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Activity for Peter Taylor‭

Type On... Excerpt Status Date
Comment Post #282600 What makes you think that "*these authors and publishers are desperate for income*" as opposed to unsatisfied with the alternatives?
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over 2 years ago
Edit Post #283122 Initial revision over 2 years ago
Answer A: Intuitively, why would organisms — that after one minute, will either die, split into two, or stay the same, with equal probability — all die ultimately?
This can be recast as a random walk on a line. Let $nt$ be the number of amoebae after $t$ events, and process the events in any order which makes sense. (It may help to think of this as serialising a parallel process on a single-core CPU). For example, you could choose to number the the amoebae by t...
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over 2 years ago
Edit Post #283121 Initial revision over 2 years ago
Answer A: Why would skyrocketing the numbers of doors help laypeople intuit the Monty Hall Problem?
The only thing special about the door you chose is that you chose it, and you did so without any information, so objectively it isn't special at all. The door which the host leaves closed is special because it was chosen from the remaining doors by someone with information, so objectively it is actua...
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over 2 years ago
Edit Post #279044 Post edited:
A proposed edit tried to improve the typography with nbsp; this is a better fix
over 2 years ago
Comment Post #283086 Firstly, I don't see anything in the T&C on the physicsforums site which says that content is CC0-compatible, which is why I've deleted your self-answer. But secondly, even if it were, it's almost always better to write an answer in your own words once you've understood the solution to a more than su...
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over 2 years ago
Comment Post #282645 This question at present is completely different to the question originally posted and to which my previous comment applies. Recycling a question ID like that is a source of confusion. What's going on?
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over 2 years ago
Comment Post #283086 That sounds very broken. DuckDuckGo in an incognito browser window gives me a useful result from Wolfram MathWorld as the very first result.
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over 2 years ago
Comment Post #283086 What does your favourite search engine say?
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over 2 years ago
Comment Post #282658 @#8046 , go ahead.
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almost 3 years ago
Comment Post #282658 I won't pretend to be enthusiastic about the idea, but I recognise that in small communities it's sometimes necessary to serve a term in office as a public duty. I have no prior experience as a moderator *per se*, but in another place I did have maximum rep-based privileges unlocked on one site and m...
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almost 3 years ago
Comment Post #282642 If the quoted exercise is the true problem and this is an XY question, it's far simpler to consider the basic combinatorial meaning of $\binom{n}{k}$.
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almost 3 years ago
Comment Post #282645 Probably not. But if you interpret $\sum_{k=0}^n k \binom{2n}{k}$ in terms of choosing a team of up to $n$ people with one designated captain from $2n$ people then you can transform it into a sum which you're already familiar with.
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almost 3 years ago
Edit Post #282637 Initial revision almost 3 years ago
Answer A: A formal-logic formula for decimal to binary conversion
The formal formula for base conversion of a non-negative number is $$x = \left\lfloor \frac{x}{b} \right\rfloor b + (x \bmod b)$$ For binary, $b=2$.
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almost 3 years ago
Comment Post #281319 @DNB, the sum total of your edits seems to be to remove all MathJax content. If you refer to explaining to a primary school pupil, I think the correct response is probably "The subject is too advanced. Wait a few years," but since I've never tried to teach maths to primary school pupils I may be unde...
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almost 3 years ago
Edit Post #282564 Initial revision almost 3 years ago
Answer A: What story and TWO-digit Natural Numbers best fit Bayes' Theorem chart?
I flagged it as a duplicate. I don't recall seeing the subtle difference, and in any case it's your responsibility as the asker of both questions to put them in context with respect to each other: both of them link to an external site but don't mention the other question on this site. I still beli...
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almost 3 years ago
Comment Post #282286 You ask whether questions "like these" are considered on-topic, but give the example in a format which only moderators can actually read (a link to a deleted question). That doesn't seem very productive. (Although, FWIW, my attempt to reconstruct the question from clues in this meta-question suggests...
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almost 3 years ago
Comment Post #281724 Would I be correct in guessing that the lack of any comment on my answer is because you haven't seen the final version?
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almost 3 years ago
Comment Post #281987 This appears to be exactly the same as your earlier question https://math.codidact.com/posts/280741 , and certainly suffers the same flaw that I raised then in the comments which makes it unanswerable.
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almost 3 years ago
Edit Post #281764 Post edited:
Complete argument
almost 3 years ago
Edit Post #281764 Post edited:
Actually I was a bit too blithe in how easy it is to show congruence
almost 3 years ago
Edit Post #281764 Post edited:
almost 3 years ago
Edit Post #281764 Initial revision almost 3 years ago
Answer A: proving relative lengths on a secant
This image matches the description in the question (note that, in violation of what I consider to be conventional, $O$ is not the centre of the circle but the midpoint of $AD$). I add a perpendicular to $AD$ from $O$ which intersects $AC$ at $G$, and lines $OF$ and $DG$ which intersect at $H$. As ...
