The solution regards the original given interface ( original curve or interface ) as one zero set of function , transferring the some phenomena such as topology to lever set function in higher dimension , and getting moving interface of original interface at different time through resolving the level set function 水平集方法是把最初给定的截面(原始曲线或面)看作是某个函数零集，把求解等距过程中发生的拓扑等现象转移到高一维的水平集函数中去，通过求解该水平集函数以得到原始截面不同时刻的等距面。
In 2001 , professor zhang defined the inclusion variations , disjoint variations and chain variations of set functions , and then discussed the properties of the three kinds of variations . he found that variations play an important role in the decompositions of signed fuzzy measures and signed lower semicontinuous fuzzy measures , just as they do for signed measures , additive fuzzy measures , non - monotonic fuzzy measures and t - measures 2001年，在论文《 somepropertiesofthevariationsofnon - additivesetfunctions 》和《 somepropertiesofthevariationsofnon - additivesetfunctions 》中，张强教授提出了集函数的内含变差，不交变差和链变差的概念，并详细讨论了这三种变差的性质。
