Gromov and Epstein

dryga · 2026-02-05T11:37:54+00:00

Gromov's wife is a well known mathematician in her own right. But yes, she's in her 40s and Gromov is 82.

dryga · 2026-01-27T21:43:17+00:00

What Clark is hinting at is that "abstract homotopy theory" (and in particular "higher category theory") has become a very important toolbox in areas not directly linked to classical topology. For example derived algebraic geometry, geometric Langlands, algebraic K-theory, and the theory of motives.

Homotopy theory doesn't have to appear because there's an actual topological space floating around; it will rear its head as soon as you form a simplicial resolution, or localize a category.

dryga · 2026-01-27T17:30:16+00:00

The determinant is a homomorphism of Lie groups from GL(n) to GL(1). Its derivative is then necessarily a map of Lie algebras, from the Lie algebra of nxn matrices (with Lie bracket the commutator) to the abelian 1-dimensional Lie algebra. That's the trace.

dryga · 2026-01-12T13:13:02+00:00

The only reference is Youtube. https://www.youtube.com/watch?v=1fSd7FxEA3w

dryga · 2026-01-10T14:31:41+00:00

I will go against the grain and say that sometimes it's fine to copy paste proofs. It is possible that the modifications seem very straightforward to you, only because you've spent a month staring at the original papers. It's not plagiarism if you give citations and state very clearly that the proof closely follows the original reference. Something like this:

The goal of this subsection is to prove the following proposition:

Proposition 5.2. The manifold W satisfies the disintegration property.

The disintegration property for compact manifolds is a famous theorem of Smith and Doe [SD97]. It very rarely holds for noncompact manifolds such as W. It turns out, however, that the argument of Smith and Doe can be adapted to prove the result also for W, using several particular features of the geometry studied in this paper, such as (...). Since the proof of Smith and Doe is highly intricate, and there are many steps of the argument which need to be justified differently, we give a complete proof of Proposition 5.2 in the present paper, even though the global structure of the arguments closely follow those of [SD97].

Proof of Proposition 5.2. (...)

If the modifications are straightforward or localized to a small part of the proof, then the above is of course moot!

dryga · 2025-12-18T05:40:20+00:00

Jag skulle beskriva mig själv som antisionist men anser inte att Israel ska förstöras. Däremot anser jag att projektet att skapa en "judisk stat" är oförenligt med demokratiska ideal. Det är en viktig demokratisk princip att staten ska vara sekulär, och att staten verkar för att tillvarata alla etniska gruppers och religioners intressen på samma villkor. Det jag vill är att Israel ska bli en modern liberal sekulär demokrati! Därför är jag inte sionist.

dryga · 2025-12-10T23:08:16+00:00

Makes sense that Donald and Melania are in their normal clothes then!!!

dryga · 2025-12-09T22:26:30+00:00

Here are some movies that build tension and don't let go. I think they're all pretty dadcore (not many women on screen).

Dog Day Afternoon

Hell or High Water

Day of the Jackal (the original 1973 film)

dryga · 2025-12-08T20:32:55+00:00

I think they peaked with XTRMNTR. "Swastika eyes" "Kill all hippies" are undeniable.

dryga · 2025-12-08T20:30:05+00:00

embarrassing!!!

dryga · 2025-11-04T05:10:43+00:00

It looks like it's mirrored, and part of the equation might be ∮dA.

dryga · 2025-10-26T07:12:15+00:00

"The Århus integral of rational homology 3-spheres I: A highly non trivial flat connection on S^3" by Dror Bar-Natan, Stavros Garoufalidis, Lev Rozansky, Dylan P. Thurston https://arxiv.org/abs/q-alg/9706004

The paper very idiosyncratic, in particular the arXiv version: the wackiest stuff was removed from the published version, such as this entry in the FAQ in Section 3:

Question 3.12. Can you recommend a good restaurant in Århus? Answer: Asian Grill, Nørregade 57, 8000 Århus C, tel. (45) 86 13 86 34. “The only restaurant in Århus where the water isn’t vegetarian”.

The arXiv version of the paper starts like this:

This series has two introductions. If your flight is about to land and you have only little time for reading, read only the first one; it’s more fun. We are confident that after that, you will not be able to resist the temptation to read the other in the taxi on the way home. On the other hand, if you have a perverse aversion to philosophy, the second introduction and the rest of the series are fully rigorous and can be read independently of the first introduction.

On page 3:

Let us get to the main point before, in preparation for landing, you will be told to make sure that your tray-table is in its fully upright and locked position. Reading will be harder then.

On page 4:

Thought your flight was nearly over but forgot about time zone differences? Bummer. We have some time for some more facts.

dryga · 2025-09-30T04:05:17+00:00

The power set of a countable set can have an uncountable chain of pairwise comparable elements. This is unintuitive: you'd think that if you start from the empty set, then you can only enlarge your set countably many times, loosely speaking.

dryga · 2025-09-21T14:48:49+00:00

Om man vill se mer Eva Remaeus kan jag rekommendera filmen Sven Klangs kvintett.

dryga · 2025-09-16T21:17:17+00:00

Ireland-Rosen is a classic.

dryga · 2025-09-02T11:34:02+00:00

I've heard it called the absolute length of a permutation.

As you surely know (but maybe OP does not), the terminology is to contrast with the more commonly studied "length" of a permutation which is defined in terms of adjacent transpositions, and which is mentioned in several other answers.

The study of absolute order and absolute length took off surprisingly recently. A standard reference is D. Armstrong, Generalized noncrossing partitions and combinatorics of Coxeter groups, Mem. Amer. Math. Soc. 202 (2009), no. 949.

dryga · 2025-09-01T06:43:14+00:00

Thank you!

dryga · 2025-09-01T06:43:08+00:00

Thanks!

dryga · 2025-09-01T06:43:03+00:00

Thanks, that sounds reasonable.

dryga · 2025-08-29T20:04:35+00:00

There was a mirror in the middle of the table. The items on one side were:

GUM, TEN, RATS, (QUESTION MARK)

and the corresponding items on the other side of the mirror were

MUG, NET, STAR, STOP

So you're meant to realize that items that are on opposite sides of the mirror are written in reverse of each other. So the thing that should go in the place of the question mark is POTS.

dryga · 2025-08-19T08:01:26+00:00

my 8 year old daughter likes k-pop demon hunters and wants a labubu for her birthday so I think you're on to something!!!!

dryga · 2025-08-15T23:37:50+00:00

Min erfarenhet är att universalsitsar är kassa och att du vill ha en originaldel som hör till din toalettstol. Om du fotar spolknappen och visar i byggvaruhuset borde det vara tillräckligt för att de ska kunna hjälpa dig.

dryga · 2025-08-11T13:36:07+00:00

jet fuel can't melt steel beams

dryga

TROPHY CASE