
theorem :: 4.21
  for L being join-commutative join-associative Huntington non empty
  ComplLLattStr, a being Element of L holds a *' a = a
proof
  let L be join-commutative join-associative Huntington non empty
  ComplLLattStr, a be Element of L;
  thus a *' a = a`` by Def7
    .= a by Th3;
end;
