Homotopy Theory

A room for anyone interested in homotopy theory, or any nearby...
May 4, 2018 22:29
If you started with a chain complex in an abelian category, then the spectral sequence you get out has to degenerate at E_1, and I'm guessing that means that the objects F(i, j) are zero whenever j - i > 2
May 4, 2018 22:29
A chain complex in a stable category gives you, in particular, a filtered object, and as Lurie discusses, the objects F(i, j) for general i and j are related to the higher pages of the resulting spectral sequence
May 4, 2018 22:21
Yeah, I'm sure something like that is possible
May 4, 2018 22:19
But if you pursue those coherences, you must end up writing down something like Gap
May 4, 2018 22:19
But if you're in the nerve of a 1-category, then you don't need the coherences
May 4, 2018 22:18
That much makes sense in any pointed oo-category, I guess
May 4, 2018 22:18
You can write down a sequence of objects in a stable oo-category with boundary maps such that d^2 = 0, but then there are a bunch of coherences you have to put in, because d^3 otherwise might be zero in two different ways
May 4, 2018 22:16
Yeah, I think that's exactly right
May 4, 2018 22:16
which is in D(Ab), not (Ab)
May 4, 2018 22:16
It seems from 1.2.2.3 that if your complex is ...->C_n -> C_{n - 1} -> ..., then if F is the corresponding object of Gap, F(n - 1 , n) = C_n[n]
May 4, 2018 22:11
If you start with a complex in an abelian category, though, I think your Gap object will take values in the derived category
May 4, 2018 22:10
That shows how an object of Gap gives you something recognizable as a chain complex
May 4, 2018 22:09
I think you want Remark 1.2.2.3
May 4, 2018 22:04
No, I could have figured that out
May 4, 2018 22:04
Ah, right
May 4, 2018 22:04
Of which work?
May 4, 2018 22:03
Where does he talk about Gap?
Mar 27, 2018 05:57
well, the arxiv seems to be back
Mar 26, 2018 17:50
Which is the same thing as product-preserving presheaves
Mar 26, 2018 17:50
It's the nonabelian derived category - freely generated under sifted colimits
Mar 24, 2018 18:05
Right
Mar 24, 2018 17:11
I think the connected Z/n-covering spaces correspond to the surjective morphisms \pi_1(X) -> Z/n
Feb 4, 2018 19:03
Hasn't the discourse up till now been that that isn't possible?
Feb 4, 2018 19:03
It looks like he gives a moduli-theoretic interpretation of Morava E-theory in terms of a theory of formal groups on commutative ring spectra
Dec 8, 2017 16:21
I don't know how plausible that seems to me, but some rich and powerful people seem to want to make it happen, because there was a link to the breakthrough prizes from the main google search page the other day
Dec 8, 2017 16:20
@JonathanBeardsley there is a potential utilitarian calculus here. It could be argued that if the breakthrough prizes really "arrive" in the public consciousness, they could raise the profile of math enough to draw vastly more funding than their cost
Nov 30, 2017 20:50
and someone, I think Tyler, recently told me there's one known as "the multi-author paper" too
Nov 30, 2017 20:49
there are two classical papers in homotopy theory that get referred to simply as "the five-author paper" and "the six-author paper"
Nov 20, 2017 19:08
Or actually, must a quotient of cohomological Mackey functors be cohomological?
Nov 20, 2017 19:07
That's true, the homology Mackey functors have to be cohomological
Nov 20, 2017 19:07
Do you know for sure that those two things are different?
Nov 15, 2017 17:41
Ah, I think what I was half-remembering is that a generic A_oo structure on Morava K-theory isn't homotopy commutative
Nov 15, 2017 17:39
Oh sure
Nov 15, 2017 17:38
I think Angeltveit also shows that a "generic" A_oo structure on Morava K-theory doesn't extend to an E_2 structure
Nov 15, 2017 16:55
there's always the stable module category, which is secretly a category of module spectra but you don't have to think about it that way
Oct 21, 2017 23:03
It looks like it's a livestream of a memorial event for Mirzakhani at Stanford
Oct 10, 2017 21:16
definitely not
Oct 10, 2017 16:29
Surely a representable functor from spectra to spectra is linear?
Oct 6, 2017 13:18
I have the strong impression there are very few, but I don't have a precise answer. I'd also like to know
Oct 1, 2017 19:21
Which is some kind of cyclotomic object, and then you could lift it to the corresponding TC
Oct 1, 2017 19:20
One might guess that the topological analog of the trace lands in the cohomology of the free loop space
Sep 29, 2017 20:42
aren't those two groups equal by definition?
Sep 28, 2017 15:53
presumably examples of non-left-complete t-structure come from stabilizing non-hypercomplete topoi or something
Sep 28, 2017 15:53
right
Sep 28, 2017 15:50
that's exactly the argument I was going to give that spectra are right complete, so I don't know why I didn't notice that it works both ways
Sep 28, 2017 15:49
good - sorry for misleading with my mistake earlier
Sep 28, 2017 15:49
ah, right
Sep 28, 2017 15:46
but maps between pro-objects aren't necessarily the same as maps between the limits, right?
Sep 28, 2017 15:45
if so, is that, in fact, true?
Sep 28, 2017 15:45
ok, let's see - is it the case that left completeness is equivalent to the mapping space between the Postnikov systems being equivalent to the mapping space of spectra?