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Homotopy theory, homological algebra, algebraic treatments of manifolds.

3 votes

Historical transition from classical homotopy to modern homotopy theory

This is not an answer, but a little too long for a comment. Scott, what a list: 3 dead, 2 retired, and me; also I think Mike and I are always on the same side of the fence. As to the original questi …
1 vote

Operad terminology - Operads with and without O(0).

A 2020 paper Operads, monoids, monads, and bar constructions by Ruozi Zhang, Foling Zou, and J.P. May revisits the foundations of operad theory and discusses several possible choices for what $\mathca …
Peter May's user avatar
  • 30.4k
2 votes

Is there a recognition principle for $\mathbb{E}_{\infty}$-spaces with zero?

I see no real point in considering $E_{\infty}$ spaces with $0$ except in the context of the multiplicative structure of an $E_{\infty}$ ring space or, essentially equivalently, the multiplicative str …
Peter May's user avatar
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7 votes
Accepted

Different ways to “deloop” a (topological) $A_\infty$-algebra

There are two old papers that address this topic in some detail: R. W. Thomason. Uniqueness of delooping machines. \url{https://projecteuclid.org/euclid.dmj/1077313403} Z. Fiedorowicz. Classifying …
Peter May's user avatar
  • 30.4k
4 votes

Why study infinite loop spaces?

There is so much much more. For one historical starting point among many, you see that many spaces of interest are infinite loop spaces and that tells you how to calculate things about them. For jus …
Peter May's user avatar
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8 votes
Accepted

Examples of non-zero negative Steenrod operations

Notice the switch in grading from homology to cohomology on May's page 182: $P^s(x) = P_{-s}(x)$. Operations that raise degree when graded homologically lower degree when graded cohomologically. A la …
Peter May's user avatar
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6 votes
Accepted

Model categories and chain complexes

I'll take your question as license to advertise a relatively recent paper in a slightly more specialized but concretely calculational direction: http://nyjm.albany.edu/j/2014/20-53p.pdf. Its title …
Peter May's user avatar
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11 votes

Incorrect information in an old article about the Kervaire invariant

I'm feeling mischievous. The history of the Kervaire invariant problem is strewn with false proofs, Jim Milgram's is only one of many. A student of mine (who I will leave nameless) had a preprint (a …
Peter May's user avatar
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9 votes
Accepted

Sign in May’s General algebraic approach to Steenrod operations

@FKranhold You mean I got it right? You had me fooled. I should apologize for leaving that detail to the reader, but let me give two excuses. First, one does not actually need that detail to prove L …
Peter May's user avatar
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7 votes
Accepted

Postnikov tower for $S^2$

I have no idea what source you are quoting, but you are quite right that it is wrong, unless we are both screwing up. One builds $\phi_n$ rigorously by inducting on the stages of the construction of …
Peter May's user avatar
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6 votes

Reading list for Equivariant Cohomology

I would like to point out that the term "equivariant cohomology'' is ambiguous. To those unfamiliar with modern algebraic topology, it means Borel cohomology, the cohomology theory that is the subjec …
Peter May's user avatar
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19 votes
Accepted

Homotopy extension of $E_{\infty}$-spaces

This is probably belaboring the obvious, but just take seriously the equivalence between grouplike $E_{\infty}$ spaces and connective spectra. See for example Equivalence between $E_\infty$-spaces …
Peter May's user avatar
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7 votes
Accepted

Homotopy of functors

I'm surprised this has been up for days with nobody telling Atticus the obvious. Let $I$ be the unit interval category with two objects, $0$ and $1$, and one non-identity arrow $0 \to 1$. A natural …
Peter May's user avatar
  • 30.4k
11 votes

How are characteristic classes morphisms of infinite loop spaces? (if they are)

Yes it is true. You have correctly interpreted the intended meaning of the phrase ``fibration of infinite loop spaces''. One early reference is chapter I of $E_{\infty}$ ring spaces and $E_{\infty}$ …
Peter May's user avatar
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4 votes
Accepted

Group completion of $E_k$-algebras

Group completion and the answer to your questions (for $k\geq 2$) are probaby best understood homologically. An ancient definition is that a map $X\rightarrow Y$ of homotopy commutative $H$-spaces …
Peter May's user avatar
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