
theorem
  for D being set, p,q be Element of D* holds FlattenSeq <* p,q *> = p ^ q
proof
  let D be set, p,q be Element of D*;
  consider g being BinOp of D* such that
A1: for d1,d2 being Element of D* holds g.(d1,d2) = d1^d2 and
A2: FlattenSeq <* p,q *> = g "**" <* p,q *> by Def1;
  thus FlattenSeq <* p,q *> = g.(p,q) by A2,FINSOP_1:12
    .= p ^ q by A1;
end;
