cannot imagine its purpose. It's a long metal pick, with sharp studs running down it in a spiral. It ends in a tip that seems to be meant to make holes. It's very sturdy.

$$\ce{Na (s) + Cl_2 (g)->NaCl(s)}$$ Is collision theory applicable for the above reaction, or is collision theory applicable only for molecules? In other words, do chlorine atoms collide with sodium atoms to produce sodium chloride , or does the chlorine atom get near the sodium atom, electron tr...

Are there any keyboards where each key has touch sensitivity allowing for microtones and pitch bend with the fingers on individual keys? I think that would be a pretty cool instrument, but I only found pianos where the velocity was affected so not sure if it exists.

I found a quote online in the form of a photo from what looks like some newspaper: The photo contains an alleged quote from Henry Kissinger's speech to the WHO Council on Eugenics on February 25, 2009, and it reads: Once the herd accepts mandatory vaccinations, it's game over. They will accept ...

This is the election system in France and Ukraine. In the first round anyone can run. If no candidate wins an absolute majority, then the top two candidates go to a second round where they face off against each other. What are the relative disadvantages of this electoral system? Related: What are...

I've already posted this question in Physics Stack EXchange, but the answer that I receveid (actinide contraction similar to lanthanide contraction) is not convincing for me or at least is not detailed enough to explain the huge difference. According to Villars and Daams [Journal of Alloys and Co...

SELECT FULLTEXTSERVICEPROPERTY('IsFullTextInstalled') Above query returns 0 However, the below query returns 1 for all user databases. How to conclude whether the full text service is installed and/or used? SELECT name,is_fulltext_enabled FROM sys.databases

I don't very like the straight edge like CayleyGraph[DihedralGroup[4], VertexLabels -> Placed["Name", Center], VertexSize -> Medium, GraphLayout -> "TutteEmbedding"] I note an undocumented option "CurvedEdge", which make me happy. But I don't know why it is sometimes concave inwards and somet...

I have a problem reading my rows from the .csv database. Separated by commas every key. So, here is my .csv: id,term,description 1,"system","name" 2,"syst2","description system" 3,"syst3","no name" And here is my table where I put it (I made it MVE): \documentclass{article} %\documentclass{ICD} ...

I am trying to suppress error generated by date command but still error is coming post executing script. #!/usr/bin/bash input="30 FEB 2022" reg="^[0-9]{1,2}\s[a-zA-Z]{1,3}\s[0-9]{1,4}$" if [[ $input =~ $reg ]] then echo "VALID Date Format : $input" #output=$(`date -d "$input" +"...

DSolve[{0.0225/((1 + 0.045/f[z]^2) f[z]^4) - 1/f[z]^3 + ( 3.85274*10^6 f[z])/z^2 + (f^\[Prime]\[Prime])[z] == 0, f[0] == 1, f'[0] == 0}, {f[z]}, {z}] (*DSolve[{0.0225/((1 + 0.045/f[z]^2) f[z]^4) - 1/f[z]^3 + ( 3.85274*10^6 f[z])/z^2 + (f^\[Prime]\[Prime])[z] == 0, f[0] == 1, Derivative[1][f][0]...

I was wondering that the generalization of Pigeon hole Principle states that : If $kn+1$ pigeons are distributed in $n$ then some hole has atleast $k+1$ pigeons. This is quite obvious intuitively however, if we consider that amongst let's say $nk$ pigeons of $nk+1$ of them are considered and ...

I'm looking for a way to nullify the undesirable behaviour of some installers that append code to .bashrc to force-load their environment automatically. The problem cropped-up a few times, mostly with Conda, and in some cases the user ended-up with a broken account that prevented them from loggin...

I'm currently learning C major scale using acoustic guitar and I can play one note at a time on top of a Song. The challenge is,it doesn't sound like a music. How can I achieve good solo with it?

I was told by my teacher that a triplet will always have a three written on top. I've also seen this in theory books for graded exams which have also said that any triplet grouping will have a bracket around it. And I've read in other places that any tuplet will have a bracket over it. But I'm pl...

I would like to connect my taxon name column (value map) with a new column (scientific name). How to make a new scientific name autofilled when I choose a taxone name from the list? For example: I'm choosing name from the list in the column "taxon name": Black woodpecker, and I'd like to my secon...

Here is a pic and you can see the melody note has a rest for the last 8th note but I also added a rest for the alto and tenor, is this correct or would one rest have been ok?

