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In mathematics, in particular in homotopy theory within algebraic topology, the homotopy lifting property (also known as an instance of the right lifting property or the covering homotopy axiom) is a technical condition on a continuous function from a topological space E to another one, B.
In mathematics, in particular in category theory, the lifting property is a property of a pair of morphisms in a category.It is used in homotopy theory within algebraic topology to define properties of morphisms starting from an explicitly given class of morphisms.
Given two topological spaces X and Y, a homotopy equivalence between X and Y is a pair of continuous maps f : X → Y and g : Y → X, such that g ∘ f is homotopic to the identity map id X and f ∘ g is homotopic to id Y. If such a pair exists, then X and Y are said to be homotopy equivalent, or of the same homotopy type.
Because fibrations satisfy the homotopy lifting property, and Δ is contractible; p −1 (Δ) is homotopy equivalent to F. So this partially defined section assigns an element of π n (F) to every (n + 1)-simplex. This is precisely the data of a π n (F)-valued simplicial cochain of degree n + 1 on B, i.e. an element of C n + 1 (B; π n (F)).
In what follows, let = [,] denote the unit interval.. A map : of topological spaces is called a cofibration [1] pg 51 if for any map : such that there is an extension to (meaning: there is a map ′: such that ′ =), we can extend a homotopy of maps : to a homotopy of maps ′:, where
This follows from the Homotopy lifting property. The projection of the letter L onto its base interval is a quasifibration, but not a fibration. More generally, the projection M f → I of the mapping cylinder of a map f : X → Y between connected CW complexes onto the unit interval is a quasifibration if and only if π i ( M f , p −1 ( b ...
In topology, a fibration is a mapping : that has certain homotopy-theoretic properties in common with fiber bundles. Specifically, under mild technical assumptions a fiber bundle always has the homotopy lifting property or homotopy covering property (see Steenrod (1951, 11.7) for details). This is the defining property of a fibration.
These homotopy classes form a group, called the n-th homotopy group, (), of the given space X with base point. Topological spaces with differing homotopy groups are never homeomorphic , but topological spaces that are not homeomorphic can have the same homotopy groups.