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3 votes
2 answers
301 views

How to construct $X \oplus \Sigma X$ from $X \oplus \Sigma X \oplus \Sigma X \oplus \Sigma^2 X$ without splitting an idempotent?

Let $Z$ be an object in a stable (or triangulated/whatever) category $\mathcal C$. I believe it follows from Thomason's theorem (see The classification of triangulated subcategories) that the ...
Tim Campion's user avatar
  • 62.6k
6 votes
1 answer
550 views

Cobordism cohomology of Lie groups

Are there any results about cobordism cohomology of Lie groups?For example, $\mathrm{MU}^*(\mathrm{SU}(n))$.
wushilp's user avatar
  • 61
4 votes
0 answers
152 views

Are telescopes Noetherian?

Let $p$ be a prime and $h \in \mathbb N$ a height. Question 1: Does there exist a compact $T(h)$-local spectrum $A$ with a unital multiplication making $\pi_\ast A$ a Noetherian ring? A priori it's ...
Tim Campion's user avatar
  • 62.6k
4 votes
0 answers
177 views

Spanier-Whitehead dual of space of natural transformations

Let $F, G: \mathcal{J} \to \mathsf{Sp}$ be continuous functors between $\sf{Sp}$-enriched categories, where $\sf{Sp}$ denotes any of the point-set models for spectra (i.e., orthogonal spectra). ...
stableunknown's user avatar
14 votes
1 answer
344 views

The first two $k$-invariants of $\mathrm{pic}(KU)$ and $\mathrm{pic}(KO)$

$\DeclareMathOperator\Pic{Pic}\DeclareMathOperator\pic{pic}$Real and complex topological $K$-theories, $KO$ and $KU$, have Picard spectra $\pic(KO)$ and $\pic(KU)$ built from the $\mathbb{E}_\infty$-...
Jonathan Beardsley's user avatar
14 votes
2 answers
700 views

When is a stable $\infty$-category the stabilization of an $\infty$-topos?

Let $\mathcal X$ be a presentable $\infty$-category. Then the stabilization $Stab(\mathcal X)$ of $\mathcal X$ is the universal presentable stable category on $\mathcal X$. Conversely, if $\mathcal A$ ...
Tim Campion's user avatar
  • 62.6k
3 votes
1 answer
163 views

Which positive flat stable model structures on (flavors of) spectra have the property that cofibrant operad-algebras forget to cofibrant spectra?

Let $M$ be a monoidal model category and $O$ an operad valued in $M$, and the category of $O$-algebras inherits a model structure from $M$ where a map $f$ is a weak equivalence (resp. fibration) if ...
David White - gone from MO's user avatar
5 votes
1 answer
316 views

Is there a model structure for S-modules such that cofibrant operad-algebras forget to cofibrant S-modules?

In 1997, Elmendorf, Kriz, Mandell, and May wrote a book Rings, Modules, and Algebras in Stable Homotopy Theory in which they introduced the category of $S$-modules as a model for the stable homotopy ...
David White - gone from MO's user avatar
33 votes
2 answers
2k views

What happened to the last work Gaunce Lewis was doing when he died?

In 2006, Gaunce Lewis died at the age of 56. He'd done important work setting up equivariant stable homotopy theory, and I think it's fair to say his work was far ahead of its time. In recent years, ...
David White - gone from MO's user avatar
15 votes
3 answers
745 views

"Phantom" non-equivalences of spectra?

I would like an example of the following situation, or a proof that no such example exists. $\textbf{Situation}$: Two connective (EDIT: I'm fine with dropping this condition) spectra $X$ and $Y$ such ...
kiran's user avatar
  • 2,012
4 votes
1 answer
172 views

$BP$-Adams Novikov Spectral Sequence or Homotopy groups of $S/3$

What is know about the homotopy groups of $S/3$ where $S/3 = \mathrm{hocofib}(S \xrightarrow{\cdot 3} S)$? Otherwise, is there some reference I can consult for the $BP$-ANSS for $S/3$?
Jordan Levin's user avatar
8 votes
1 answer
467 views

Is there a Dold-Kan theorem for circle actions?

There are several interesting equivalences of "Dold-Kan type" in the setting of stable $\infty$-categories. Namely, let $\mathcal C$ be a stable $\infty$-category. Then the following 3 ...
Tim Campion's user avatar
  • 62.6k
5 votes
1 answer
393 views

Thom spectra, tmf, and Weierstrass curve Hopf Algebroid

Let $X(4)$ be the Thom spectrum associated to $\Omega SU(4) \to \Omega SU \simeq BU$. Since $X(4)$ is a homotopy commutative ring spectrum, for any spectrum Y we can construct a resolution $$ Y \wedge ...
Tominaga's user avatar
  • 141
4 votes
0 answers
124 views

What is the colimit closure of the finite endomorphism spectra?

$\newcommand{\colim}{\operatorname{colim}}\newcommand{\finend}{\operatorname{finend}}$Let $F$ be a finite spectrum. Then $\operatorname{End}(F) = D(F) \wedge F$ is also finite. Question: Which spectra ...
Tim Campion's user avatar
  • 62.6k
8 votes
1 answer
637 views

$E$-(co)homology of $BU(n)$ (Reference request)

I am currently reading Lurie's notes on Chromatic Homotopy Theory (252x) and in Lecture 4 (https://www.math.ias.edu/~lurie/252xnotes/Lecture4.pdf), he skims through the calculation of $E^{\ast}(BU(n))$...
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