Michael Ende's The Neverending Story features the Sassafranians, people who are born old and age backwards until they die as babies. F. Scott Fitzgerald's "The Curious Case of Benjamin Button" (1922) is a short story adapted to a 2008 film which tells the life story of a man who ages backwards in...

I have used a MARS model (multivariate adaptive regression splines) and I have used k fold cross validation for the evaluation of the model, obtaining the following graph: How would be the interpretation of this model? I understand that in the 6 fold, the model obtains a better AUC, but why? Wha...

Link: https://docs.microsoft.com/en-us/sql/database-engine/install-windows/change-the-database-compatibility-mode-and-use-the-query-store?view=sql-server-ver15 I am migrating sql server from 2016 to 2019. I understand that, by default, post migration the databases will retain the existing compati...

I am trying to figure out a way to have a macro where I demonstrate the output of a command then show the command via a lstinline command. I have read that I need to escape out the special char's (like { and }) and am now wondering if there is a way to do that automatically. Not sure if this is e...

I have a field called _mean and I would like to remove the decimal part of all the values of that field. I attach two pictures. One an example of my variable (_mean) in the attribute table and another the type of variable which _mean is. I am trying doing something like this Remove decimal points...

I have Nexus 92348GC-X units with 9.3.7 image version and I need to upgrade them, BUT not enoght space on this devices for new image upload (nxos 9.3.9) Moreover, I can't delete old image after I execute allow delete boot-image and try to delete due to some bug maybe. I can't delete it from bash ...

Here is my problem : i have a file with -r in the name : -r.jpg when i tried to do a : mv *.jpg old/ i have a : mv: invalid option -- 'r' even for for g in *.jpg;do echo $g &&mv "${g}" old/;done I have the same error. Regards

The minimal model program aims to find a minimal representative in the birational class of a given variety with reasonable singularities. Assuming this has been done, it seems natural to ask what these minimal models look like. Is it feasible to ask for a classification of minimal (complex) varie...

A man speaks the truth on only two days a week. The days are the same for each week and they are in the TFT form (This means that the days on which he speaks the truth are Monday and Wednesday or Friday and Sunday or Saturday and Monday, etc). On all the other 5 days, he lies. He gives the follow...

Like adding Google Analytics code, and some other things surrounding the <head> tag, how's all this done in FSE as there's no header.php? Should I use functions.php for everything?

I have problem with Zippex encoding. When I create archive with file name 'Check Flät', the name changes to strange symbols. Code that create attachment: Zippex sampleZip = new Zippex(); Blob fileData = Blob.valueOf('Sample text.'); sampleZip.addFile('layouts/Check Flät.layout', fileData, null); ...

We're about to launch our MVP and as the sole designer of the team, I know we will have some usability issues. Besides, I want to know if the product is a market fit because the main members of the team didn't conduct proper user research, only some small market research. Therefore, I want to con...

I have been using molecular fingerprints like ECFP (extended connectivity fingerprint), APFP (atom-pair fingerprint) etc. in my research to predict spectral properties of organic molecules with machine learning (basically a QSAR project). Now, I have got very good results from the machine learnin...

Macmillan Dictionary buzzword site defines text neck as: damage to the neck muscles and spine caused by frequently bending over a smartphone, tablet device, etc for long periods of time and cites an article which suggests that the expression was already in use by 2014: 'A newly coined conditio...

If there were no bitcoins at first, how did a miner approve the transaction in the genesis block? I mean if there are no mined bitcoins (balances), how can a transaction take place? Also, I know that first reward of the PoW was 50 BTC which was transferred to Satoshi, and this 50 BTC is not spend...

I'm making a procedural building with geometry nodes where the walls are instanced on a generated profile from a grid and those instanced walls are being instanced vertically along a mesh line. While the 1st instance on points node is able to randomly pick mesh from a collection that contains mor...

We see that Blessed Virgin Mary had a rather smooth travel on her way to giving birth to Jesus, bar the physical hardship of travelling to Bethlehem towards the end of her pregnancy and trying to find a place to stay. She did not have to face any temptation say, the Devil threatening her that she...

A recent answer/comment to a different question prompted me to ask this: Why does Tolkien use neither quotes nor cursive writing, and all lower-case, in this specific "quote"? Somebody seems to suggest that somebody had painstakingly scanned in all the pages, one by one, from Lord of the Rings, a...

I inserted a picture in LaTeX, but it rotated my picture. Why? \documentclass{article} \usepackage{graphicx} \begin{document} \begin{figure} \includegraphics[width=0.5\textwidth]{1.jpg} \end{figure} \end{document} All the files are here:files

In the Mass Effect trilogy, the main races (Humans, Turians, Asari, Quarians) ships use a "traditional rocket type" propulsion: Human ship (Normandy) Asari ship However, Reapers don't seem to have any propulsion: This can also be seen in the scene where the fleets attack the reapers on earth: ...

