Algebraic Topology: Homotopy and Homology
《Algebraic Topology: Homotopy and Homology》 · 第 37 页 · Definition 3.7
If \(A\subset X\) is a retract with retraction \(r\) and the homotopy \(ir\simeq\operatorname{id}_X\) is relative to \(A\), then \(A\) is called a strong deformation retract of \(X\).