qid int64 1 4.65M | metadata sequencelengths 3 3 | prompt stringlengths 31 25.8k | chosen stringlengths 17 28.2k | rejected stringlengths 19 40.5k | domain stringclasses 28
values |
|---|---|---|---|---|---|
49,709 | [
"https://mathoverflow.net/questions/49709",
"https://mathoverflow.net",
"https://mathoverflow.net/users/10909/"
] | I'm assuming someone must have scooped me on this simple argument. Where does it (first) appear in the literature?
Fix an ultrafilter $\mu$ on $\omega$, the natural numbers.
Alice and Bob play a nim-like game. At the start each player "holds" the empty set and the
the starting "position" consists of $\omega$. Beg... | Or just take all powers of $3$ and add to them all numbers that are congruent to $1$ modulo $3$.
| This is false. We construct $A$ inductively, so that the following holds:
<ul>
<li>$A$ contains all powers of two larger or equal than $4$ and no other even numbers.</li>
<li>The number of odd numbers in $A$ between $2^j$ and $2^{j+1}$ is $2^{j-2}$.</li>
<li>No power of two is in a 3-AP contained in $A$.</li>
</ul>
W... | https://mathoverflow.net |
3,045,344 | [
"https://math.stackexchange.com/questions/3045344",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/569640/"
] | I have a book about group theory and there was the following question:
<blockquote>
Let <span class="math-container">$G$</span> be a set of all the real matrices in the following form: <span class="math-container">$\begin{pmatrix}a & b\\
-b & a
\end{pmatrix}$</span> when <span class="math-container">$a^2+b^2... | The only potential problem with choosing <span class="math-container">$E$</span> so <span class="math-container">$0 < \mu(E) < \infty$</span> is that there are positive measures <span class="math-container">$\mu$</span> with sets <span class="math-container">$E$</span> such that <span class="math-container">$\mu(... | Here's one problem: Having <span class="math-container">$f\ne 0$</span> on <span class="math-container">$E$</span> doesn't imply that
<span class="math-container">$$
\int_E f\, d\mu \ne 0.
$$</span>
For instance, the positive and negative part of <span class="math-container">$f$</span> could cancel each other on <span ... | https://math.stackexchange.com |
594,479 | [
"https://physics.stackexchange.com/questions/594479",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/257503/"
] | For an Intro. Thermal Physics course i am taking this year, I had a simple problem which threw me off-guard, I would appreciate some input to see where i am lacking. The problem is as follows:
Does the entropy of the substance decrease on cooling? If so, does the <strong>total</strong>
entropy decrease in such a proces... | Simple answer yes,
Think about taking two extreme cases :
How much does a slinky extend in a gravity-free space? None at all
How much would it extend if it was on perhaps Jupiter or even a black hole ?It should extend by a large amount.
Gravity does play a role.
| If a slinky is hanging vertically in a gravitational field, the amount of stretch in any short section depends on the weight of the coil hanging below that section. Less gravity will produce less stretch.
| https://physics.stackexchange.com |
652,455 | [
"https://electronics.stackexchange.com/questions/652455",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/248767/"
] | I was thinking about diamonds, and how they're excellent thermal conductors and yet at the same time very good electrical insulators.
Does the opposite of diamond exist, i.e. are there commonly available, inert (as in, safe to use/handle) conductors with poor thermal conductivity?
| <blockquote>
<em>Does infinite magnetic permeability (e.g. for an ideal transformer)
violate conservation of energy?</em>
</blockquote>
Infinite magnetic permeability produces infinite inductance (even for a single turn coil) and, the rate of change of current that can be produced through an infinite inductance when ap... | The piece would "short out" the H field. The energy in a unit volume of a magnetic core is B times H, and -- of necessity -- the H field would be zero. So the energy stored in the core would be zero.
I'm not sure how this would work out with a solenoid core (i.e., an open core). For a toroidal core a simpl... | https://electronics.stackexchange.com |
131,470 | [
"https://security.stackexchange.com/questions/131470",
"https://security.stackexchange.com",
"https://security.stackexchange.com/users/119006/"
] | I recently had a call from whom I thought was my broadband company. As the call went on, I realised that it was someone who was trying to hack my bank details. They asked for a card reader, as they wanted to refund me. An amount of money which was not true, but cut the story short. They convinced me that I needed to lo... | I think your basically on the right track. Your client needs to provide some
token which your server will recognise or accept as proof that the client is
legitimate. How to do this depends on a number of factors and what the risks are
you are trying to protect against. There is no one single solution.
Some of the thi... | Most services do not validate the application being used as it is extremely hard to get a relatively reliable answer. Therefore what they can validate is the user through authentication and possibly their location through the IP address.
That said, some servers do validate the application, but because there is <stron... | https://security.stackexchange.com |
509,039 | [
"https://physics.stackexchange.com/questions/509039",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/134777/"
] | Coulomb's law states that if we have two charges <span class="math-container">$q_{1}$</span> and <span class="math-container">$q_{2}$</span>, then <span class="math-container">$q_{1}$</span> will act on <span class="math-container">$q_{2}$</span> with a force <span class="math-container">$$ \textbf{f}_{12}=\frac{q_{1}q... | <blockquote>
Suppose the only things we knew was that the repulsive forces vary like <span class="math-container">$r^{-2}$</span>, and that they depend on the magnitude of the charges involved. Can we infer from these two observations alone that <span class="math-container">$\textbf{f}_{21}=-\textbf{f}_{12}$</span>?... | It is worth repeating that <strong>laws</strong> in physics are <strong>axioms</strong>, there is no proof or derivation other than that the law is necessary, so that a physical mathematical theory can choose those solutions that will <strong>fit existing data</strong> and, important, will be <strong>predictive</stro... | https://physics.stackexchange.com |
736,210 | [
"https://physics.stackexchange.com/questions/736210",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/346417/"
] | My question is in regards to the variational principle in approximating the wavefunction of Helium.
