darij grinberg

Mar 7 08:06
This is an instance of the identity $\sum\limits_{k=1}^n k \dbinom{n+1}{k+1} x^{n-k} = \left(n-x\right)\left(1+x\right)^n + x^{n+1}$, which holds for any number $x$. Various proofs are possible, e.g., by rewriting the factor $k$ on the left hand side as $\left(k+1\right)-1$. I wouldn't go looking for a combinatorial proof that works only for one value of $x$.
 
Nov 12, 2023 04:06
then your \sum_{\pi} part multiplies this by an additional column symmetrizer b_t
Nov 12, 2023 04:06
so you get a_t * read(t), where a_t is the row symmetrizer of t
Nov 12, 2023 04:06
ok, it is r*read(t)
Nov 12, 2023 04:05
or maybe read(t)*r
Nov 12, 2023 04:05
in order to embed the tabloid module into the group algebra, you have to send each tabloid {t} to the sum of r*read(t) over all row-permutations of t (where read(t) is the reading word of t in a specified reading order)
Nov 12, 2023 04:01
haha he doesn't even mention the ideal definition
Nov 12, 2023 04:00
Definition 2.5 is the polytabloid definition
Nov 12, 2023 04:00
i'd look at wildon's notes for a quick definition
Nov 12, 2023 04:00
does she define them?
Nov 12, 2023 03:59
i think these are equivalent
Nov 12, 2023 03:59
or by polytabloids in the tabloid module
Nov 12, 2023 03:58
either as the ideal generated by "row symmetrizer times column symmetrizer" in the symmetric group algebra
Nov 12, 2023 03:58
nah, they can be defined over any commutative ring
Nov 12, 2023 03:56
IMHO even the existence of a $\ZZ$-module basis is unknown
Nov 12, 2023 03:56
i'd love to hear some more results about them
Nov 12, 2023 03:55
yeah the specht_module class is for bad shapes, as in dspace.mit.edu/handle/1721.1/60196
Nov 12, 2023 03:55
if you have the time, would be worth looking at the yang-baxter construction of the specht rep, and check if it gives integer entries
Nov 12, 2023 03:54
its main purpose is to cover arbitrary diagrams (not just partitions)
Nov 12, 2023 03:53
it's very slow
Nov 12, 2023 03:53
keep in mind that this is a toy implementation of the definition with no tricks and shortcuts
Nov 12, 2023 03:53
ah yes, this is recent enough (note the 2023 year in the documentation)
Nov 12, 2023 03:48
Ah, right, specht_module works over any field (not sure how I had forgotten it, as I was the one reviewing that ticket IIRC). What exactly does not work?
Nov 12, 2023 03:48
@JacksonWalters: As long as the basis is a $\mathbb Z$-basis, this is true. Is it for the Sage implementation? I'd hope but I don't know.
Nov 12, 2023 03:48
@JacksonWalters: Please be aware that the only currently supported implementations of Specht modules in Sage are "seminormal", "orthogonal" and "Specht", and (to my knowledge) all of them are written in a way that presupposes at least characteristic $0$. (A pity if you ask me: at least Specht should know better...)
 
Jan 29, 2023 23:07
PS. Auditing students shouldn't affect a curve anyway, should they? If they do, IMHO that's another problem worth fixing.
Jan 29, 2023 23:07
You've rightfully called the students in question "clowns". If you can get this attitude across to your colleagues teaching the other sections as well as the best of your students, the clown circus will have to move out of town, because being widely seen as a clown does not make one popular with girls.
Jan 29, 2023 23:07
I don't know the details of your situation, but it sounds to me like a problem that should be addressed at its branches, not its roots: discipline/expel the actual harassers (contact the TIX office when you hear serious complaints); give the rest a public heads-up that they're mostly wasting time and their peacockery isn't necessarily making them popular (here you should get your colleagues on board: status is an echo chamber); make sure there isn't such a shortage of actual tutors that anyone has to rely on this unofficial help; and for hell's sake, stop curving down the exams.
Jan 29, 2023 23:07
Does it matter much that the student sex statistics are published? I can easily imagine the app designers got the idea from these numbers, but IMHO you don't need fine-grained data to know that life science majors skew female and consequently the service courses that are required for them will create, uhm, opportunities. Having numbers is just making the targeting a bit more precise.
 
Aug 19, 2022 20:15
@BryanKrause: Is it the part where he wants to keep publishing on his subject? Most professional academics would.
Aug 19, 2022 20:15
@BryanKrause: There is at least one ongoing case of a Russian nuclear physicist/engineer whistleblowing to gulagu.net; it's "more likely than you think", as the old meme says.
 
