对于划分的粒度,现在已经定义了很多公式.相对于同一个论域来说,这些定义所遵循的一个整体的原则显然是划分块数越少其粒度越大.对于同一论域的具有相同块数的两个不同划分,在某些情况下,其粒度也被认为是不同的,可称之为局部原则.现有的公式基本上都兼顾了这两个方面.讨论一个相对简单的公式,且主要研究的是局部原则对整体原则某种程度的破坏.首先定义划分的方差,给出划分的粒度公式与划分的方差之间的关系.然后给出一个界限,证明在相同论域上,当一个划分的块数大于另一个划分的块数超过这个界限时,这个划分的粒度一定大于另一个划分的粒度.
There are a number of definitions of granularity based on partitions. Generally, fewer partition blocks correspond to larger granularity. In some cases, the granularities of two different partitions with the same number of blocks may be viewed different. These two issues are called the general principle and the local principle, respectively. This paper discusses a simple definition,and focuses on the violation of the general principle by the local one. First, we define the variance of partitions, and discuss the relationship between the granularity formulas of partitions and the variance of partitions. Then we prove that if the number of the blocks of a partition is bigger than another beyond a given limit, lhe granularity of the partition is definitely bigger than the other.