theorem :: VFUNCT_1:37

for C being non empty set
for c being Element of C
for V being RealNormSpace
for f1, f2 being PartFunc of C,V st f1 is total & f2 is total holds
( (f1 + f2) /. c = (f1 /. c) + (f2 /. c) & (f1 - f2) /. c = (f1 /. c) - (f2 /. c) )