reserve Omega for set;
reserve X, Y, Z, p,x,y,z for set;
reserve D, E for Subset of Omega;
reserve f for Function;
reserve m,n for Nat;
reserve r,r1 for Real;
reserve seq for Real_Sequence;
reserve F for Field_Subset of X;

theorem
  { {} , X } c= F & F c= bool X
proof
  {} in F & X in F by Th4,Th5;
  then for x being object holds x in { {} , X } implies x in F
   by TARSKI:def 2;
  hence thesis;
end;
