# Chapter 12 Coupling Theory and Examples (October 11, 1999)

xxx This is intended as a section in a Chapter near Chapter 4; maybe a new Chapter consisting of this and another section on bounding $\tau_{2}$ via distinguished paths. Need some preliminary discussion, e.g. on

relations between $\tau_{1}$ and $\tau_{2}$;

observe that $\tau_{2}$ is tied to reversibility whereas coupling isn’t.