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

theorem
  a\(a"\/"b) = Bottom L
proof
  thus a\(a"\/"b) = a"/\"('not' a"/\"'not' b) by Th36
    .= (a"/\"'not' a)"/\"'not' b by LATTICE3:16
    .= Bottom L"/\"'not' b by Th34
    .= Bottom L by WAYBEL_1:3;
end;
