theorem Th13:
  {VERUM(Al)} is Consistent
proof

set A =the  non empty set,J =the  interpretation of Al,A ,v =the  Element of
Valuations_in(Al,A);
  J,v |= VERUM(Al) by VALUAT_1:32;
  then for p st p in {VERUM(Al)} holds J,v |= p by TARSKI:def 1;
  then J,v |= {VERUM(Al)} by CALCUL_1:def 11;
  hence thesis by Th12;
end;
