reserve V for set;

theorem Th22:
  for M being PseudoMetricSpace, V,Q being Element of M-neighbour,
  v being Element of REAL st V,Q is_dst v holds Q,V is_dst v
proof
  let M be PseudoMetricSpace, V,Q be Element of M-neighbour, v be Element of
  REAL;
  assume V,Q is_dst v;
  then for q,p being Element of M st q in Q & p in V holds dist(q,p)=v;
  hence thesis;
end;
