theorem
  f in L1_CFunctions M & g in L1_CFunctions M implies (a.e-Ceq-class(f,M) =
  a.e-Ceq-class(g,M) iff g in a.e-Ceq-class(f,M))
proof
  assume
A1: f in L1_CFunctions M & g in L1_CFunctions M;
  then g a.e.cpfunc= f,M iff g in a.e-Ceq-class(f,M) by Th30;
  hence thesis by A1,Th32;
end;
