Ranking tournaments with no errors II: Minimax relation

Xujin Chen, Guoli Ding, Wenan Zang, Qiulan Zhao

Abstract: A tournament T=(V,A)<math><mi is="true">T</mi><mo linebreak="goodbreak" linebreakstyle="after" is="true">=</mo><mo stretchy="false" is="true">(</mo><mi is="true">V</mi><mo is="true">,</mo><mi is="true">A</mi><mo stretchy="false" is="true">)</mo></math> is called cycle Mengerian (CM) if it satisfies the minimax relation on packing and covering cycles, for every nonnegative integral weight function defined on A. The purpose of this series of two papers is to show that a tournament is CM iff it contains none of four Möbius ladders as a subgraph; such a tournament is referred to as Möbius-free. In the first paper we have given a structural description of all Möbius-free tournaments, and have proved that every CM tournament is Möbius-free. In this second paper we establish the converse by using our structural theorems and linear programming approach.