reserve R for non empty RelStr,
  N for net of R,
  i for Element of N;

theorem Th26:
  for S being non empty 1-sorted, e being Element of S,
  x being Element of Net-Str e holds (Net-Str e).x = e
proof
  let S be non empty 1-sorted, e be Element of S, x be Element of Net-Str e;
  set N = Net-Str e;
A1: the carrier of Net-Str e = {e} by Def11;
  then
A2: x = e by TARSKI:def 1;
  thus N.x = (id{e}).x by Def11
    .= e by A1,A2;
end;
