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6 votes

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

Here is something that I think is reasonably difficult to get around. As you observe, the unit is the initial object of commutative monoids, and so your request includes that the unit is cofibrant. ...
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24 votes
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What happened to the last work Gaunce Lewis was doing when he died?

Lewis wrote, but never published, a very influential paper setting foundations for the multiplicative theory for Mackey functors. The paper is called "The Theory of Green functors" and Doug ...
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9 votes
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Does a Gysin map depend on the choice of Thom class?

Yes it does! The map in your display is (more or less) the cup product with the Thom class $\lambda_N$. So if you choose a different Thom class you'll get a different map. For example, take the ...
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3 votes

"Phantom" non-equivalences of spectra?

Here's a connective example. It is also an example of Maxime's variant question in the comments (regarding $\tau_{\leq m}$ truncations). And thanks to Maxime for looking this argument over before I ...
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14 votes
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"Phantom" non-equivalences of spectra?

For this we can use a swindle-type technique. Let $B = \bigoplus_{n=2}^\infty H\Bbb Z/2$, and $A = \bigoplus_{n=2}^\infty \Sigma^{-n} H\Bbb Z/2$. We can construct maps $A \to B$ by specifying their ...
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