Brink and Howlett
[Math. Ann.296:1 (1993), 179–190] have introduced a partial ordering,
called dominance, on the root systems of Coxeter groups in their proof that
all finitely generated Coxeter groups are automatic. Edgar (Ph.D. thesis,
2009), in an investigation of various regularity properties of Coxeter groups,
studied a function on the reflections of such groups, called ∞-height. Here
we show that these two concepts are closely related to each other. We also
give applications of dominance to the study of imaginary cones of Coxeter
groups.