reserve T for non empty TopSpace,
  a, b, c, d for Point of T;
reserve X for non empty pathwise_connected TopSpace,
  a1, b1, c1, d1 for Point of X;

theorem
  for P being Path of a1, b1, Q being constant Path of a1, a1 holds P +
  - P, Q are_homotopic by Th84,BORSUK_2:def 3;
