A non-PI minimal system is Li-Yorke sensitive
  It is shown that any non-PI minimal system is Li-Yorke sensitive. Consequently, any minimal system with nontrivial weakly mixing factor (such a system is non-PI) is Li-Yorke sensitive, which answers affirmatively an open question by Akin and Kolyada. 
Song Shao and Xiangdong Ye
math.DS