reserve x,y,z,c for object,
  f for Function of 2-tuples_on BOOLEAN, BOOLEAN;

theorem Th59:
  for x,y,c being non pair object
   holds InputVertices 2GatesCircStr(x,y,c,f) is without_pairs
proof
  let x,y,c be non pair object;
  InputVertices 2GatesCircStr(x,y,c,f) = {x,y,c} by Th57;
  hence thesis;
end;
