Finite Thurston type orderings on dual braid monoids

Abstract

For a finite Thurston type ordering < of the braid group B_{n}, we introduce a new normal form of a dual positive braid which we call the C-normal form. This normal form extends Fromentin's rotating normal form and the author's C-normal form of positive braids. Using the C-normal form, we give a combinatorial description of the restriction of the ordering < to the dual braid monoids B_{n}^{+*}. We prove that the restriction to the dual positive monoid (B_{n}^{+*},<) is a well-ordered set of order type ω^{ω^{n-2}}.