Non-bi-orderability of $6_2$ and $7_6$

Abstract

We prove that the knot groups of $6_2$ and $7_6$ are not bi-orderable. These are the only two knot groups up to 7 crossings whose bi-orderability was not known. Our method applies to a very broad class of knots.

13 pages, 4 figures. We added some details. Comments are welcome