reserve a,b,c,d,m,x,n,j,k,l for Nat,
  t,u,v,z for Integer,
  f,F for FinSequence of NAT;
reserve p,q,r,s for real number;
reserve a,b,c,d,m,x,n,k,l for Nat,
  t,z for Integer,
  f,F,G for FinSequence of REAL;
reserve q,r,s for real number;
reserve D for set;

theorem
  f is FinSequence of D implies
    f|n is FinSequence of D & f/^n is FinSequence of D
  proof
    assume
    A1: f is FinSequence of D;
    (f|n)^(f/^n) = f by RFINSEQ:8;
    hence thesis by A1,FINSEQ_1:36;
  end;
