
theorem Th9:
  for L being non empty 1-sorted, N being net of L, p being
  Function of N,N holds N * p is net of L
proof
  let L be non empty 1-sorted, N be net of L, p be Function of N,N;
  N * p = NetStr(#the carrier of N,the InternalRel of N,(the mapping of N
    ) * p #) by Th7;
  hence thesis;
end;
