Example 14.5.5. Suppose that X\to Y is a morphism of C such that all the pushouts Y\amalg _ X Y \amalg _ X \ldots \amalg _ X Y exist. Then we set U_ n equal to the (n + 1)-fold pushout, and we let \varphi : [n] \to [m] correspond to the map
on “coordinates”. In other words, the map U_1 = Y \amalg _ X Y \to U_0 = Y is the identity on each component. The two maps U_0 = Y \to U_1 = Y \amalg _ X Y are the two coprojections.
Comments (0)
There are also: