let B, C, D be Category; :: thesis: for S1 being Contravariant_Functor of C,B
for S2 being Functor of B,D holds S2 * S1 is Contravariant_Functor of C,D
let S1 be Contravariant_Functor of C,B; :: thesis: for S2 being Functor of B,D holds S2 * S1 is Contravariant_Functor of C,D
let S2 be Functor of B,D; :: thesis: S2 * S1 is Contravariant_Functor of C,D
*' S1 is Functor of C opp ,B by Th53;
then S2 * (*' S1) is Functor of C opp ,D by CAT_1:73;
then /* (S2 * (*' S1)) is Contravariant_Functor of C,D by Th32;
then S2 * (/* (*' S1)) is Contravariant_Functor of C,D by Lm18;
hence S2 * S1 is Contravariant_Functor of C,D by Th45; :: thesis: verum