theorem Th13:
  EMF(C) c= f
proof
  let x be Element of C;
A1: rng f c= [.0,jj.] by RELAT_1:def 19;
  dom f = C & (EMF(C)).x = 0 by FUNCT_2:def 1,FUNCT_3:def 3;
  hence thesis by A1,Th12;
end;
