:: deftheorem Def1 defines (#) VFUNCT_2:def 1 :
for M being non empty set
for V being ComplexNormSpace
for f1 being PartFunc of M,COMPLEX
for f2, b₅ being PartFunc of M,V holds
( b₅ = f1 (#) f2 iff ( dom b₅ = (dom f1) /\ (dom f2) & ( for c being Element of M st c in dom b₅ holds
b₅ /. c = (f1 /. c) * (f2 /. c) ) ) );