土地分类的集合表述与特征分析

Set Features Analysing and Signification of Land Classification

把全国土地看作一个集合Ａ，其第一级元素是３０个省（自治区）与直辖市，第二级是市（地区），第三级为县（区），第四级为乡、镇或小区，第五级为村或街道，第六级为土地单元；同时把土地分类的８个一级分类和４６个二级分类以及城镇与铁路的部分三级分类当作土地利用类型集合Ｓ的元素．集合Ａ与集合Ｓ都具有极小元与奇异性，Ａ与Ｓ本元的交集可唯一地确定一个土地单元的属性与类型，建立起土地分类系统的集合表述数学模型，为土地分类的计算机化提供了依据与手段．

This paper takes the national land as set A in which the first class elements are the 27 provinces(autonomous regions) and 3 municipalities directly under the Central Government, the second class elements are cities/subprovincial administrative regions, the third class elements are counties/districts, the fourth class elements are counties/towns, the fifth class elements are villages and the sixth class elements are land unit elements ;it also takes the eight first class and fourty six second class classifications of land use and some third class classifications of city and railway as the elements of land use classification set S. Both set A and set S have the minimal element and singularity,and the intersection set of the primitive elements of set A and set S can uniquely determine the property or classification of a land unit, thus the mathematical model and set expression of land classification are established , which provide the foundation and means for the creation of land classification system and its computerizing.