theorem Th11:
  Union (X|`psi) is epsilon-transitive epsilon-connected set
proof
  consider A such that
A1: rng psi c= A by ORDINAL2:def 4;
A2: rng (X|`psi) c= rng psi by RELAT_1:87;
A3: now
    let x be object;
    assume x in rng (X|`psi);
    then x in A by A1,A2;
    hence x is Ordinal;
  end;
  Union (X|`psi) = union rng (X|`psi) by CARD_3:def 4;
  hence thesis by A3,ORDINAL1:23;
end;
