theorem Th11:
  A c= Union FNDSC(V,A)
  proof
    set F = FNDSC(V,A);
A1: A = F.0 by Def3;
    dom F = NAT by Def3;
    then F.0 in rng F by FUNCT_1:def 3;
    hence thesis by A1,ZFMISC_1:74;
  end;
