The two-parameter generalization of Ewens' random partition structureUCB Statistics Technical Report #345Jim PitmanDepartment of Statistics ,University of California, Berkeley}March 1992; reprinted with an appendix and updated references July 2003A two-parameter generalization of Ewens' random partition structure is obtained
by sampling from a random discrete distribution derived by Perman, Pitman and Yor from the
lengths of excursions of a recurrent Bessel process.9?????engUniversity of California at Berkeley, Berkeley, Californiatechnical reportstechnical reportshttp://www.stat.berkeley.edu/new-tech-reports/345.pdfThe author(s)