Displaying similar documents to “On Whitehead's inequality, nil [ X , G ] ≤ cat X .”

Category with a natural cone

Francisco Díaz, Sergio Rodríguez-Machín (2006)

Open Mathematics

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Generally, in homotopy theory a cylinder object (or, its dual, a path object) is used to define homotopy between morphisms, and a cone object is used to build exact sequences of homotopy groups. Here, an axiomatic theory based on a cone functor is given. Suspension objects are associated to based objects and cofibrations, obtaining homotopy groups referred to an object and relative to a cofibration, respectively. Exact sequences of these groups are built. Algebraic and particular examples...

Fibrations in the Category of Absolute Neighborhood Retracts

Takahisa Miyata (2007)

Bulletin of the Polish Academy of Sciences. Mathematics

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The category Top of topological spaces and continuous maps has the structures of a fibration category and a cofibration category in the sense of Baues, where fibration = Hurewicz fibration, cofibration = the usual cofibration, and weak equivalence = homotopy equivalence. Concentrating on fibrations, we consider the problem: given a full subcategory 𝓒 of Top, is the fibration structure of Top restricted to 𝓒 a fibration category? In this paper we take the special case where 𝓒 is the...

Cochains and homotopy type

Michael A. Mandell (2006)

Publications Mathématiques de l'IHÉS

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Finite type nilpotent spaces are weakly equivalent if and only if their singular cochains are quasi-isomorphic as E algebras. The cochain functor from the homotopy category of finite type nilpotent spaces to the homotopy category of E algebras is faithful but not full.