关于一类三交系的构造

A Way of Forming a Type of 3-intersecting System of Sets

本文首先定义了三交系、三交系的扩充的概念 ,然后给出了一类三交系的构造方法 ,最后给出了该类三交系的规模的统一公式表示。同时 。

Denote X={1,2,...,n}, n≥1. In this article, a 3-intersecting system of sets of X and the extension of a 3-intersecting system of sets are firstly defined. Then we give a method on how to extend a type of 3-intersecting system of sets. At last, we get a general formulation of the modulus of the 3-intersecting system of sets. As the by-production, we get the necessary and sufficient condition of a special type of 3-intersecting systems of sets of X.