:: deftheorem defines (-) VALUED_2:def 34 :
for X being complex-functions-membered set
for Y being set
for f being PartFunc of X,Y
for b₄ being Function holds
( b₄ = f (-) iff ( dom b₄ = dom f & ( for x being complex-valued Function st x in dom b₄ holds
b₄ . x = f . (- x) ) ) );