Cofibration
In mathematics, in particular homotopy theory, a continuous mapping
where A and X are topological spaces, is a cofibration if it satisfies the homotopy extension property with respect to all spaces Y. This definition is dual to that of a fibration, which is required to satisfy the homotopy lifting property with respect to all spaces. This duality is informally referred to as Eckmann–Hilton duality.
A more general notion of cofibration is developed in the theory of model categories.
The homotopy colimit generalizes the notion of a cofibration.
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