约瑟夫环是一个数学的应用问题：已知n个人（以编号1，2，3...n分别表示）围坐在一张圆桌周围。从编号为k的人开始报数，数到m的那个人出列；他的下一个人又从1开始报数，数到m的那个人又出列；依此规律重复下去，直到圆桌周围的人全部出列。

-Josephus is the application of a mathematical problem: Given n individuals (numbered 1, 2, 3 ... n, respectively) sitting around a round table. People began to number off from the number k, the number m of that person out of the line　his next and from one number off, count to m, the man was out of the line　so regularly repeated down until the round table around were all out of the line.