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14 votes
0 answers
414 views

Does the category of G-spectra know G?

I was recently in the situation of having access to the category of $G$-modules (for some group $G$ which I had forgotten), as just a category, i.e. no monoidal structure, together with the forgetful ...
Vivek Shende's user avatar
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9 votes
0 answers
317 views

Are there non-obvious finite $E_\infty$ ring spectra?

I see two "obvious" classes of nonzero finite $E_\infty$ ring spectra $R$: $R = \Sigma^\infty_+ (S^1)^{\times n}$ $R = D\Sigma^\infty_+ X$ ($X$ a finite space) Questions: Are there any others? In ...
Tim Campion's user avatar
8 votes
0 answers
300 views

What can I say about an $E_\infty$ ring spectrum with an odd invertible element?

I have an $E_\infty$ ring spectrum $R$. I suspect it is trivial, but I'm not sure. What I do know is that there is an $R$-linear equivalence $R \simeq \Sigma R$. Unless I am very confused, this ...
Theo Johnson-Freyd's user avatar
8 votes
0 answers
328 views

Did the Goerss-Hopkins manuscript "Multiplicative stable homotopy theory" ever appear?

A citation to "M. J. Hopkins and P. Goerss, Multiplicative stable homotopy theory, unpublished manuscript, 1996" appears in the Hill, Hopkins, Ravenel Annals paper on the Kervaire invariant. It was ...
David White's user avatar
  • 30.3k
7 votes
0 answers
223 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
6 votes
0 answers
155 views

Homotopy groups of certain geometric fixed point spectrum

Let $G$ be a finite group and $E$ be a genuine $H$-spectrum for $H\leq G.$ Then for any subgroup $K$ of $G$, consider the $K$-spectrum $X=Res^G_K Ind^G_H(E).$ Is there any reference for computing the ...
Surojit Ghosh's user avatar
6 votes
0 answers
201 views

Which ring spectra are homotopy limits of simpler ones?

Most surely I will tag this by reference request: I am sure very much is known about this question, I am just too ignorant to even guess where to look. What makes me feel especially foolish is the ...
მამუკა ჯიბლაძე's user avatar
5 votes
0 answers
210 views

Dependence of completion on the base ring

Let $M$ be a module over an $E_\infty$ ring, $A$. Let $I$ be an $A$-non unital commutative algebra together with an associative map $I \wedge_A M \to M$. Define ${_A}(M/I^n)$ as the cofiber of $I^{\...
Hari Rau-Murthy's user avatar
5 votes
0 answers
173 views

Uniqueness of complex topological $K$-theory as an $S$-algebra

This might be well-known or trivial, but I could not figure out how to fill in the details: For an $S$-algebra $K$ denote its associated multiplicative cohomology theory by $h^*_K$. Suppose that I ...
Ulrich Pennig's user avatar
5 votes
0 answers
229 views

Bockstein morphism of spectral sequences

Given an omega spectrum $E$, there is a type of chern character map given by its rationalization $$r:E\to E\wedge M\mathbb{R}\;,$$ where $M\mathbb{R}$ denotes a Moore spectrum. The cofiber of the map $...
Daniel Grady's user avatar
4 votes
0 answers
196 views

Valuations and (semi)norms on ring spectra

Valuations and seminorms on rings play a big role in number theory and analytic geometry, with seminorms being heavily used in Berkovich geometry and valuations featuring heavily in adic geometry. Let'...
Emily's user avatar
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4 votes
0 answers
294 views

Can one define fields in stable homotopy theory via invertibility?

In Nilpotence in Stable Homotopy Theory II, Hopkins–Smith define a field spectrum to be a ring spectrum $E$ such that $E_*X$ is a free $E_*$-module for all spectra $X$. They then show that any field ...
Emily's user avatar
  • 11.8k
4 votes
0 answers
376 views

matrix ring spectra

I am trying to understand matrix ring spectra. Apparently, I have two different definitions of those and I did not manage to show that they are equivalent - maybe they even are not in the general case....
Ulrich Pennig's user avatar
3 votes
0 answers
284 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
3 votes
0 answers
434 views

Units of a ring spectrum

Is there a good notion of the spectrum of units $R^\ast$ in a (possibly non-connective) $E_\infty$-ring spectrum $R$? A standard definition (see section 1.2 in http://arxiv.org/abs/0810.4535) seems ...
unit's user avatar
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