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;
( [D,P1,P2] `1_3 = D & [D,P1,P2] `2_3 = P1 ) ;
then D = [|F1,F2|] by A1, A2, A3, Def22;
then reconsider P1 = P1 as Functor of [|F1,F2|],C1 ;
P1 = the pullback of F1,F2 `2_3 by A3;
hence the pullback of F1,F2 `2_3 is Functor of [|F1,F2|],C1 ; :: thesis: verum