
theorem Th1:
  for L be sup-Semilattice for x,y be Element of L holds "/\"((
  uparrow x) /\ (uparrow y),L) = x "\/" y
proof
  let L be sup-Semilattice;
  let x,y be Element of L;
  (uparrow x) /\ (uparrow y) = uparrow (x "\/" y) by WAYBEL14:4;
  hence thesis by WAYBEL_0:39;
end;
