Non-left-orderable double branched coverings

Abstract

We develop a method to show the fundamental group of the double branched covering of links is not left-orderable by introducing a notion of coarse presentation. Like usual group presentations, a coarse presentation is given by a set of generators and relations, but inequalities are allowed as relations. By using coarse presentations, we give a family of links whose double branched covering has non-left-orderable fundamental group. Our family of links includes many known and new examples.