reserve X,x for set;

theorem Th3:
 for x being object holds  <*x*> is FinSequence of X implies x in X
proof let x be object;
A1: rng<*x*> = {x} by FINSEQ_1:38;
  assume <*x*> is FinSequence of X;
  then {x} c= X by A1,FINSEQ_1:def 4;
  hence thesis by ZFMISC_1:31;
end;
