Hopf-Algebra/Assoziativität/Diagramm

${\begin{matrix}H&{\stackrel {\Delta }{\longrightarrow }}&H\otimes _{K}H&\\\!\!\!\!\!\!\!\Delta \downarrow &&\downarrow \operatorname {Id} _{H}\otimes \Delta \!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!&\\H\otimes _{K}H&{\stackrel {\Delta \otimes \operatorname {Id} _{H}}{\longrightarrow }}&H\otimes _{K}H\otimes _{K}H&\!\!\!\!\!\\\end{matrix}}$