<strong>Some Background:</strong>
<span class="math-container">$$\hat{H}=-\frac{\hbar^2}{2m_{e}}\nabla_{1}^{2}-\frac{\hbar^2}{2m_{e}}\nabla_{2}^{2}-\frac{Ze^2}{4\pi\epsilon_{0}r_{1}}-\frac{Ze^2}{4\pi\epsilon_{0}r_{2}}+\f... | <span class="math-container">$\newcommand{\bra}[1]{\langle #1 \rvert}$</span>
<span class="math-container">$\newcommand{\ket}[1]{\lvert #1 \rangle}$</span>
<span class="math-container">$\newcommand{\amat}[4]{\left(\begin{matrix}#1 & #2 \\ #3 & #4 \end{matrix}\right)}$</span>
<blockquote>
Why is the full Hamilto... | This is because the variational approach seeks an optimal wavefunction for a <em>fixed</em> Hamiltonian.
What is unusual about the helium atom is that the guess function is a solution to the problem <em>with interactions</em> but its form is very closely related to the form of the exact solution <em>without inteaction<... | https://physics.stackexchange.com |
1,562,294 | [
"https://math.stackexchange.com/questions/1562294",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/244966/"
] | (Quant Job interviews Questions and Answers Q3.22)
<blockquote>
Suppose we have an ant travelling on edges of a cube going from one vertex to the other. The ant never stops and it takes it one minute to go along one edge. At every vertex the ant randomly picks one of the three available edges and starts going along th... | Look at the distance from the origin after an even number $2k$ of minutes.
This distance can only be 0 or 2. In two minutes the ant can do the following :
$0 \rightarrow 1 \rightarrow 0$ with probability $1\cdot1/3$
$0 \rightarrow 1 \rightarrow 2$ with probability $1\cdot2/3$
$2 \rightarrow 1 \rightarrow 0$ with pr... | To model this as a Markov chain, let $$S=\{(0,0,0),(0,1,0),(0,0,1),(0,1,1),(1,0,0),(1,1,0),(1,0,1),(1,1,1)\}$$ and $P$ an $8\times8$ matrix with $P_{ij}=\frac13$ if $i$ and $j$ vary in exactly one digit, $0$ otherwise. Let $\{X_n:n\geqslant 0\}$ satisfy $$\mathbb P(X_{n+1}=j\mid X_0=i_1, \ldots, X_{n-1}=i_{n-1},X_n=i)... | https://math.stackexchange.com |
559,643 | [
"https://electronics.stackexchange.com/questions/559643",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/248108/"
] | As an electronics hobbyist, I've already built a thing or two so this didn't seem like a complicated thing to do, but I was terribly mistaken. I wanted to build an FM modulated radio transceiver controlled by an Arduino board that would work anywhere between 86 and 520 MHz so that it'd include normal FM radio, VHF and ... | <blockquote>
I expected there to be a miracle IC that would just require an audio and carrier wave input
</blockquote>
Ah, but FM actively modulates a carrier; you can of course use the external oscillation input as carrier for a superhet design, but then you'll still need to generate the FM-modulated IF <em>and</em> ... | Most of the answers are treating the transmit side. Basically however, the fundamental problem is that building such wideband tranceivers, fm, am or whatever is just very difficult.
I suspect that you are not going to find any transceivers that cover a continuous range up to 500 MHz. If you did, they would probably inc... | https://electronics.stackexchange.com |
9,302 | [
"https://physics.stackexchange.com/questions/9302",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/1927/"
] | I think I saw in a video that if dark matter wasn't repulsive to dark matter, it would have formed dense massive objects or even black holes which we should have detected.
So, could dark matter be repulsive to dark matter? If so, what are the reasons? Could it be like the opposite pole of gravity that attracts ordinar... | Lubos Motl's answer is exactly right. Dark matter has "ordinary" gravitational properties: it attracts other matter, and it attracts itself (i.e., each dark matter particle attracts each other one, as you'd expect).
But it's true that dark matter doesn't seem to have collapsed into very dense structures -- that is, th... | Dark matter surely has to carry a positive mass, and by the equivalence principle, all positive masses have to exert attractive gravity on other masses.
Also, from the viewpoint of phenomenological cosmology, we obviously want dark matter to attract itself. It has to attract visible matter because this is why dark mat... | https://physics.stackexchange.com |
138,582 | [
"https://cs.stackexchange.com/questions/138582",
"https://cs.stackexchange.com",
"https://cs.stackexchange.com/users/134947/"
] | I was looking to solve this reduction, but I dont see how to construct the new graph. It seems very simple but I'm not capable of do it.
I give you the complete explanation about this reduction.
We consider a variant of the independent set problem which we shall call, Independent Set with
a Fixed Node, in which the inp... | As I understand, your problem is a decision problem defined as such:
Independant set with fixed vertex (ISFV):
<ul>
<li>Input: a graph <span class="math-container">$G = (V, E)$</span>, a vertex <span class="math-container">$u \in V$</span>, an integer <span class="math-container">$k$</span>.</li>
<li>Question: is there... | Suppose that we are given a graph <span class="math-container">$G$</span> and want to know whether it has an independent set of size <span class="math-container">$k$</span> containing <span class="math-container">$u$</span>. Such an independent set cannot contain any neighbor of <span class="math-container">$u$</span>,... | https://cs.stackexchange.com |
337,385 | [
"https://math.stackexchange.com/questions/337385",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/67928/"
] | Suppose we have matrices $A, B, C$ of dimensions $m \times n, m\times n, n \times l$ respectively. How can we prove $(A+B)\circ C = A\circ C + B \circ C$ (using the summation notation method?)
| Tedious way...coefficientwise:
$$
((A+B)C)_{i,j}=\sum_{k=1}^n(A+B)_{i,k}C_{k,j}=\sum_{k=1}^n(A_{i,k}+B_{i,k})C_{k,j}
$$
$$
=\sum_{k=1}^nA_{i,k}C_{k,j}+B_{i,k}C_{k,j}=\sum_{k=1}^nA_{i,k}C_{k,j}+\sum_{k=1}^nB_{i,k}C_{k,j}
$$
$$
(AC)_{i,j}+(BC)_{i,j}=(AC+BC)_{i,j}
$$
for all $1\leq i\leq n$ and all $1\leq j\leq l$. So $(A... | <strong>Hint:</strong> Look at the linear maps represented by $A$, $B$ and $C$.
| https://math.stackexchange.com |
330,602 | [
"https://softwareengineering.stackexchange.com/questions/330602",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/82182/"
] | the QA team should ideally do their testing on an environment that almost exactly matches the prod env (to minimize uncaught bugs that arise due to setting differences).
