Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options not deleted user 7108

Homotopy theory, homological algebra, algebraic treatments of manifolds.

8 votes
Accepted

$ \mathbb{R}P^n $ bundles over the circle

Your answer is correct if appropriately understood, but it's a little subtle. Here I should note that I'm interpreting your question as a purely homotopy theoretic one (in particular ignoring smooth s …
Dmitry Vaintrob's user avatar
8 votes
0 answers
141 views

singular homology of manifold with corners

Given two smooth manifolds with corners, let's say that a map $f:X\to Y$ is "transversally smooth" if it is smooth in the usual sense and if (in a local sense on $X$) for every open Whitney stratum $S …
Dmitry Vaintrob's user avatar
6 votes
0 answers
121 views

Recovering operad units from homotopy units

It is my understanding that the $\infty$-category of non-unital connected topological monoids is equivalent to the $\infty$-category of connected topological groups. It follows that the functor from u …
Dmitry Vaintrob's user avatar
10 votes
0 answers
340 views

Hodge structure and rational coefficients

Suppose $X$ is a complex projective variety with a model $X_\mathbb{Q}$ defined over the rational numbers. Then there is a rational de Rham lattice $H^k_{dR}(X_\mathbb{Q}, \mathbb{Q})\subset H^k(X, \m …
Dmitry Vaintrob's user avatar
7 votes
0 answers
215 views

Duality of Hopf algebras and duality of spectra

Let $S$ be the sphere spectrum, and for $X$ a topological space, let $S(X)$ be the mapping spectrum from the free loop spectrum on $X$ to the sphere spectrum. This is an $E_\infty$ ring spectrum (also …
Dmitry Vaintrob's user avatar
8 votes
1 answer
597 views

How much of the category of motives can be recovered from automorphisms of the Betti functor

Say we are working with schemes over a field $k\subset \mathbb{C}.$ A motive in the sense of Voevodsky is a functor $Sch\to D^bVect$ from (an appropriate category of) schemes to the DG category of com …
Dmitry Vaintrob's user avatar
4 votes
1 answer
283 views

Weak homotopy equivalence of sites

There are several notions of weak homotopy equivalence for topological spaces. The standard one can be formulated as follows: a map of spaces $X\to Y$ is a homotopy equivalence if the map of simplicia …
Dmitry Vaintrob's user avatar
2 votes
1 answer
205 views

Is the Hurewicz model category left proper?

A model structure is left proper if the pushout of a weak equivalence along a cofibration is a weak equivalence. In the Hurewicz (or Strom) model structure on the category of topological spaces, weak …
Dmitry Vaintrob's user avatar
6 votes
1 answer
302 views

Homotopy equivalence between two basepoints of the etale homotopy type of the one-torus

Let $T = \mathbb{G}_m$ be the torus, and let $\tilde{T}$ be its étale universal cover (a pro-object in schemes of finite type). Then both $T$ and $\tilde{T}$ have a well-defined étale homotopy type. E …
Dmitry Vaintrob's user avatar
5 votes
0 answers
221 views

"Strict" homotopy theory of topological stacks/orbifolds

If we fix a finite group $G$, there are two different useful homotopy theories on the set of $G$-equivariant topological spaces (which are CW complexes, say). One, the "weak" homotopy theory, is given …
Dmitry Vaintrob's user avatar
3 votes
1 answer
476 views

Monoidality of truncation of spectra

If $X$ is a spectrum, we have a notion of its connective part $X_{\le 0}$ and the corresponding notion of truncation $X_{[i:j]} = X_{\le j}/X_{\le i-1}$, where $X_{\le j}$ is deduced from $X_{\le 0}$ …
Dmitry Vaintrob's user avatar
31 votes
1 answer
2k views

A modern interpretation of Quillen's computation of the K theory of finite fields

In his beautiful paper On the cohomology and K theory of the general linear group over a finite field, Quillen constructs (if I understand correctly) an isomorphism on connected components of K-theory …
Dmitry Vaintrob's user avatar
3 votes
0 answers
83 views

Twists of equivariant spectra

Let $A$ be a spectrum, defined by deloopings $A_n$ (n an integer). Then the identity $A = S^1\wedge A_1$ together with antipodal equivariant spectrum structure on $S^1$ gives genuine $\mathbb{Z}/2$-eq …
Dmitry Vaintrob's user avatar
3 votes
0 answers
277 views

Can ring spectra be thought of as some sort of operad in $Top$?

It is a result of May's work on operads that the homotopy category (or $\infty$-category, if you prefer) of connective spectra is equivalent to a full subcategory of the category of representations of …
Dmitry Vaintrob's user avatar
13 votes

What is modern algebraic topology(homotopy theory) about?

I'm going to give an algebraist's perspective. First let's discuss homological algebra (which has roots in topology). There's a quote (attributed, I think, to Connes) that a great mystery of homologic …

15 30 50 per page