reserve S, T, Y for non empty TopSpace,
  s, s1, s2, s3 for Point of S,
  t, t1, t2, t3 for Point of T,
  l1, l2 for Path of [s1,t1],[s2,t2],
  H for Homotopy of l1 ,l2;

theorem Th30:
  pi_1([:S,T:],[s,t]), product <*pi_1(S,s),pi_1(T,t)*> are_isomorphic
proof
  take FGPrIso(s,t);
  thus thesis;
end;