Aug 10, 2022 20:34
@ElizabethHenning: I'm not exactly writing a paper here; nor are you. But a post like the above, which is telling minorities to avoid showing any personality because everyone around is aiming at their necks, would need some good evidence that would probably show up in a google search like the one I did. Note that your claim that "in-groups get cut way more slack than out-groups" is much weaker than the one the post is making; I wouldn't be surprised if some studies confirm it, particularly when it comes to things like gaps in the CV. However, that's not xLeitix's claim!
Aug 10, 2022 20:34
... no literature whatsoever. Short of that, anecdotes? I'd be happy to hear some, but no one is telling!
Aug 10, 2022 20:34
... recent paper, again not specific to the academic job market, that finds a penalty for women that show "gender-incogruent" behavior on their CV (e.g., male-typical hobbies), and surprisingly a (slight) reward for men in the mirror scenario. That said, it relies on some predictive modeling magic rather than on actual reviewers; I'm not quite sure how much to think of it. In either case, I see very little that would apply to photography (which is maybe slightly female-coded) as a hobby. On the academic job market, I can find ...
Aug 10, 2022 20:34
@ElizabethHenning: There's a saying that anything stated without evidence can be dismissed without evidence. But let's actually look at the literature. The most relevant source I can find is a masters thesis by Kateryna Hunko from Linz which is concerned with non-academic hiring and finds a minor gender difference that flips depending on the type of hobby and the criteria applied. Then there is a ...
Aug 10, 2022 20:34
I'm asking for evidence of a claim you're making about academic hiring process, not of your academia.SE experience. As it stands, you are giving rather radical advice to minorities -- one that will likely damage their social life, because keeping your hobbies visible lets you meet friends -- on questionable factual footing.
Aug 10, 2022 20:34
Do you have any data on the minority relation, or is it just a guess?
 
Jan 14, 2022 12:45
@IanSudbery: "colonisation is when one people, polity or culture exerts power over another to replace the people, polity or culture and so make the colonising people, polity or culture the de facto norm" Nice characterization of the last 12 years of Democrat politics :)
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Jan 14, 2022 12:43
@IanSudbery (next comment): "why so few BAME students apply to our courses" has as many explanations as there are people suggesting explanations. Very little is understood about disparities in career choices; we haven't even figured out the gender-equality paradox ( en.wikipedia.org/wiki/Gender-equality_paradox ). At this point, it's a Rorschach test more than a scientific question. On a DEI committee, I assume it will come down to racism, but that's about how these committees tick.
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Jan 14, 2022 12:40
... From what I have seen on the "decolonial" side of the discourse, these issues are ignored entirely.)
Jan 14, 2022 12:39
... As to the issues with "genetic resources" (not quite sure which ones you are talking about), what does this imply for curricula? (These issues can be deeply non-straightforward; it is far from clear how to benefit a third world country that is governed by a hopelessly corrupt regime and/or in danger of societal collapse. What happened to the Mesopotamian archaeological finds returned to Iraq when ISIS came into town? ...
Jan 14, 2022 12:37
@IanSudbery: All examples are coming from biology in the wide sense, as I expected :) And the focus on first world diseases is indeed one thing where widening the course offerings is a good idea. But there is not really a scientific or moral necessity for it -- it's perfectly fine to argue that a university in a given country can choose to focus on the issues most prevalent in said country. It's just less of a wide focus than one could hope for. ...
Jan 13, 2022 21:54
@BryanKrause: Disparities start long before undergraduate admissions and are multifactorial. Why should curricula be the right lever to pull? (And it's absolutely weird to speak of colonialism when you are talking about things happening contemporarily.)
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Jan 13, 2022 21:08
@BryanKrause: Very little of this is relevant to STEM curricula. (I can think of some relevance in medicine, but it is probably better put into a different frame.)
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Jan 13, 2022 16:41
... that Diego de Landa has burned, nor to recover the lost books of the library of Baghdad. Trying to fill the gaps with "oral history" and activist speculation is no better than seeking cosmological constants in the dimensions of the Great Pyramid. As to the content of Western science, thousands of researchers from all over the globe easily joining its tradition (well, no less easily than us Westerners do so) are reason enough for me to believe its objectivity.
Jan 13, 2022 16:41
@JSLavertu: I have assumed that the OP is about STEM, even though it has been left unsaid. I do not want to claim too much about the humanities as there is a rather wide variety. In STEM, I stand to the claim that "colonialism" (even in the widest senses) is not embedded in the current curriculum to any extent that would warrant urgent removal (or "decolonization"). The fact that the history of Western science is better known than many parallel developments is well-understood, and has been so for decades, but unfortunately there is no way to unburn the manuscripts ...
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Jan 13, 2022 16:41
It is indeed rather "arrogant to propose that we can" remove something that is not there.
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Jan 14, 2022 03:21
... interests to the current decade's buzzwords (which happens far too often, but no one on academia.stackexchange would defend). So, no, it is not "how you will do your job well", no more than a physicist's "doing their job well" should include writing breathless grant proposals about deep learning and climate change.
Jan 14, 2022 03:21
@AnonymousPhysicist: An academic job is first and foremost about research, then about teaching, and finally about service, which can include many things from founding clubs through making expository videos to maintaining free software. On each of the three, we traditionally trust the academic to choose their path and merely see that something interesting and useful comes out in the end (scientific freedom). Expecting researchers to adapt their service interests to a narrow (if hyped to a fault) segment of contemporary politics is no better than expecting them to adapt their research ...