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Questions that are about research in mathematics, or about the job of a research mathematician, without being mathematical problems or statements in the strictest sense. Do not use this tag for easy or supposedly easy mathematical questions.

0 votes

Obscure Names in Mathematics

The Hauptsatz (due to Gentzen).
3 votes

What's a great christmas present for someone with a PhD in Mathematics?

A book of interviews of famous mathematicians could be good. I have in mind particularly More Mathematical People, which I've gotten a lot of mileage from here at MathOverflow.
29 votes

Is a come back to mathematical research possible?

I hesitate to posit myself as an example, but I was out of academia from 2001 to 2019, when I decided to become a stay-at-home dad while my wife became the breadwinner. (I won't go into the details of …
9 votes

Examples of notably long or difficult proofs that only improve upon existing results by a sm...

The following example is described in The Man Who Loved Only Numbers by Paul Hoffman. There is a reasonably short proof, found by Esther Klein (later Szekeres) in 1932, that given 5 points in the pl …
23 votes

'Category-theory'-free areas of pure math, 'category-theory'-loaded areas of applied math

I would upvote Keerthi's comment multiple times if I could. Just find an area of mathematics that makes you smile and brings you happiness. If in the course of doing research you find that you need to …
15 votes

Categorification request

I tried to discuss this geometric series example of categorification in one of my answers to another MO question by Jan Weidner, here. I can't tell whether this reply was considered unsatisfactory, bu …
Todd Trimble's user avatar
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14 votes

What are some examples of colorful language in serious mathematics papers?

From Jim Stasheff's Homotopy Associativity of H-spaces I, the magisterial-sounding To study spaces which admit $A_n$-structures, we can work directly with the maps…. In the case of a topological gro …
3 votes

Major mathematical advances past age fifty

Charles Sanders Peirce (born 1839) explicitly declared his Existential Graphs (all three parts: Alpha, Beta, and Gamma) to be his chef d'oeuvre. This work on graphical logic began sometime in the earl …
14 votes

Problems where we can't make a canonical choice, solved by looking at all choices at once

General topology as found in textbooks seems to be chock-full of examples where the axiom of choice seems to be (unconsciously?) invoked, and unnecessarily if one follows Eilenberg's advice to avoid s …
12 votes

Are there any "related rates" calculus problems that don't feel contrived?

Here's something you could try, based on a passage from Richard Feynman's "Surely You're Joking, Mr. Feynman!": When I was in high school, I'd see water running out of a faucet growing narrower, …
6 votes

Categories of finite objects

I would say you could make good headway on this by looking over some of the research projects of Tom Leinster, Mark Meckes, and Simon Willerton (and others I may be forgetting), centering on various n …
8 votes

Individual mathematical objects whose study amounts to a (sub)discipline?

The braid group. The Monster group. The Steenrod algebra. The representation ring of the symmetric group.
16 votes

A map of non-pathological topology?

I'll go ahead and say that Polish spaces are an interesting and almost sui generis class. There is a rich literature of applications to and from descriptive set theory, with layers of "pathology" hier …
Todd Trimble's user avatar
  • 53.3k
8 votes
Accepted

Concise definition of subobjects

Of course it's not necessary to make this identification, but it's fairly harmless since the groupoid of monomorphisms into an object $X$ is equivalent to the discrete category of subobjects, and it c …
Todd Trimble's user avatar
  • 53.3k
13 votes

Where is number theory used in the rest of mathematics?

Julia Robinson proved that the theory of fields is undecidable by showing that the natural numbers form a subset of the rationals definable by a first-order formula in the language of fields. The cons …

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