
theorem
  for L be antisymmetric transitive with_suprema with_infima RelStr for
  a,b,c being Element of L holds a"/\"b <= a"\/"c
proof
  let L be antisymmetric transitive with_suprema with_infima RelStr;
  let a,b,c be Element of L;
  a"/\"b <= a & a <= a"\/"c by YELLOW_0:22,23;
  hence thesis by YELLOW_0:def 2;
end;
