Definition 3.2.4.1. Let $X$ be a simplicial set. We say that $X$ is contractible if the projection map $X \rightarrow \Delta ^0$ is a homotopy equivalence (Definition 3.1.6.1).
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Definition 3.2.4.1. Let $X$ be a simplicial set. We say that $X$ is contractible if the projection map $X \rightarrow \Delta ^0$ is a homotopy equivalence (Definition 3.1.6.1).