
theorem Th17: :: 4.20
  for L being join-commutative join-associative Huntington non
  empty ComplLLattStr, a, b being Element of L holds a + b = (a` *' b`)`
proof
  let L be join-commutative join-associative Huntington non empty
  ComplLLattStr, a, b be Element of L;
  a` *' b` = (a`` + b)` by Th3
    .= (a + b)` by Th3;
  hence thesis by Th3;
end;
