Dirichlet form approach to diffusions with discontinuous scale

Abstract: It is well known that a regular diffusion on an interval $I$ without killing inside is uniquely determined by a canonical scale function $s$ and a canonical speed measure $m$. Note that $s$ is a strictly increasing and continuous function and $m$ is a fully supported Radon measure on $I$. In this paper we will associate a general triple $(I,s,m)$, where $s$ is only assumed to be increasing and $m$ is not necessarily fully supported, to certain Markov processes by way of Dirichlet forms. A straightforward generalization of Dirichlet form associated to regular diffusion will be first put forward, and we will find out its corresponding continuous Markov process $\dot X$, for which the strong Markov property fails whenever $s$ is not continuous. Then by operating regular representations on Dirichlet form and Ray-Knight compactification on $\dot X$ respectively, the same unique desirable symmetric Hunt process associated to $(I,s,m)$ is eventually obtained. This Hunt process is homeomorphic to a quasidiffusion, which is known as a celebrated generalization of regular diffusion.