reserve X for non empty CUNITSTR;
reserve a, b for Complex;
reserve x, y for Point of X;
reserve X for ComplexUnitarySpace;
reserve x, y, z, u, v for Point of X;

theorem Th18:
  (-x).|.y = - x.|.y
proof
  (-x) .|. y = ((-1r)*x) .|. y by CLVECT_1:3
    .= (-1) * x .|. y by Def11,COMPLEX1:def 4;
  hence thesis;
end;
