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147 votes
21 answers
23k views

Are there examples of non-orientable manifolds in nature?

Whilst browsing through Marcel Berger's book "A Panoramic View of Riemannian Geometry" and thinking about the Klein bottle, I came across the sentence: "The unorientable surfaces are never discussed ...
79 votes
9 answers
21k views

Results that are widely accepted but no proof has appeared

The background of this question is the talk given by Kevin Buzzard. I could not find the slides of that talk. The slides of another talk given by Kevin Buzzard along the same theme are available here. ...
43 votes
11 answers
15k views

Open questions in Riemannian geometry

What are some major open problems in Riemannian Geometry? I tried googling it, but couldn't find any resources.
27 votes
10 answers
2k views

Examples of Kan extensions, adjunctions, and (co)monads in analysis, Lie theory, and differential geometry?

In introductory texts on category theory, it seems like the majority of examples come from algebraic topology, algebra, and logic. What are some good examples of Kan extensions, adjunctions, and (co)...
22 votes
1 answer
3k views

What is so special about Chern's way of teaching?

First of all sorry for this non-research post. I was watching Jeffrey Blitz Lucky documentary movie and it was interesting to me that a winner of Lottery was a math Ph.D. from Berkeley. In the movie ...
C.F.G's user avatar
  • 4,195
16 votes
3 answers
3k views

group of diffeomorphisms of a manifold

How much has been the group of diffeomorphisms of a manifold " been studied. I got this information from wiki. " Quite a lot is known about the group of diffeomorphisms of the circle. Its Lie algebra ...
Koushik's user avatar
  • 2,106
5 votes
5 answers
2k views

Terminology introduced in recent years with more than one meaning

Suppose a term(inology) is recently (in last 20 years) introduced in research mathematics. It might happen that some one who wish to use it, in the same area of research, for different purposes or ...
4 votes
0 answers
421 views

What are your common strategies/remedies when your new theory/idea stuck in most cases?

Sorry if this is not a suitable post for MO. Sometimes after reading the origin of a theory/idea in differential topology I put myself in the shoes of that mathematician and ask myself, Did you do the ...
C.F.G's user avatar
  • 4,195
4 votes
0 answers
653 views

Research topics in Curves and Surfaces [closed]

I advance that I'm not a mathematician but I'm an undergraduate student of mathematics. In my courses at university I have studied a bit of Differential Geometry, in particoular differential geometry ...
Vincenzo Zaccaro's user avatar