reserve
  a for natural Number,
  k,l,m,n,k1,b,c,i for Nat,
  x,y,z,y1,y2 for object,
  X,Y for set,
  f,g for Function;
reserve p,q,r,s,t for FinSequence;
reserve D for set;

theorem
  for D being set, p,q being D-valued FinSequence holds p^q is FinSequence of D
  proof
    let D be set, p,q be D-valued FinSequence;
    reconsider p,q as FinSequence of D by LL;
    p^q is FinSequence of D;
    hence thesis;
  end;