I named the species Smiles due to the constant grin they have on their faces. Their body is a perfect circle and they have 4 long limbs made of tendons and cellulose. The idea is if you cut off their limbs the cellulose would grow outward from the cut area and stem cells would grow off of the cel...

Consider the following functions: f[x_]:= {{Im[x], Re[x]}, {Re[x], Im[x]}}; g[x_]:= {{Im[x],0},{0,0}} When applying each of the functions to the list of lists {{1,2,3}}, it yields the results {{{{0, 0, 0}, {1, 2, 3}}, {{1, 2, 3}, {0, 0, 0}}}} {{{{0, 0, 0}, 0}, {0, 0}}} The problem with the se...

Assume that I have an expression like this (without evaluating) expr = 1/2/3/4/5/6/7/8/9/10 You can insert some number of parentheses into the expression above to create a valid mathematical expression. What would be the smallest possible integer value of the expression and the expression in th...

I have bought this model as is without building instructions. So I don't know if this is an original model or a fantasy car. I'm interested whether this is a original LEGO model, which one it is and if there are instructions available to rebuild it / let my son rebuild it. I suppose it is older ...

For sets $x, y$ we write $x\leq y$, if there is an injection $\iota: x \to y$, and we write $x \leq^* y$ if either $x = \emptyset$ or there is a surjection $s: y \to x$. In ${\sf (ZF)}$ we have that $x \leq y$ implies $y \leq^* y$. Consider the following statements: Partition principle (PP): For...

This is what I saw in a source I am referring to: Since both the numerator and the denominator are probabilities (so they can only take any value between 0 and 1), how can the result of division be negative?

Motivated by Federico's answer to Can a great circle be drawn between any two points on Earth? Earth is not a perfect sphere, and it can be argued that the degree of oblateness is negligible. So is the ICAO/aviation adoption of WGS-84 really necessary? Or in other words: when was the need for a t...

I can locate all of the planets other than Uranus and Neptune. This is mainly because they are very dim and I live where there is just enough light pollution so that I can't spot them. I have a Gysker 70mm telescope and a camera able to take detailed pictures of most of the planets. The only prob...

I do not currently own the Strixhaven book and one of the players in my new group is playing an Owlin (I am not DMing this one.) From the description I found online, the Owlin have hands and feet like a humanoid. Yet every picture I have seen of them shows them with bird talon feet. Is there an...

I want to put up a 4-foot wooden fence at the back of my garden, but I'm concerned that the hedge on the other side will grow over/under/through my new fence. On the other side of my garden is an open field with a hedge that is not maintained that grows into my garden. I have recentrly had it cut...

I just saw this video of Russian tanks on a video on Twitter. I can see four different flags flown by the soldiers but I can't make out what they are apart from the last one which just looks like the flag of Russia. I tried to screenshot them as best as I could but what are they and what does the...

I checked this book out of a library in the 70's, so it might be from earlier. I remember the "Enchanted Village" story by Van Vogt, and the cover image of a floating rock. I think it was "The Castle of the Pyrenees" by Magritte, or something similar. Would love to find it or its equivalent with...

I'm trying to understand Hopf Galois Theory, and I decided to try studying some example of a non commutative ring extension. The papers I've studied tell me that, for a strongly $G$-graded algebra $A$ over a fixed commutative ring $K$, the corresponding Hopf algebra $H$ (that will verify that $A$...

I have a Roth IRA and so far I've only contributed to a target fund. If I contribute $500 dollars to the IRA, could I buy whatever I want, such as $500 dollars in Apple stock? If so, when I want to withdraw funds from the IRA, will it be simple to sell the different assets and turn them into cash...

My Necromancer is a level 13 player character, and he will use the magic jar spell on fellow 13th-level PCs. The issue is that HP for PCs is calculated and based on a class feature (monsters without classes are different than PCs). The magic jar spell description says you retain the benefit of yo...

Let $R$ be a commutative ring, $M$ be an $R$-module, and $N$ be a submodule of $M$. Assume that both $M$ and $N$ are flat, so we can identify $N\otimes_RN$, $M\otimes_RN$, and $N \otimes_RN$ as submodules of $M\otimes_RM$. Is it true that $N\otimes_R N = (M\otimes_RN)\cap (N\otimes_R M)$? If not ...