reserve i,j,k,l for natural Number;
reserve A for set, a,b,x,x1,x2,x3 for object;
reserve D,D9,E for non empty set;
reserve d,d1,d2,d3 for Element of D;
reserve d9,d19,d29,d39 for Element of D9;
reserve p,q,r for FinSequence;

theorem
  for p being FinSequence of D holds p is Function of dom p, D
proof
  let p be FinSequence of D;
  rng p c= D by FINSEQ_1:def 4;
  hence thesis by FUNCT_2:2;
end;
