 reserve f,g for Function;
 reserve R for non empty reflexive RelStr;
 reserve R for non empty RelStr;
 reserve f for Function of the carrier of R, bool the carrier of R;

theorem :: k)
  for x,y being Subset of R holds
    ((Flip f_1 R).x \/ (Flip f_1 R).y) c= (Flip f_1 R).(x \/ y) by Propk;
