New Approximation Algorithms for the Minimum Cycle Cover Problem

Abstract

Given an undirected weighted graph $G=(V,E)$ with nonnegative weight function obeying the triangle inequality, a set $\{C_1,C_2,\ldots ,C_k\}$ of cycles is called a cycle cover if $V \subseteq \bigcup _{i=1}^k V(C_i)$ and its cost is given by the maximum weight of the cycles. The Minimum Cycle Cover Problem aims to find a cycle cover of cost at most $\lambda$ with the minimum number of cycles. An $O(n^2)$ 24/5-approximation algorithm and an $O(n^5)$ 14/3-approximation algorithm are given by Yu and Liu (Theor Comput Sci 654:45–58, 2016). However, the original proofs for approximation ratios are incomplete. In this paper we first present a corrected simplified analysis on the 24/5-approximation algorithm. Then we give a new $O(n^3)$ approximation algorithm that achieves the same ratio 14/3 and has much simpler proof on the approximation ratio. Moreover, we derive an improved 32/7-approximation algorithm that runs in $O(n^5)$.