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

theorem Th22:
  for R,Q being Relation st R c= Q for a,b being object st
  R reduces a,b holds Q reduces a,b
proof
  let R,Q be Relation such that
A1: R c= Q;
  let a,b be object;
  given p being RedSequence of R such that
A2: p.1 = a & p.len p = b;
  p is RedSequence of Q by A1,Th10;
  hence ex p being RedSequence of Q st p.1 = a & p.len p = b by A2;
end;
