reserve N,M,K for ExtNat;
reserve X for ext-natural-membered set;

theorem Th9:
  for p being non empty trivial Sequence
  ex x being object st p = <% x %>
proof
  let p be non empty trivial XFinSequence;
  consider x being object such that
    A1: rng p = {x} by ZFMISC_1:131;
  take x;
  consider z being object such that
    A2: dom p = {z} by ZFMISC_1:131;
  dom p = card {z} by A2;
  then A3: dom p = 1 by CARD_1:30;
  p = (dom p) --> x by A1, FUNCOP_1:9
    .= 0 .--> x by A3, CARD_1:49, FUNCOP_1:def 9;
  hence thesis by AFINSQ_1:def 1;
end;
