theorem Th69:
  for F being Function of [:D,D9:],E for p being FinSequence of D
  for q being FinSequence of D9 st r = F.:(p,q) holds len r = min(len p,len q)
proof
  let F be Function of [:D,D9:],E;
  let p be FinSequence of D;
  let q be FinSequence of D9;
  rng p c= D & rng q c= D9 by FINSEQ_1:def 4;
  then [:rng p,rng q:] c= [:D,D9:] by ZFMISC_1:96;
  then [:rng p,rng q:] c= dom F by FUNCT_2:def 1;
  hence thesis by Th63;
end;
