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Stable homotopy theory is that part of homotopy theory (and thus algebraic topology) concerned with all structure and phenomena that remain after sufficiently many applications of the suspension functor.

9 votes
Accepted

Homology exponents for $QX$

By May's Remark 2.6, the answer should be no. If $X$ is a Moore space with $\tilde H_*(X; Z) = Z/p$ concentrated in an odd degree $2q-1$, and $\tilde H_*(X; Z/p) = Z/p\{x, y\}$ with $\beta_1(y) = x$, …
John Rognes's user avatar
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7 votes

Are these two notions of "dualizable" spectra equivalent?

Let $R$ be bounded below, bounded above and nontrivial, and work in $R$-modules. Let $X = \bigvee_{n\in\mathbb{Z}} \Sigma^n R$. Then $X \overset{\simeq}\to D(DX)$ is an equivalence, but $X$ is not d …
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4 votes
Accepted

When does a map in the stable homotopy group gets killed when smashed with cone of itself?

The answer to your third question is "yes". A little more generally, if $Sq^{n+1}$ acts nontrivially in the mod $2$ cohomology of $C$, then $Sq^{(k+1)(n+1)}$ acts nontrivially in the mod $2$ cohomolo …
John Rognes's user avatar
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19 votes
Accepted

Realizing $\mathcal{A}(2)//\mathcal{A}(1)$ by a finite spectrum

The $A(2)$-module structure on $A(2)//A(1)$ does not extend to an $A$-module structure. In particular, there is no spectrum $X$ with $H^*(X; F_2) = A(2)//A(1)$ as an $A(2)$-module. Additively, $A(2) …
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4 votes

Injectivity of assembly in A-theory for $BC_2 = \mathbb R P^\infty$ in degree $4$

Not an answer, but a possible approach: Using Dundas' cartesian square with corners $A(*)$, $K(Z)$, $TC(*)$ and $TC(Z)$ you can see that $Wh^{Diff}_3(*) = Z/2$ comes from $TC_4(Z) = Z/8$ (plus odd tor …
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8 votes
Accepted

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

For $3$-primary homotopy of $S$ there is early work by Nakamura, Osamu Some differentials in the mod 3 Adams spectral sequence. Bull. Sci. Engrg. Div. Univ. Ryukyus Math. Natur. Sci. No. 19 (1975), 1– …
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7 votes
Accepted

Generalization of Hopf invariant

The $E$-based Adams spectral sequence is the homotopy spectral sequence associated to the tower of spectra $\dots \to Y_2 \to Y_1 \to Y_0 = S$ with $Y_{s+1} \to Y_s \to E \wedge Y_s$ a homotopy fiber …
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7 votes

What are the naive fixed points of a non-naive smash product of a spectrum with itself?

In the context of functors with smash product (FSP), or symmetric spectra, or orthogonal spectra, the spectrum with $\Sigma_2$-action $X \wedge X$ prolongs essentially uniquely to a $\Sigma_2$-spectru …
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15 votes
0 answers
550 views

How well-defined is $\bar\kappa$ in the stable $20$-stem?

The $2$-completed stable $20$-stem $\pi_{20}(S)_2$ is cyclic of order $8$. Mimura and Toda (1963, Lemma 15.4) mr=157384 show the existence of a class $\bar\kappa_7 \in \pi_{27}(S^7)$ whose stable cla …
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7 votes

Splitting of $H\mathbb{Z}$-module spectra

Perhaps it helps to first think about how you can construct a map $\alpha_k : \Sigma^k S(\pi_k M) \to M$ inducing an isomorphism on $\pi_k$. Choose a free resolution $$ 0 \to \bigoplus_{j \in J} \mat …
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8 votes

Detection of stable homotopy by K-theory spectra

I would say that the historically correct place to start is Quillen's letter to Milnor on the image of $(\pi_i O \to \pi_i^s \to K_i\mathbb{Z})$, published in Springer LNM 551 (1976). There Quillen pr …
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2 votes

Anything between vector bundles and sphere bundles?

Just as $ku$ is quite close to $H\mathbb Z$ in the sequence $S \to ku \to H\mathbb Z$ of commutative ring spectra, and $KU$ is quite close to $H\mathbb Q$, the classifying space $BGL(ku)$ for $2$-vect …
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9 votes
Accepted

Explicit $BP_*BP$-comodule structure on $BP_*\mathbb{C}P^n$ and $BP_*\mathbb{C}P^{\infty}$

A concise formula $$ \mu(\beta) = \beta(c(t^F)) $$ for the $BP_* BP$-coaction $\mu$ on $BP_* CP^\infty$ is given in the "Note added in proof" on page 279 of Ravenel, Douglas C.; Wilson, W. Stephen The …
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17 votes

Differentials in the Adams Spectral Sequence for spheres at the prime p=2

With the aid of machine computations, you can readily determine the Adams differentials up to $t-s=30$ using the multiplicative structure, the relation between Steenrod operations in $\text{Ext}_A$ an …
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6 votes

Relation between cohomology operations and the Adams spectral sequence

Maybe these references can help: Mauder, C. R. F. On the differentials in the Adams spectral sequence. Proc. Cambridge Philos. Soc. 60 (1964), 409–420. Mosher, Robert E.; Tangora, Martin C. Cohomolo …
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