reserve n,m,i,j,k for Nat,
  x,y,e,X,V,U for set,
  W,f,g for Function;
reserve p,q for FinSequence;

theorem Th5:
  (for n,m st 1<=n & n<m & m<=len p holds p.n <> p.m) iff card rng p = len p
      by Th4,FINSEQ_4:62;