If that's true, does the QA team typically do the testing again on prod post deployment in the googles and amazons out there? If the answer is yes t... | Depends what you're doing, but often you can't test in production because the system is now attached to real resources. In the case of Amazon, would you run a real order with a real credit card and wait for the book to arrive? You often need to be careful about putting test data into a production system.
Once it's gon... | You don't test in production because you won't find anything you don't find in a proper test environment. Maybe some kind of quick check if deployment went ok, but this is not a big part of testing.
First you test your code (unit test).
Then you test your code in the whole application (integration test).
Then you te... | https://softwareengineering.stackexchange.com |
964,509 | [
"https://math.stackexchange.com/questions/964509",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/181674/"
] | In isosceles trapezoid $ABCD$, $AB=6$, $BC=9$, $CD=8$, and $AD=9$ find the distance from point $D$ to $BC$ (perpendicular).
| Here are some questions you should be able to answer, which will help you to find the answer you're looking for.
<ol>
<li>What is the distance from $AB$ to $CD$? (<em>Hint</em>: Use Pythagorean Theorem.)</li>
<li>What is the area of triangle $BCD,$ given the answer to the first question?</li>
<li>If we consider $BC$ a... | A picture can help a lot:
$\hspace{3cm}$<img src="https://i.stack.imgur.com/00Dtl.png" alt="enter image description here">
<strong>Hint:</strong> Find a couple of similar right triangles (one of which you know a couple of sides).
| https://math.stackexchange.com |
71,509 | [
"https://physics.stackexchange.com/questions/71509",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/27232/"
] | The classic example of an indeterministic system is a radioactive isotope, e.g. the one that kills Schrödinger's cat.
I get there are arguments against hidden variables in quantum mechanics, but how could they be so sure, back in the twenties, that the strong nuclear forces involved in radioactivity were not governed ... | Schrödinger came up with the cat in 1935, which was relatively late in the development of quantum mechanics.
Back in the 1920's there had been a lot more uncertainty. The Copenhagen school had wanted to quantize the atom while leaving the electromagnetic field classical, as formalized in the Bohr-Kramers-Slater (BKS) ... | It was known that a nucleus existed back in the 20's. If you ever did experiments with nuclear decay you would see the hallmarks of a Poisson process. I am talking about simple undergraduate experiments, which, I guess, that in most countries even theoreticians specializing in other branches have to do before they get ... | https://physics.stackexchange.com |
20,410 | [
"https://dba.stackexchange.com/questions/20410",
"https://dba.stackexchange.com",
"https://dba.stackexchange.com/users/2321/"
] | I am more experienced with SQL Server and Sybase than Oracle, and understand those products well. I've been asked to look for ways to reduce the server estate running Oracle. I understand that an instance in Oracle maps to a database hosting many tablespaces. I have a fairly good grasp of the fundamentals, however if I... | You have two options:
<ol>
<li>Run multiple Oracle instances on the same machine</li>
<li>Consolidate all of your Oracle instances into a single instance,
placing the data in separate schemas</li>
</ol>
Since you're familiar with SQL Server/Sybase, I'll explain the difference between them & Oracle as far as datab... | It is fairly easy to consolidate multiple databases into one real database. In Oracle, a database is the collection of files. Users connect to the database by connecting to an instance. A database can be served by multiple instances, in which case you are running RAC.
So for simply consolidating database into one sing... | https://dba.stackexchange.com |
260,257 | [
"https://mathoverflow.net/questions/260257",
"https://mathoverflow.net",
"https://mathoverflow.net/users/100898/"
] | Let $a,q$ be a positive integers. I am trying to evaluate the following sum:
$\sum_{\substack{1<a<q \\(a,q)>1 \\ (a+1,q)>1}}1$. Is there a formula that exists to calculate such sums?
Here is an example:
Let $q=15$.
We have the following multiple of divisors:
1,2,3,5,6,9,10,12,15.
But since the two pair... | At first, we count the number of residues $a$ for which both $a$ and $a+1$ are coprime with $n$. Let $q=\prod p_i^{k_i}$ be a factorization of $q$. For any $p_i$, there exist $p_i-2$ admissible remainders modulo $p_i$ (forgotten remainders are 0 and $-1$), thus $(p_i-2)p_i^{k_i-1}$ admissible remainders modulo $p_i^{k_... | What you have written down is already a formula for calculating the sum, so really you need to be more precise about what the question is.
But here are some comments which give a simpler formula in the case where $q$ is only divisible by a few primes.
If $q$ is a prime power $p^e$, then the sum is zero, because $(a,q... | https://mathoverflow.net |
59,062 | [
"https://dba.stackexchange.com/questions/59062",
"https://dba.stackexchange.com",
"https://dba.stackexchange.com/users/9353/"
] | I have a table (not designed by me) which has 20 variably named columns. That is, depending on what type of record you are looking at, the applicable name of the column can change.
The possible column names are stored in another table, that I can query very easily.
Therefore, the query I'm really looking for goes so... | Try the following code:
<pre><code>CREATE TABLE #Names
(
[Type] VARCHAR(50),
ColNum SMALLINT,
ColName VARCHAR(50),
ColDataType VARCHAR(20)
)
INSERT INTO #Names VALUES
('Customer', 1, 'CustomerID', 'INT'),
('Customer', 2, 'CustomerName', 'VARCHAR(50)'),
('Customer', 3, 'CustomerJoinDate', 'DATE'),
('C... | This sounds prime for a front end display solution. Query 1 would pull back your data, Query 2 would pull back the column names and in code when you build what ever structure you use to display you set the headers from the second query.
While a Pure SQL Method may be possible it will be dynamic SQL and code maintnenc... | https://dba.stackexchange.com |
151,163 | [
"https://stats.stackexchange.com/questions/151163",
"https://stats.stackexchange.com",
"https://stats.stackexchange.com/users/-1/"
] | <blockquote>
Implement an estimator using Monte Carlo integration of the quantity
$$\theta=\int_0^1e^{-x^2}(1-x)dx$$ Estimate $\theta$ with a variance
lower than $10^{-4}$ by writing the variance of this estimator depending on
sample size.
</blockquote>
We can write
$$\theta=\int \phi(x)f(x)dx$$
where $\phi(x... | The problem is that without knowing exactly what <span class="math-container">$\theta$</span> is, we cannot know the variance of its Monte-Carlo estimator. The solution is to <em>estimate</em> that variance and hope the estimate is sufficiently close to the truth.
