
theorem
  for A being Universal_Algebra st Constants A = {}
  for G being GeneratorSet of A holds G <> {}
proof
  let A be Universal_Algebra such that
A1: Constants A = {};
  let G be GeneratorSet of A;
  assume
A2: G = {};
  then G = {} A;
  then G is opers_closed by A1,Th28;
  hence thesis by A2,FREEALG:def 4;
end;
