theorem Th27:
  not (ex S st S is Sub_atomic Sub_negative or S is Sub_atomic
  Sub_conjunctive or S is Sub_atomic Sub_universal or S is Sub_negative
  Sub_conjunctive or S is Sub_negative Sub_universal or S is Sub_conjunctive
Sub_universal or S is A-Sub_VERUM Sub_atomic or S is A-Sub_VERUM
Sub_negative or S
  is A-Sub_VERUM Sub_conjunctive or S is A-Sub_VERUM Sub_universal )
proof
  let S;
A1: S is Sub_negative implies ((@S`1).1)`1 = 1 by Th25;
A2: S is Sub_conjunctive implies ((@S`1).1)`1 = 2 by Th25;
A3: S is Sub_universal implies ((@S`1).1)`1 = 3 by Th25;
  S is A-Sub_VERUM implies ((@S`1).1)`1 = 0;
  hence thesis by A1,A2,A3,Th26;
end;
