
theorem
  for x,y being set holds {x,y,x \/ y} is c=directed
proof
  let x,y be set;
  set X = {x,y,x \/ y};
  let A be finite Subset of X;
  take a = x \/ y;
  union X = a by Lm2;
  hence union A c= a by ZFMISC_1:77;
  thus thesis by ENUMSET1:def 1;
end;