<hr />
<strong>The very simplest form of Monte-Carlo e... | <blockquote>
Implement an estimator using Monte Carlo integration of
$$\theta=\int\limits_0^1e^{-x^2}(1-x)dx$$
</blockquote>
While you can use a $\mathcal{U}([0,1])$ distribution for your Monte Carlo experiment, the fact that both $$x \longrightarrow \exp\{-x^2\}\quad \text{and}\quad x \longrightarrow (1-x)$$ are ... | https://stats.stackexchange.com |
47,476 | [
"https://softwareengineering.stackexchange.com/questions/47476",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/14/"
] | In academia, it's considered cheating if a student copies code/work from someone/somewhere else without giving credit, and tries to pass it off as his/her own.
Should companies make it a requirement for developers to properly credit all <em>non-trivial</em> code and work that they did not produce themselves? Is it use... | I'd say this is probably essential. For one thing, the company may need to deal with any license terms and other legal implications - just because it's "free" doesn't mean you can do what you like with it.
However, there may be an exception with example code copied and adapted from reference books. After all, that's b... | I always do. I also link back to the original source. I do this more for reference then to give credit. (So I can go back and see the original authors notes and or updates)
I think its good practice, but totally unenforceable, having a policy in place is almost worthless, as I don't think it will change anyones behavi... | https://softwareengineering.stackexchange.com |
20,922 | [
"https://electronics.stackexchange.com/questions/20922",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/5651/"
] | I'm currently working on a project involving (I think 3mm, 1.5VDC) Infrared LEDs. However, due to my photoresistor, I think the current, voltage, or whatever (forgot) will vary greatly to minuscule amounts. So, do these LEDs need UVLOs? They are very, very sensitive and I've already wasted half the pack.
| No.
LEDs are not damaged by low voltages.
If you are damaging LEDs, you must be driving them beyond their rated currents. Show your circuit to receive advice.
In general, very few electronic components are damaged by undervoltage. Some microprocessors can mis-execute in a brownout condition, which could have undes... | LEDs cannot be damaged by "forward" voltages that are so low that they do not draw rated current.
They <strong>can</strong> be damaged by voltages that are low by normal standards.<br>
An infrared LED may easily be destroyed by a 3V3 or 5V power supply if current in excess of its maximum rated current flows.
LEDs ... | https://electronics.stackexchange.com |
336,231 | [
"https://physics.stackexchange.com/questions/336231",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/120802/"
] | If you (hypothetically) had an infinitely cold ice cube (an ice cube that stays at absolute zero no matter how much heat it absorbs), how long would it take for the Universe to cool down to absolute zero?
| There is no such thing as a infinity cold ice cube.
The closest scenario I can think of is a system with a heat sink; a system coupled to a very large heat reservoir. You can them solve a heat equation.
You should also take into account that only at
$$t\rightarrow \infty $$
will the temperature of the system equal ... | Absolute zero means that the particles aren't moving at all. Any thermal energy will be absorbed by the cube. If we assume diffusion as the only method of heat transfer, there must be a direct chain of mass from the cube to all other objects in the universe for it to absorb energy from all of them. The second there is ... | https://physics.stackexchange.com |
413,788 | [
"https://electronics.stackexchange.com/questions/413788",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/194133/"
] | I am having a difficultly with producing <span class="math-container">\$S, P, Q \$</span> and <span class="math-container">\$D\$</span> from Instantaneous Power <span class="math-container">\$p(t)\$</span>.
Let's say that both voltage and current are clear sine waves. Then:
<span class="math-container">\$p(t) = Vsin... | I think I found the answer I am looking for. I am presenting it here, so it will be available to anyone that is interested.
First consider:
<span class="math-container">\$v(t) = V_1cos(ω_1t+φ_{V_1}) \\ i(t)=I_1cos(ω_1t+φ_{I_1})\$</span>
then:
<span class="math-container">\$p(t) = v(t)\cdot i(t) = \\V_1I_1cos(ω_1t+φ... | Starting with the <strong>definition</strong> for active power
<span class="math-container">\$P = \frac{1}{T} \int_0^T v(t) \cdot i(t) \cdot dt = \frac{1}{T} \int_0^T p(t) \cdot dt\$</span>
one gets the following expression for the power for linear networks (containing R, L, C, all constant):
<span class="math-cont... | https://electronics.stackexchange.com |
395,028 | [
"https://physics.stackexchange.com/questions/395028",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/185504/"
] | I´ve searched about this but I cant really find an answer that satisfies me.
What happens that determines " This wave has frequency value equal to x Hz and a value of wavelength equal to y "
I cant seem to understand this... Does the wavelength has anything to do with length is there something moving up and down and... | <blockquote>
Does the wavelength has anything to do with length is there something moving up and down and each cycle is a complete wave
</blockquote>
In classical EM, the answer is that the wavelength is the distance between the peak voltages in the electric field.
When you think of a water wave, it's easy to see t... | My understanding is that what is moving up and down is the strength of the electric field at a particular point in space. EM radiation is generated by the mechanical vibration of charged particles. Remember a charged particle casts an electric field that decays as 1/r^2. When a charged particle moves, say in the +x d... | https://physics.stackexchange.com |
8,423 | [
"https://cardano.stackexchange.com/questions/8423",
"https://cardano.stackexchange.com",
"https://cardano.stackexchange.com/users/5844/"
] | I have a Daedalus wallet running which is a full node so in theory, I should get all the CLI functionality from that one install, how do I access it?
| Daedalus has its own <code>cardano-node</code> instance, so you can specify the node's socket variable and use it for <code>cardano-cli</code> purposes.
First, launch Daedalus, and click on Help > Daedalus Diagnostics. Under the "Core Info" section, the "Daedalus State Directory" specifies the fi... | Go to the Deadalus menu, and you should see a menu item that says "Open a Marlowe terminal", and a terminal will open with Marlowe Cli installed.
| https://cardano.stackexchange.com |
139,677 | [
"https://mathoverflow.net/questions/139677",
"https://mathoverflow.net",
"https://mathoverflow.net/users/8133/"
] | DISCLAIMER: All pointclasses considered here are boldface.
Most of the time, when doing descriptive set theory, we want the projective sets to "behave well;" for example, maybe we don't want there to be nonmeasurable projective sets, or projective well orderings of $\mathbb{R}$, etc. Generally, this means making some ... | Unless I am mistaken, it seems to me that $\Delta^1_2$ does have the uniformization property in $L$.
