generated at
余直積

a,b \in \operatorname{Obj}(C)の余直積をa \amalg bと書く

余直積は余極限
a \amalg b = \operatorname{colim}T
J \coloneqq \{1,\ 2\}
T\colon J \to C
whereT(1)=a, \ T(2)=b