
theorem Th1:
  for D being set, d be Element of D* holds FlattenSeq <*d*> = d
proof
  let D be set, d be Element of D*;
  ex g being BinOp of D* st
  (for p, q being Element of D* holds g.(p,q) = p^q) &
  FlattenSeq <*d*> = g "**" <* d *> by Def1;
  hence thesis by FINSOP_1:11;
end;
