let S be non empty non void ManySortedSign ; for U1 being strict non-empty MSAlgebra of S ex U0 being strict non-empty free MSAlgebra of S ex F being ManySortedFunction of U0,U1 st
( F is_epimorphism U0,U1 & Image F = U1 )
let U1 be strict non-empty MSAlgebra of S; ex U0 being strict non-empty free MSAlgebra of S ex F being ManySortedFunction of U0,U1 st
( F is_epimorphism U0,U1 & Image F = U1 )
consider U0 being strict non-empty free MSAlgebra of S, F being ManySortedFunction of U0,U1 such that
A1:
F is_epimorphism U0,U1
by Th19;
F is_homomorphism U0,U1
by A1, MSUALG_3:def 10;
then
Image F = U1
by A1, MSUALG_3:19;
hence
ex U0 being strict non-empty free MSAlgebra of S ex F being ManySortedFunction of U0,U1 st
( F is_epimorphism U0,U1 & Image F = U1 )
by A1; verum