
theorem Th22: :: 4.26
  for L being join-commutative join-associative Huntington non
empty ComplLLattStr, a, b being Element of L
   st a` + b = Top L & b` + a = Top L
  holds a = b
proof
  let L be join-commutative join-associative Huntington non empty
  ComplLLattStr, a, b be Element of L;
  assume
A1: a` + b = Top L & b` + a = Top L;
  thus a = (a` + b`)` + (a` + b)` by Def6
    .= b by A1,Def6;
end;