For any set $A$ in $\Delta^1_2$, let $B$ select the $L$-least witness on each slice. So $B$ unifomizes $A$, and the graph of $B$ appears to be $\Delta^1_2$, by the following reasoning:
<ul>
<li>$x\oplus z\in B$ if an... | Assuming $V=L$ then we have $AC$ and $CH$, so every set of reals is at most $\aleph_1$ Suslin. So we can find scales for them and uniformize them.In particular every $\Delta^1_2$ set of reals can be uniformized. As Joel said in the comment above this works for all $\Delta^1_n$ under $V=L$.
| https://mathoverflow.net |
45,449 | [
"https://mathoverflow.net/questions/45449",
"https://mathoverflow.net",
"https://mathoverflow.net/users/756/"
] | <strong>SymMonCat</strong> is the cartesian 2-category of symmetric monoidal categories, braided monoidal functors, and monoidal natural transformations. The terminal symmetric monoidal category <strong>1</strong> has one object $I$ and $I \otimes I = I$.
A category enriched over a monoidal category $V$ assigns to ea... | [Ignore this first part, I'm just leaving it for the context to the comments below.]
It is hard for me to understand why you would want to enrich in symmetric monoidal categories, have an identity, and also want this identity to <em>not</em> be the unit of the symmetric monoidal category.
That said, you can always ... | I suppose that the monoidal structure for $ SymMonCat$ you mean is the cartesian one, and as braided functor you mean a pseudo-monidal symmetrical (funtors that commutes with the canonical isomorphism of symmetry, and the coherence morphism data are isomorphisms). Then $\mathcal{C}(X, X)\in SymMonCat$ has a internal... | https://mathoverflow.net |
74,800 | [
"https://cs.stackexchange.com/questions/74800",
"https://cs.stackexchange.com",
"https://cs.stackexchange.com/users/55524/"
] | We define $\mathbf P$ as the set of problems solvable in polynomial time. We define $\mathbf{NP}$ as the set of problems with a verifier $ \in \mathbf P$.
Is there a name for problems whose verifiers are $\in \mathbf {NP}$ (e.g., $\mathbf{N(NP)}$)? I can't see this being a very <em>useful</em> complexity class, but, f... | Suppose you had a problem such that for any $x \in L$, there was a verifier $v$ such that $v$ could be checked against $x$ by a nondeterministic polynomial time algorithm. For a valid $(x, v)$ pair, there is some verifier $v'$ such that it takes polynomial time to check $((x, v), v')$ is a correct verification.
But th... | If a problem has a verifier you can guess it with nondeterministic TM so it is automatically in NP.
| https://cs.stackexchange.com |
28,061 | [
"https://quant.stackexchange.com/questions/28061",
"https://quant.stackexchange.com",
"https://quant.stackexchange.com/users/5641/"
] | I'm self studying for an actuarial exam and I am curious about a property of the antithetic variate method for increasing the Monte Carlo price accuracy (i.e. For every random draw of $z$, also include a draw of $-z$ in the simulation).
<strong>Question:</strong>
Assume the Black-Scholes framework and consider a Euro... | No, you can have
$$
\frac{1}{2n}\sum_{i=1}^{2n} C(S^i_T,K,T) = 0
$$
First off, there's the obvious case where $n=1$ and $u_1 = 0.5$
More generally, for options way out of the money it is common to have
$$
\frac{1}{n}\sum_{i=1}^{n} C(S^i_T,K,T) = 0
$$
even for very large $n$. Antithetic sampling does not change... | No. Antithetic variable method is usually for generating smaller standard error than your non-antithetic method, which is a direct result of the negative correlation between original variable and the antithetic variable.
For OTM option, there definitely will be a lot of path ending up with value 0. What may be a choic... | https://quant.stackexchange.com |
1,118,226 | [
"https://math.stackexchange.com/questions/1118226",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/203535/"
] | I read that for $y=ax^2+bx+c$ is a quadratic function where $a\neq0$, but is it true that $a$ really can't be zero? I think it is because if $a$ <strong>was</strong> zero, there wouldn't be a parabola. There would just be a flat line, so then it wouldn't be quadratic because the $x^2$-term indicates if the parabola o... | If $a=0$, you no longer have a parabola.
Instead, you have a line: $y = bx+c$, with slope equal to $b$, and a $y$-intercept at $c$.
| I guess I'm right. If $a$ is zero, then $y=ax^2+bx+c$ would change to $y=bx+c$, leaving $b$ as the slope and $c$ as the y-intercept, leaving a flat line, not a parabola.
| https://math.stackexchange.com |
316,555 | [
"https://softwareengineering.stackexchange.com/questions/316555",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/113314/"
] | In C++ I frequently see these two signatures used seemingly interchangeably:
<pre><code>void fill_array(Array<Type>* array_to_fill);
Array<Type>* filled_array();
</code></pre>
I imagine there is a subtle difference, but I don't know what it is.
Could someone explain when I might prefer one form over the o... | The first kind of signature is usually preferable.
The difference is that the second signature requires the array to be created inside the function. In particular, the second signature effectively requires the array to <strong>outlive the scope in which it was created</strong>. So what we're really comparing are these... | It seems most likely that the second one returns <code>Array<Type></code> and not <code>Array<Type>*</code>. In the first case, there is an <code>Array<Type></code> somewhere and you pass a pointer to it, so the function can fill it. In the second case, the function creates an object and returns it (u... | https://softwareengineering.stackexchange.com |
156,874 | [
"https://dba.stackexchange.com/questions/156874",
"https://dba.stackexchange.com",
"https://dba.stackexchange.com/users/111846/"
] | My question is regarding database design/architecture, but I'll use a familiar example to explain it.
Suppose there is a database for banking. This database has a table called <code>Customers</code> which stores <code>ID</code>, <code>Name</code>, <code>Address</code>, etc.. Now each of these customers can have their ... | The following should help with the execution time:
<ul>
<li>remove the <code>ORDER BY</code> if it isn't strictly necessary</li>
<li>replace the join of <code>dr</code> table with <code>WHERE EXISTS (SELECT 1 FROM tms_door_record_raw As dr WHERE c.card_no = dr.card_no AND dr.record_time BETWEEN '2016-11-01' AND '2016-... | Remove the GROUP BY.<br>
If you have (logicaly valid) duplicates remove them at early stage.
| https://dba.stackexchange.com |
169,485 | [
"https://electronics.stackexchange.com/questions/169485",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/32541/"
] | I'm reading the first chapter of the AoE. I've come across this section on differentiator/integrator circuits and couldn't understand the math behind it.
