
theorem Th4:
  for S being non empty non void identifying_close_blocks TopStruct
  holds S is strongly_connected implies S is connected
proof
  let S being non empty non void identifying_close_blocks TopStruct;
  assume
A1: S is strongly_connected;
  then S is without_isolated_points by Th3;
  hence thesis by A1,PENCIL_1:28;
end;
