ThisbookistheresultoftheInternationalSymposiumonSemiMarkovProcessesandtheirApplicationsheldonJune4-7,1984attheUniversiteLibredeBruxelleswiththehelpoftheFNRS(FondsNationaldelaRechercheScientifique,Belgium),theMinisteredel'EducationNationale(Belgium)andtheBernoulliSocietyforMathem