 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 :: l)
  for x,y being Subset of R holds
    (f_0 R).(x /\ y) c= (f_0 R).x /\ (f_0 R).y by Propl;
