ex F being Function st
( dom F = (dom f) /\ (dom g) & ( for x being object st x in (dom f) /\ (dom g) holds
F . x = H₁(x) ) ) from FUNCT_1:sch 3();
hence ex b₁ being Function st
( dom b₁ = (dom f) /\ (dom g) & ( for x being object st x in dom b₁ holds
b₁ . x = (f . x) /" (g . x) ) ) ; :: thesis: verum