A Ray-Knight representation of up-down Chinese restaurants

TL;DR

This paper introduces a novel Ray-Knight representation linking up-down Chinese Restaurant Processes with spectrally positive Lévy processes, providing new insights and limit theorems in the study of composition-valued Markov chains.

Contribution

It develops a Ray-Knight type theorem connecting up-down CRPs to Lévy processes and establishes limit theorems relating to interval partition diffusions.

Findings

Established a new representation of up-down CRPs via Lévy processes.

Proved limit theorems connecting CRPs to interval partition diffusions.

Linked the dynamics of CRPs to long-standing conjectures in stochastic processes.

Abstract

We study composition-valued continuous-time Markov chains that appear naturally in the framework of Chinese Restaurant Processes (CRPs). As time evolves, new customers arrive (up-step) and existing customers leave (down-step) at suitable rates derived from the ordered CRP of Pitman and Winkel (2009). We relate such up-down CRPs to the splitting trees of Lambert (2010) inducing spectrally positive L\'{e}vy processes. Conversely, we develop theorems of Ray-Knight type to recover more general up-down CRPs from the heights of L\'{e}vy processes with jumps marked by integer-valued paths. We further establish limit theorems for the L\'{e}vy process and the integer-valued paths to connect to work by Forman et al. (2018+) on interval partition diffusions and hence to some long-standing conjectures.