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almost 3 years ago
Edit Post #281319 Initial revision about 3 years ago
Answer A: How can I deduce which operation removes redundacies?
> 1. How can I deduce which operation ought fill in the red blank beneath? You can't. It's a hideous phrasing. The issue at question is not "redundancies" (which would carry the implication that they're merely unnecessary) but multiple counting: that is, counting the same assignment more than onc...
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about 3 years ago
Comment Post #280851 Do you have a definition of $\lim_{a \to \infty} f(a) = \infty$ in first order logic (i.e. as a simple statement with $\exists$ and $\forall$)?
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about 3 years ago
Comment Post #280741 How are you quantifying "contrast the base rate fallacy"?
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about 3 years ago
Comment Post #280639 @TechnologicallyIlliterate, yes. The wording around arbitrary constants and families of solutions indicates that you need to be more careful than just eliminating the common $y$. The $c$ is (32) is not necessarily equal to the $c$ in (33).
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about 3 years ago
Edit Post #280639 Post edited:
over 3 years ago
Edit Post #280639 Initial revision over 3 years ago
Answer A: Isn't it wrong to write that Indefinite Integral = Definite Integral with a variable in its Upper Limit?
> ${\int{f(t) \\; dt} = \int{t0}^t f(s) \\; ds \quad \text{ where $t0$ is some convenient lower limit of integration.}}$ isn't actually in the source text at all. Unpacking some of the surrounding text to more formal notation, it goes from equation (32) $$\exists c: \mu(t) y = \int \mu(t) g(t) \\...
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over 3 years ago
Comment Post #278332 For $n=3$ you want three rectangles of 1/3 by 1. Beyond there it gets more complicated; I suspect that the initial cuts will tend to leave a rough circle, but if so then IIRC some calculations I made a few months ago showed that the diameter of a sector sliced from the circle would eventually be grea...
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over 3 years ago
Comment Post #280068 @Derek Elkins, I would say that the key difference is that division by 2 isn't really division in binary floating point representations: it's subtraction applied to the exponent. (I'm sure you know this already, but I didn't think it came through clearly in the explanation).
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over 3 years ago
Comment Post #280118 To be clear: am I correct to understand that by "*the last two points*" you mean everything from "*and we define*" until the end?
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over 3 years ago
Comment Post #279400 What is the division ring in your "intuitive" instantiation?
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over 3 years ago
Comment Post #278431 Or the property $P(x) = x \not\in x$ cannot exist in such an axiomatic system, or such an axiomatic system can contain a set of all sets but at the cost of consistency, or possibly such an axiomatic system can contain a set of all sets as long as it doesn't have the law of the excluded middle.
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over 3 years ago
Comment Post #278270 Note to site admins: I haven't wrapped the multiline stuff in `$$` because it was rendering identically in the preview. IMO it would be a perfectly reasonable approach to look for/write a Markdown plugin to treat the MathJax delimiters `$` and `$$` as start and end delimiters of a section where escap...
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over 3 years ago
Comment Post #278270 @Derek, now that you mention it, I'd noticed that I had to escape the backslashes for backslash-curlybrace to get the multiset notation to work. I should have put 2 and 2 together myself. Thanks for the diagnosis.
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over 3 years ago
Comment Post #278269 @tommi, see https://math.codidact.com/q/278270
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over 3 years ago
Edit Post #278270 Initial revision over 3 years ago
Question MathJax config: newlines in eqnarray contexts
In my answer to https://math.codidact.com/questions/278268 I have a couple of `eqnarray` contexts which are being rendered by MathJax but aren't being broken into lines as they should. This works fine in other sites with MathJax which I used to use, so I suspect that it's a problem with the configura...
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over 3 years ago
Edit Post #278269 Initial revision over 3 years ago
Answer A: Asymptotics of counting integers by prime signature
Let $\alpha$ be the smallest exponent such that we know how to calculate $\pi(n)$ in time $\tilde O(n^\alpha)$. Courtesy of Deléglise and Rivat, who removed the $+ \epsilon$ from Lagarias, Miller and Odlyzko's bound, we know that $\alpha \le \tfrac23$, but I'm going to work in terms of $\alpha$ becau...
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over 3 years ago
Edit Post #278268 Initial revision over 3 years ago
Question Asymptotics of counting integers by prime signature
The prime counting function $\pi(n)$ which counts the number of primes up to $n$ is well-known, and it's also fairly well-known that using a well-optimised implementation of the Meissel-Lehmer algorithm it can be calculated in $\tilde O(n^{2/3})$ time. What about numbers of other forms? To be spec...
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over 3 years ago
Comment Post #278141 The case $k=1$ is also easy: we take $X = \max_{i=1}^n(X_i)$ and observe that for $x \in [1, s]$, $P(X \le x) = \left(\frac{x}{s}\right)^n$ because each independent die must roll no more than $x$. From that we can get $P(X = x)$ in closed form and $E(X)$ in terms of Faulhaber's formulas.
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over 3 years ago