<img src="https://i.stack.imgur.com/pNe7M.png" alt="differntiator">
<img src="https://i.stack.imgur.com/2cM4z.png" alt="integrator">
For the first picture, it says... | What they mean is that a passive R/C filter can only approximate a differentiator/integrator so long as the time constant is much slower than the signal. The reason for this is that the true behavior of an R/C and R/L circuit is exponential in time e.g. from basic circuit theory, the general response of an RC circuit i... | As an alternative, you can watch the phase response of the circuits.
Remember that an ideal differentiating (integrating) process requires a phase shift between input and output of +90deg (-90deg). A passive C-R resp. R-C combination allows these values for infinite frequencies only. Hence, only an approximation of the... | https://electronics.stackexchange.com |
178,582 | [
"https://physics.stackexchange.com/questions/178582",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/27123/"
] | I've previously learned that massive particles cannot achieve the speed of light.
But recently I read that, concerning the gels that refract and bounce light within around enough that it can travel at worldly speeds, and by extension how electromagnetism propagates through matter, that pure photons are thought of as i... | First, we will look at the energy of a free relativistic particle of (rest) mass $m$ moving with velocity $v$:
$$E = \frac{mc^2}{\sqrt{1-\frac{v^2}{c^2}}}$$
where $E=mc^2$ when $v=0$. We now consider a few cases:
<ol>
<li>$m\ne0$:
In this case, $E\rightarrow\infty$ as $v\rightarrow c$. Therefore, a massive particle th... | Every particle needs to have energy to be a particle (if it had none it wouldn't even exist). Since energy is equivalent to mass and therefore gravitates I would say YES, all particles that have a speed less than the speed of light must also have mass.
Because the speed of the particle is less than the speed of light ... | https://physics.stackexchange.com |
335,218 | [
"https://softwareengineering.stackexchange.com/questions/335218",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/157012/"
] | From Wikipedia on Single responsibility principle SoC
<blockquote>
... class should have responsibility over a single part of the functionality provided by the software, and that responsibility should be entirely encapsulated by the class. All its services should be narrowly aligned with that responsibility
cla... | <h2>General</h2>
Single Responsibility has something to say about semantic redundancy and false semantic cohesion of code fragments (modules, classes, methods functions). The problem is (with all SOLID principles) <strong>it's not about applying them, it's about identifying a violation them</strong>. Once you think it... | The responsibility here is <code>dog</code>. Dog is as dog does.
Many people read the Single Responsibility Principle as <em>"Must do only one thing."</em> That's not what it means. Bob Martin, author of the principle (and prolific source of mass confusion for inexperienced programmers everywhere) says it like th... | https://softwareengineering.stackexchange.com |
62,265 | [
"https://mathoverflow.net/questions/62265",
"https://mathoverflow.net",
"https://mathoverflow.net/users/2284/"
] | This semester, I teach an introduction to probability course tailored for students with no science background and so with very <em>very</em> little prerequisites. We started with the basics of analytic combinatorics then moved on to random variables and the study of common laws (binomial, hypergeometric, geometric, Poi... | What about the characterization of Poisson point processes ?
Let us consider a counting process $(N(t))_{t \ge 0}$. That is, $N(0)=0$, $N(t)$ only increases by jump of height $1$, and is right continuous. You can see $N(t)$ as the number of points of a random set in $]0,t]$.
Then $N(t)_t$ is a homogeneous poisson poi... | We can't expect a completely finite way for the Poisson distribution to arise, since the number $e$ must come from somewhere. On the other hand, it should definitely not be necessary to introduce Stirling's formula.
I think the most natural approach is to define Poisson($\lambda$) as the limit distribution of the numb... | https://mathoverflow.net |
28,118 | [
"https://physics.stackexchange.com/questions/28118",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/9129/"
] | The theory I've recently come to postulates that:
<ol>
<li>The volume of space filling the universe is finite and is constantly growing, thus the boundaries of the universe are constantly expanding.</li>
<li>The expansion of the universe's boundaries is caused by light that is converted into fresh space while reaching... | What you are describing looks like a hypothesis to me. A hypothesis is an idea. You have an idea. A theory, in the sense it is used by modern physics, is an idea about how the universe works which is supported by some rigorous elements, whether we're talking about some mathematical explorations (such as in the case of ... | The current theory for describing the large scale structure of the universe is General Relativity and in particular the FLRW metric. GR gives us a set of equations into which we can feed experimental data and from which get predictions. So far the predictions have agreed with every experiment we've done, and that's why... | https://physics.stackexchange.com |
148,799 | [
"https://softwareengineering.stackexchange.com/questions/148799",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/2673/"
] | <strong>When we say 'documentation' for a software product, what does that include and what shouldn't that include?</strong>
For example, a recent question asked if comments are considered documentation?
But there are many other areas that this is a valid question for as well, some more obvious than others:
<ul>
<li... | The goal of documentation is to describe and explain the software product, so you could define the documentation to be the set of artefacts that contribute to that description or explanation. You'd probably not consider related <em>actions</em> as part of the documentation: e.g. a week-long training course is not docum... | I think you took away the wrong part from your conversation at a conference. Modern software development methodologies advocate that the development team should be working closely with its customers (or a product owner who's acting as a customer proxy). For all work delivered, definition of "done" is something that is ... | https://softwareengineering.stackexchange.com |
477,858 | [
"https://physics.stackexchange.com/questions/477858",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/195488/"
] | Can someone in simple terms why you would use Nyquist frequency limits when processing a signal? What benefit does it provide, and how does it affect the results? And how does it relate to the Nyquist rate?
| The Nyquist sampling theorem (sometimes called the Nyquist-Shannon sampling theorem) says, if you have a signal that is bandlimited with bandwidth <span class="math-container">$B$</span>, then if you sample it with a sampling period <span class="math-container">$T_s$</span> <em>strictly</em> less than <span class="math... | As suggested by a comment, you should give us some context. There a several ways to answer the question. I'll provide a partial answer that is particularly relevant to physics, esp discrete periodic systems such as atoms in a solid. But there are other aspects, especially as concerns continuous systems and time-doma... | https://physics.stackexchange.com |
705,179 | [
"https://physics.stackexchange.com/questions/705179",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/123113/"
] | My understanding of the flatness problem is that it says that if we leave out dark energy and inflation, then the density parameter <span class="math-container">$\Omega(t)$</span> tends to <span class="math-container">$\infty$</span> or <span class="math-container">$0$</span> unless we have <span class="math-container"... | Relation between curvature <span class="math-container">$k$</span> and density parameter <span class="math-container">$\Omega$</span> can be described with 1st Friedmann equation.
