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Homotopy theory, homological algebra, algebraic treatments of manifolds.

2 votes

Looking for examples of maps $\Omega^lS^{n+l}\to\Omega^kS^{m+k}$ with $l>k$

Localize at a prime $p$. Then (this is from my comment above) there is a fiber sequence $$J_{p^k−1}S^{2n} \to \Omega S^{2n+1} \to \Omega S^{2npk+1},$$ coming from the combinatorial James-Hopf map (see …
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6 votes
0 answers
184 views

The chromatic splitting conjecture and functoriality

Let $M$ be a finite spectrum, so that $L_{K(n)} M = M \wedge L_{K(n)} S$. Recall that (a weak version of) the chromatic splitting conjecture states that the chromatic attaching map $L_{n-1} M \to L_{n …
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2 votes

To compare the total, base and fiber spaces of two fiber bundles

Let $f$ be the map between the two Serre fibrations. The question then asks: if $f$ is a rational homotopy equivalence on the base and total spaces, then is it a rational homotopy equivalence on the f …
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9 votes
Accepted

Lecture notes by Mahowald and Unell

I scanned the notes (apologies for the delay). Thanks a lot to Peter May for lending me the notes and for letting me scan them! Here's the link: http://www.mit.edu/~sanathd/mahowald-unell-bott.pdf.
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11 votes
1 answer
408 views

Finite complexes which are not Thom spectra

I'll be working in the stable world. It's an easy observation that any 2-cell complex (over the sphere) with bottom cell in dimension zero is a Thom spectrum: any such complex is the cofiber of some e …
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6 votes
Accepted

Is the mod-2 Moore spectrum a retract of a shift of its tensor square?

The mod $2$ cohomology of $S^0/2 \wedge S^0/2$ is a $\mathbf{F}_2$-vector space on generators in degrees 0, 1, 1, and 2. The classes in degrees 0 and 2 are connected by a nontrivial $\mathrm{Sq}^2$, s …
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9 votes
3 answers
734 views

Lecture notes by Mahowald and Unell

I'm trying to find lecture notes of Mahowald and Unell, titled "Lectures on Bott periodicity in stable and unstable homotopy at the prime 2". Does anyone happen to know if a copy exists online (and if …
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2 votes

Crafting Suspension Spectra

For large $i_0,\cdots,i_n$ we can realize $BP_\ast/(v_0^{i_0},\cdots,v_n^{i_n})$ as the $BP$-homology of a finite spectrum $S/(v_0^{i_0},\cdots,v_n^{i_n})$. This follows from Devinatz-Hopkins-Smith. S …
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8 votes
Accepted

The connective $k$-theory cohomology of Eilenberg-MacLane spectra

Charles Rezk already answered this in the comments; I'll just expand on what he wrote. This paper discusses what's now known as Mahowald-Rezk duality; this is a version of Anderson duality that takes …
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17 votes
Accepted

Homology of spectra vs homology of infinite loop spaces

$\newcommand{\H}{\mathrm{H}} \newcommand{\Z}{\mathbf{Z}}$Let $X$ be a space. Then the $E$-(co)homology of $X$ is the same as the $E$-(co)homology of its suspension spectrum, i.e., $E_\ast(X) \cong E_\ …
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6 votes
1 answer
491 views

Unstable Greek letter elements

A theorem of Hopkins and Mahowald states that the Thom spectrum of the map $\Omega^2 S^3 \to B\mathrm{GL}_1(\mathbb{S}_{(p)})$ classifying the element $p$ is exactly $\mathrm{H}\mathbf{F}_p$. Let $T(1 …
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2 votes
Accepted

Mapping a loop space to quaternionic projective space

[I should've posted this answer a long time ago, given that it was answered in the comments.] In order to extend the map $S^4\to \mathbf{H}P^\infty$ to a map from $J_2(S^4)$, the composite of $[\iota_ …
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11 votes
0 answers
432 views

$E_\infty\mathrm{Spaces}(\mathbf{Z}/p\mathbf{Z},GL_1(E_n))$ and Eilenberg-Maclane spaces

$\newcommand{\Z}{\mathbf{Z}}$Let $p$ be a prime. In his answer here, Jacob Lurie conjectured that $E_\infty\mathrm{Spaces}(\mathbf{Z}/p\mathbf{Z},GL_1(E_n))\simeq K(\Z/p\Z,n)$ where $E_n$ denotes the …
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16 votes
Accepted

The structure of complex cobordism cohomology of the Eilenberg-Maclane spectrum

One can prove that $\mathrm{Map}(H\mathbf{F}_p,MU)$ is contractible. We know that $H\mathbf{F}_p$ is dissonant (Theorem 4.7 of Ravenel's "Localization with Respect to Certain Periodic Homology Theorie …
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2 votes
Accepted

Homology of a loop-suspension space and action of $\mathcal{D}_1$-operad

$\newcommand{\E}{\mathbf{E}} \newcommand{\co}{\mathcal{O}} \newcommand{\free}{\mathrm{Free}} \newcommand{\H}{\mathrm{H}}$Here's one way of seeing the Bott-Samelson theorem. The James splitting gives a …
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