theorem Th47:
  for A being Cell of k,G, B being Cell of (k + 1),G holds
  B in star A iff A c= B
proof
  let A be Cell of k,G, B be Cell of (k + 1),G;
  defpred P[set] means A c= $1;
A1: star A = { B9 where B9 is Cell of (k + 1),G : P[B9] };
  thus B in star A iff P[B] from LMOD_7:sch 7(A1);
end;
