對偶超圖之著色數探討

Abstract

本文藉構造bipartite graph 的形式討論超圖與對偶超圖的transversal number，進而探討最小著色數的上界，以及證明出此兩圖的最小著色數可差異很大，也可用此方法構造出想要的最小著色數之差異。最後探討在某些情形下，超圖與其對偶超圖的同構性，再則整理出其必要條件。

H=(X,D) is called a hypergraph, where X is the vertex set and D is a family of subsets of X, denoted as D-edges, and we assume that every D-edges have at least two elements. A strict t-coloring is a onto mapping from X to {1,2,....,t} such that each D contained in D-edge set has two vertices having distinct values. The maximum(minimum) number of colors over all strict k-coloring is called the upper(lower) chromatic number and is denoted as .

Abstract.......................................................i\r\n1.Introduction.................................................1\r\n2.The difference between the transversal numbers of H and H*...4\r\n3.Isomorphism.................................................12\r\n4.Conclusions.................................................16\r\nReferences....................................................17