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 D being set, D9 being FinSequenceSet of D holds D9 c= D*
proof
  let D be set, D9 be FinSequenceSet of D;
  let a be object;
  assume a in D9;
  then a is FinSequence of D by Def3;
  hence thesis by FINSEQ_1:def 11;
end;
