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Homotopy theory, homological algebra, algebraic treatments of manifolds.

7 votes
1 answer
2k views

Which revolutions in topology and geometry can we expect in the next 20 years? [closed]

In my limited perspective on the history of mathematics, I can name at least two big revolutions in Topology and Geometry (broadly construed): the introduction of Schemes in Algebraic Geometry, and th …
6 votes
1 answer
365 views

Different flavours of Vassiliev Conjecture

There is something that puzzles me about "Vassiliev's Conjecture". I am sure I am missing some detail which is obvious to the community, since there are several tightly related kind of results around …
Andrea Marino's user avatar
5 votes
1 answer
346 views

Analogues of Sullivan Theory at a prime for coformality

In rational homotopy theory, one can study the rational homotopy and cohomology categories via an algebraic structure, respectively the rational Lie Algebra model and the Sullivan cdga model. If I am …
Andrea Marino's user avatar
2 votes
0 answers
281 views

Notation for spectral sequences [closed]

Every single spectral sequence I have seen in my life was denoted by $E$. Even when there is more than one spectral sequence, people tend to use the same letter with some workaround (e.g. a fourth sub …
Andrea Marino's user avatar
4 votes
0 answers
243 views

Being a product - from homology to topology

The famous Kunneth formula expresses the homology of a product manifold as the tensor product of the two algebras. Now suppose we know that a manifold $X$ has a decomposition $H_*(X) \simeq A \otimes …
Andrea Marino's user avatar
12 votes

Why should an algebraic geometer care about singular / simplicial (co)homology?

The very advantage of algebraic topology over algebraic geometry is the existence of a segment. From a segment it's easy to construct triangles, tetrahedra, and simplices in general. There are at leas …
Andrea Marino's user avatar
4 votes
1 answer
182 views

Homotopy coherent space maps induces homotopy coherent chain complex morphisms

It is an elementary fact that a map $f:X \to Y$ between spaces induces a chain complex morphism $f_* : C_*(X) \to C_*(Y) $. This allows one to transfer 1-category theoretic arguments from spaces to as …
Andrea Marino's user avatar
4 votes
0 answers
418 views

Persistent homotopy groups

Everybody in algebraic topology loves homology and cohomology, but sometimes we like homotopy groups also, since they detect different things (think about spheres) . An interesting and recent applicat …
Andrea Marino's user avatar
6 votes
2 answers
522 views

Deformation of a diagram preserve the homotopy limit

I have been a bit sloppy in the title, but let me be specific. I stepped again into the subtle difference between homotopy limit and limit in the homotopy category, in the following version. Suppose y …
Andrea Marino's user avatar
1 vote
0 answers
118 views

1-connected infinity groupoids, groupoids and 1-connected spaces

I am exploring a bit the world of groupoids. What I have in mind is that infinity groupoids correspond to spaces. So my first question is the following: Consider the model category $\infty-Grpd$ of …
Andrea Marino's user avatar
1 vote

Definition of Left Operadic Kan Extension for $\infty$-operads

A recommendation: make drawings of cones! Note that by definition $$ (X_{/b})_n = Hom_b((\Delta^n)^{\triangleright},X)$$ Where $Hom_b$ means maps that sends the cone point to b. By Yoneda Lemma we c …
Andrea Marino's user avatar