theorem Th9:
  C meets RightComp Cage (C,n)
proof
  N-min C in C & N-min C in RightComp Cage(C,n) by Th8,SPRECT_1:11;
  then C /\ RightComp Cage (C,n) <> {} by XBOOLE_0:def 4;
  hence thesis;
end;
