:: deftheorem Def1 defines Re COMPLEX1:def 1 :
for z being Complex
for b₂ being number holds
( ( z is real implies ( b₂ = Re z iff b₂ = z ) ) & ( not z is real implies ( b₂ = Re z iff ex f being Function of 2,REAL st
( z = f & b₂ = f . 0 ) ) ) );