let U1, U2 be Universal_Algebra; for h being Function of U1,U2 st h is_isomorphism U1,U2 holds
MSAlg h is_isomorphism MSAlg U1,(MSAlg U2) Over (MSSign U1)
let h be Function of U1,U2; ( h is_isomorphism U1,U2 implies MSAlg h is_isomorphism MSAlg U1,(MSAlg U2) Over (MSSign U1) )
set A = (MSAlg U2) Over (MSSign U1);
set f = MSAlg h;
assume A1:
h is_isomorphism U1,U2
; MSAlg h is_isomorphism MSAlg U1,(MSAlg U2) Over (MSSign U1)
then
h is_epimorphism U1,U2
by ALG_1:def 4;
hence
MSAlg h is_epimorphism MSAlg U1,(MSAlg U2) Over (MSSign U1)
by Th18; MSUALG_3:def 10 MSAlg h is_monomorphism MSAlg U1,(MSAlg U2) Over (MSSign U1)
h is_monomorphism U1,U2
by A1, ALG_1:def 4;
hence
MSAlg h is_monomorphism MSAlg U1,(MSAlg U2) Over (MSSign U1)
by Th19; verum