reserve FT for non empty RelStr,
  A,B,C for Subset of FT;

theorem Th35:
  for C being Subset of FT st FT is filled symmetric & C is
  connected holds C^b is connected
proof
  let C be Subset of FT;
  assume that
A1: FT is filled symmetric and
A2: C is connected;
  C c= C^b by A1,FIN_TOPO:13;
  hence thesis by A1,A2,Th34;
end;
