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A model category is a category equipped with notions of weak equivalences, fibrations and cofibrations allowing to run arguments similar to those of classical homotopy theory.

15 votes
2 answers
1k views

"Strøm-type" model structure on chain complexes?

Background The Quillen model structure on spaces has weak equivalences given by the weak homotopy equivalences and the fibrations are the Serre fibrations. The cofibrations are characterized by t …
John Klein's user avatar
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4 votes
1 answer
415 views

Alternative model structure on retractive spaces

Background For a topological space $X$, let $R(X)$ be the category of retractive spaces over $X$. An object of this category is a space $Y$ equipped with maps $s: X \to Y$ and $r: Y \to X$ such that …
John Klein's user avatar
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6 votes

Homotopy fibre of composition

$\require{AMScd}$ Here are some details. Without loss in generality, we can assume $f$ and $g$ are fibrations. I am assuming that all spaces are based. We may assume that $F_f$ now refers to the actua …
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2 votes
Accepted

Model categories and cellular maps

The answer to your question is yes in the case of cellular maps of topological spaces. (I think a similar argument works in the simplicial case, but I doubt the result is true in the CW case.) There …
John Klein's user avatar
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8 votes

Homotopic maps out of cofibration sequences

I once read in a paper of McGibbon about the following example: Let $X = \Bbb RP^\infty$ and let $X_n$ be the $n$-skeleton. Then there is a canonical map $\vee_n X_n \to X$. The mapping cone of thi …
John Klein's user avatar
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7 votes

Why does this construction give a (homotopy-invariant) suspension (resp. homotopy cofiber) i...

An argument showing that the two models of suspension are equivalent will probably be based on something like the following: Assertion: Suppose we are given a commutative diagram of the form $\requir …
John Klein's user avatar
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4 votes
1 answer
176 views

Equivariant versus retractive spaces: a reference request

Let $T$ be the category of compactly generated weak Hausdorff spaces with model structure given by Serre fibrations, Serre cofibrations and weak homotopy equivalences. Let $G = |G.|$ be the (geometric …
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1 vote

Existence of homotopy limits and colimits in model categories

Edit: The questioner has objected to the fact that the reference I gave to Q1 assumes functoriality. Here is another reference which doesn't: https://pages.uoregon.edu/ddugger/hocolim.pdf See es …
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19 votes

Fibrations and Cofibrations of spectra are "the same"

The following might help answer the last part of your post: In the late 1960s, Tudor Ganea developed technology that studies the difference between the homotopy fibers and cofibers of a map. For exam …
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