Example 3.5.9.3. A morphism of Kan complexes $f: X \rightarrow Y$ is $(-1)$-truncated if and only if it induces a homotopy equivalence from $X$ to a summand of $Y$.
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Example 3.5.9.3. A morphism of Kan complexes $f: X \rightarrow Y$ is $(-1)$-truncated if and only if it induces a homotopy equivalence from $X$ to a summand of $Y$.