The composition of binary relations R_1 and R_2 is a relation R_3 such that R_1(x,y) and R_2(y,z) implies R_3(x,z).
(Nth-Domain Composition 3 Binary-Relation) (Nth-Domain Composition 2 Binary-Relation) (Nth-Domain Composition 1 Binary-Relation) (=> (Composition ?R1 ?R2 ?R3) (And (Binary-Relation ?R1) (Binary-Relation ?R2) (= ?R3 (Setofall (Listof ?X ?Z) (Exists (?Y) (And (Holds ?R1 ?X ?Y) (Holds ?R2 ?Y ?Z)))))))