theorem
  for D being set, p,q be Element of D^omega holds FlattenSeq <% p,q %> = p ^ q
proof
  let D be set, p,q be Element of D^omega;
  consider g being BinOp of D^omega such that
A1: for d1,d2 being Element of D^omega holds g.(d1,d2) = d1^d2 and
A2: FlattenSeq <% p,q %> = g "**" <% p,q %> by Def10;
  thus FlattenSeq <% p,q %> = g.(p,q) by A2,Th38
    .= p ^ q by A1;
end;
