Question 3.2.0.1. Let $f: X \rightarrow Y$ be a morphism of Kan complexes. Under what conditions does $f$ admit a homotopy inverse $g: Y \rightarrow X$?
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Question 3.2.0.1. Let $f: X \rightarrow Y$ be a morphism of Kan complexes. Under what conditions does $f$ admit a homotopy inverse $g: Y \rightarrow X$?