<span class="math-container">$$(\frac{\dot{a}}{a})^2 +\frac{kc^2}{a^2} = \frac{ 8\pi G }{3}\rho$$</span>
Define Hubble parameter be <span cl... | As you pointed out, as we go back in time, <span class="math-container">$\Omega_{\rm total}-1$</span> needs to be very small (i.e., <span class="math-container">$|\Omega_{\rm total}-1| \propto 10^{-61}$</span>)
This situation brings to mind the following question;
Why should the universe have started from such a unique... | https://physics.stackexchange.com |
205,712 | [
"https://math.stackexchange.com/questions/205712",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/43306/"
] | I have a set of N random integers between A and B.
Assuming that my random number generator is equally likely to return any integer between A and B, how can I calculate the probability that the next random integer is already present in my set?
I want to estimate how many random numbers I should generate in a batch su... | To complete your argument you have to show that $\ln(p_n)/\ln(n) = 1.$
Now, <em>if</em> you have that $p_n \sim n\ln (n),$ then $\ln(p_n) = \ln(n) + \ln\ln(n) + o(1)$, and so indeed $\ln(p_n)/\ln(n) \to 1$ as $n \to \infty$. So at least
this is consistent with what you are trying to prove.
On the other other hand,... | There is a problem with this approach. You took $x = p_n$, but that means $\ln(x) = \ln(p_n)$ and <i>not</i> $\ln(n)$.
| https://math.stackexchange.com |
936,611 | [
"https://math.stackexchange.com/questions/936611",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/58742/"
] | let $p,q$ is postive integer,and such
$$\dfrac{95}{36}>\dfrac{p}{q}>\dfrac{96}{37}$$
Find the minimum of the $q$
maybe can use
$$95q>36p$$
and $$37p>96q$$
and then find this minimum of the value?
before I find a
$$2.638\approx \dfrac{95}{36}>\dfrac{49}{18}\approx 2.722>\dfrac{96}{37}\approx 2.59 ... | An interesting trick so solve such kind of problems is to consider the continued fraction of the LHS and the RHS. We have:
$$\frac{95}{36}=[2;1,1,1,3,3],\qquad \frac{96}{37}=[2;1,1,2,7]$$
hence
$$\frac{13}{5}=[2;1,1,2]$$
just lies between the LHS and the RHS, and it is the rational number with the smallest denominator ... | We have
$$2.64\gt a=\frac{17575}{5\cdot 36\cdot 37}=\frac{95}{36}\gt \color{red}{\frac{13}{5}}=2.6=\frac{17316}{5\cdot 36\cdot 37}\gt\frac{96}{37}=\frac{17280}{5\cdot 36\cdot 37}=b\gt 2.59.$$
Note that
$$\frac{11}{4}\gt a\gt b\gt\frac{10}{4}$$
$$\frac{8}{3}\gt a\gt b\gt\frac{7}{3}$$
$$\frac{6}{2}\gt a\gt b\gt\frac{5... | https://math.stackexchange.com |
181,694 | [
"https://mathoverflow.net/questions/181694",
"https://mathoverflow.net",
"https://mathoverflow.net/users/38889/"
] | What is known about finite groups $G$ for which there exists a Galois extension $K$ of $\mathbb{Q}$ ramified only at $2$ such that $\text{Gal}(K/\mathbb{Q}) \cong G$ ? More generally, which groups can be realized over $\mathbb{Q}$ with no ramification outside a given (finite) set of primes?
I am thus interested in res... | Let me first note that there is a slight ambiguity when one says "ramified only at 2". Strictly speaking, that means that the extension is unramified at every place
of $\mathbb Q$ except 2, including infinity. The latter mean that the extension is totally real. Often, however, "ramified only at 2" means "ramified only ... | Concerning the question of Pablo that follows Joël's answer:
If $k$ is an algebraically closed field, then the situation is completely understood, thanks to work of Grothendieck (in characteristic 0) completed by the proof of Abhyankar's conjecture by Raynaud and Harbater.
Precisely, let $C/k$ be a smooth affine cur... | https://mathoverflow.net |
5,690 | [
"https://chemistry.stackexchange.com/questions/5690",
"https://chemistry.stackexchange.com",
"https://chemistry.stackexchange.com/users/2018/"
] | In nucleophilic aromatic substitution reactions, why do fluorides react faster than bromides?
Ordinarily bromide is a better leaving group than fluoride, e.g. in <span class="math-container">$\mathrm{S_N2}$</span> reactions, so why isn't this the case here? The only thing I can think of is that fluorine is more electr... | The key point to understanding why fluorides are so reactive in the nucleophilic aromatic substitution (I will call it S<sub>N</sub>Ar in the following) is knowing the rate determining step of the reaction mechanism. The mechanism is as shown in the following picture (Nu = Nucleophile, X = leaving group):
<img src="ht... | Fluorine is the most electronegative element, and the fluoride anion is also much smaller and less polarizable than any of the other halogen anions, making its activity much more dependent on solvent effects. In protic solvents, fluoride tends to be very strongly solvated as a hydrogen bond acceptor and is thereby stab... | https://chemistry.stackexchange.com |
350,636 | [
"https://physics.stackexchange.com/questions/350636",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/30522/"
] | Is there somewhere on the internet I can find cosmological redshift data. In particular, I would like to know the redshift around the time when the acceleration of the Universe began to accelerate.
| One of the main places where data about galaxies gets aggregated is the <A HREF="https://ned.ipac.caltech.edu/" rel="nofollow noreferrer">NASA Extragalactic Database</A> (NED). For example, <A HREF="https://ned.ipac.caltech.edu/cgi-bin/objsearch?objname=M101&extend=no&hconst=73&omegam=0.27&omegav=0.73&a... | Redshift of the time when the universe started to accelerate:
From Friedmann's equations:
$$\dot{a}=aH=H_0\sqrt{\Omega_{m0}/a+a^2\Omega_{\Lambda 0}}$$
required is:
$\ddot{a}>0$.
