set T = the pullback of F1,F2;

consider D being strict category, P1 being Functor of D,C1, P2 being Functor of D,C2 such that

A3: ( the pullback of F1,F2 = [D,P1,P2] & P1 is covariant & P2 is covariant & D,P1,P2 is_pullback_of F1,F2 ) by A1, A2, Def21;

thus the pullback of F1,F2 `1_3 is strict category by A3; :: thesis: verum

consider D being strict category, P1 being Functor of D,C1, P2 being Functor of D,C2 such that

A3: ( the pullback of F1,F2 = [D,P1,P2] & P1 is covariant & P2 is covariant & D,P1,P2 is_pullback_of F1,F2 ) by A1, A2, Def21;

thus the pullback of F1,F2 `1_3 is strict category by A3; :: thesis: verum