Feedback numbers of de Bruijn digraphs

  • Authors:
  • Xirong Xu;Yongchang Cao;Jun-Ming Xu;Yezhou Wu

  • Affiliations:
  • Department of Computer Science, Dalian University of Technology, Dalian, 116024, China and Department of Mathematics, University of Science and Technology of China, Hefei, Anhui, 230026, China;Department of Mathematics, University of Science and Technology of China, Hefei, Anhui, 230026, China;Department of Mathematics, University of Science and Technology of China, Hefei, Anhui, 230026, China;Department of Mathematics, University of Science and Technology of China, Hefei, Anhui, 230026, China

  • Venue:
  • Computers & Mathematics with Applications
  • Year:
  • 2010

Quantified Score

Hi-index 0.09

Visualization

Abstract

A subset of vertices of a graph G is called a feedback vertex set of G if its removal results in an acyclic subgraph. Let f(d,n) denote the minimum cardinality over all feedback vertex sets of the de Bruijn digraph B(d,n). This paper proves that for any integers d=2 and n=2f(d,n)={1n@?i|nd^i@f(ni)for 2@?n@?4;d^nn+O(nd^n^-^4)for n=5, where i|n means i divides n, and @f(i) is the Euler totient function.