1981年，L．Block发现在一维自映射中，Sarkovskii定理对映射的扰动而言是稳定的；文[1]针对一类可降的n维自映射，证明了其扰动也是稳定的；本......

Let and f:Xn→Xn be a continuous map. If f is a second descendible map, then P(f) is closed if and only if one of the fo......