reserve L for Boolean non empty RelStr;
reserve a,b,c,d for Element of L;

theorem
  a"/\"b misses a\b
proof
  (a"/\"b)"/\"(a\b) = ((a"/\"b)"/\"'not' b)"/\"a by LATTICE3:16
    .= (a"/\"(b"/\"'not' b))"/\"a by LATTICE3:16
    .= (a"/\"Bottom L)"/\"a by Th34
    .= Bottom L"/\"a by WAYBEL_1:3
    .= Bottom L by WAYBEL_1:3;
  hence thesis;
end;
