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

theorem Th39:
  for A,B being Subset of FT st FT is symmetric & A
is_a_component_of FT & B is_a_component_of FT holds A = B or A,B are_separated
proof
  let A,B be Subset of FT;
  assume that
A1: FT is symmetric and
A2: A is_a_component_of FT and
A3: B is_a_component_of FT;
A4: A is connected by A2;
  assume that
A5: A <> B and
A6: not A,B are_separated;
  B is connected by A3;
  then A \/ B is connected by A1,A6,A4,Th33;
  then B c= A \/ B & A = A \/ B by A2,XBOOLE_1:7;
  hence contradiction by A3,A5,A4;
end;
