Simplicial mapping space
= Simplicial mapping space
{title2=$\underline{\operatorname{Hom}}(A,X)$}
The simplicial mapping space is defined by
$$
\underline{\operatorname{Hom}}(A,X)_n
=\operatorname{Hom}(A\times\Delta^n,X).
$$
If $A\hookrightarrow B$ is a monomorphism and $X$ is a <Kan complex>, restriction $\underline{\operatorname{Hom}}(B,X)\to\underline{\operatorname{Hom}}(A,X)$ is a Kan fibration.