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La classe des morphismes de Dwyer n'est pas stable par rétractes

1999; Volume: 40; Issue: 3 Linguagem: Inglês

1245-530X

Denis-Charles Cisinski,

Advanced Topology and Set Theory

In [1] R. Thomason claims that a retract of a Dwyer map is a Dwyer map to show the closed model category structure he defined on the category of small categories is proper. This paper gives a counterexample to this claim and shows how to give a proof of the propriety axiom.