2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/127830We show that for $0<α<1$ and $θ>-α$, the Poisson-Dirichlet distribution with parameter $(α, θ)$ is the unique reversible distribution of a rather natural fragmentation-coalescence process. This completes earlier results in the literature for certain split and merge transformations and the parameter $α=0$.Probability60 J 25 ; 60 J 27text