It provides the method of determining the k-periodic window for some discrete dynamic systems in chaos region by taking advantage of the critical point property.

Condition of the continuous self-mapping of unit solid body in R~n with prime periodic points;

Nitecki indicate the equal value of the special abnormal point,abnormal point and prime periodic point,respectively.

Nitecki indicates respectively the equalvalue of the spcial heterochinic,point,heterochinic point and prime periodic point.