摘要: A closed curve in the plane is weakly simple if it limit (in Frechet metric) of a sequence curves. We describe an algorithm to determine whether walk length n graph O(n log n) time, improving earlier O(n3)-time Cortese et al. [Discrete Math. 2009]. As immediate corollary, we obtain first efficient arbitrary n-vertex polygon simple; our runs O(n2 time. also algorithms that detect weak simplicity time for two interesting classes polygons. Finally, discuss subtle errors several previously published definitions simplicity.