Calculation gets you
$$a=\left(\frac{\Omega_{m0}}{2\Omega_{\Lambda 0}}\right)^{1/3} \approx 0.6$$
$\rightarrow z=1/a-1 = 0.67$
| https://physics.stackexchange.com |
1,351,142 | [
"https://math.stackexchange.com/questions/1351142",
"https://math.stackexchange.com",
"https://math.stackexchange.com/users/247415/"
] | Find a,b,c $\in \mathbb{R}$ for which the function is a) continuous, b) differentiable.
$$f(x)=\left\{\begin{array}{cc}
ax^2+bx+c & x<0 \\
2\sin x+cos x & x\:\ge 0
\end{array}\right.$$
From what I know a function is continuous when the following occurs:
$$\lim_{x\to 0^+\:}f(x) = \lim_{x\to 0^-\:}f(x) = f(... | You can use the rational root theorem to guess some roots.
<blockquote>
<strong>Rational root theorem.</strong> All rational roots have the form <span class="math-container">$\frac{p}{q}$</span>,with <span class="math-container">$p$</span> a divisior of the constant term and <span class="math-container">$q$</span> a di... | You could work by locating the roots approximately by computing at some easy values and noting sign changes - Sturm's Theorem is a heavy duty resource, and Descartes Rule of Signs can be indicative. There are more basic observations too, which can help to narrow the search amongst rational roots - using changes in the ... | https://math.stackexchange.com |
404,543 | [
"https://softwareengineering.stackexchange.com/questions/404543",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/356397/"
] | I have a code that is something like this in a class
<pre><code>string method x (){
foreach(a in alist){
//do something
}
return string;
}
integer method y (){
foreach(a in alist){
//do something
}
return integer;
}
double method z (){
foreach(a in alist){
//do something
}
return doubl... | <h2>It's not inherently a code smell</h2>
There is nothing wrong with having a <code>foreach</code> in multiple methods, <em>unless</em> you always run these three methods consecutively, at which point you can simplify it to:
<pre><code>public void xyz()
{
foreach(a in alist)
{
x(a);
y(a);
... | It's not a code smell. In fact Martin Fowler over at <code>[refactoring.com][1]</code> argues you should repeat a loop if it adds value because of the trivial computing cost of repeating said loop.
You should make alist a function argument and make the function static (if possible in the real world)
| https://softwareengineering.stackexchange.com |
39,257 | [
"https://biology.stackexchange.com/questions/39257",
"https://biology.stackexchange.com",
"https://biology.stackexchange.com/users/19159/"
] | I am learning about frameshift mutations. Frameshifts can occur due to a nucleotide deletion. Suppose that due to a frameshift, because of a deletion somewhere upstream from the original start codon, two additional start codons are generated, just before the stop codon in the new reading frame. What would happen in ter... | There is a basic misconception in the question you have asked, which @biogirl has explained. <strong>There is only one start Codon in any mRNA</strong> and it defines the <strong>open reading frame.</strong>
All other AUGs in the open reading frame are simply codons that encode for the Amino Acid Methionine and have ... | AUG functions as a start codon only when it is at the 1st position of the open reading frame. Whenever AUG is present in between, it codes for methionine amino acid. Go through the basics of translation from a good book.
| https://biology.stackexchange.com |
431,317 | [
"https://electronics.stackexchange.com/questions/431317",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/217779/"
] | I'm trying to understand the circuitry of TV signal splitters and associated boosters/amplifiers, and I have two questions.
My situation is as follows. I have a TV aerial (antenna) in my loft. It connects to a non-powered box, which I assume must be a passive splitter. From there cables run to sockets in a total of ... | You've made some wrong assumptions about what the parts of the system are. The part you're describing as a non-powered passive splitter is actually a powered active splitter. Splitting one aerial signal into six with a passive splitter is unlikely to give you sufficient signal on any of the six outputs, especially if t... | It is desirable to have the amplifier be as close to the aerial as possible and certainly prior to the signal being split, however getting mains power to said locations is often problematic.
The solution to this is amplifiers that are powered via one of the output coax lines. The amplifier is sited close to the aerial... | https://electronics.stackexchange.com |
26,154 | [
"https://ai.stackexchange.com/questions/26154",
"https://ai.stackexchange.com",
"https://ai.stackexchange.com/users/44278/"
] | I'm trying to implement Deep Q-Learning for a pet problem having a continuous state space and discretized action space.
The algorithm for table-based Q-Learning updates a single entry of the Q table - i.e. a single <span class="math-container">$Q(s, a)$</span>. However, a neural network outputs an entire row of the tab... | As you say, the output of a <span class="math-container">$Q$</span> network is typically a value for all actions of the given state. Let us call this output <span class="math-container">$\mathbf{x} \in \mathbb{R}^{|\mathcal{A}|}$</span>. To train your network using the squared bellman error you need first calculate the... | There are a couple ways you can define the architecture of a DQN. The most common way of doing it is by taking in the states and outputting the value function of all possible actions - this leads to a DQN with multiple outputs. The other, less efficient way, includes taking in an state-action as input and outputting a ... | https://ai.stackexchange.com |
511,960 | [
"https://electronics.stackexchange.com/questions/511960",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/258342/"
] | In general, if we are working on a sequential circuit, say a Flip Flop (e.g. D Flip Flop)
The code we write for the always block part is:
<pre><code> always @(posedge clk or posedge reset)
begin
if (reset) begin
// Asynchronous reset when reset goes high
q <= 1'b0;
end else begin
// Assig... | You have a valid point. If we were being very careful we would want to know if the <code>clock</code> or <code>reset</code> was actually in the <code>X</code> state, and we would probably set <code>Q</code> to <code>X</code> if that was the case.
So why don't we do those checks? The <code>clock</code> and <code>reset</... | It's implied that if the block triggered, and reset is <strong>not</strong> high, that clock rising edge must have triggered the always block (because the always block triggered either because posedge reset <strong>or</strong> posedge clk). Basically if reset is high, you want to behave like a reset no matter what in t... | https://electronics.stackexchange.com |
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