reserve p,q,r for FinSequence,
  x,y for object;

theorem Th10:
  for R,Q being Relation st R c= Q for p being RedSequence of R
  holds p is RedSequence of Q
proof
  let R,Q be Relation such that
A1: R c= Q;
  let p be RedSequence of R;
  thus len p > 0;
  let i be Nat;
  assume i in dom p & i+1 in dom p;
  then [p.i, p.(i+1)] in R by Def2;
  hence thesis by A1;
end;
