III: 05, 97-114, LNM 88 (1969) DELLACHERIE, Claude Ensembles aléatoires I (Descriptive set theory, Markov processes, General theory of processes) A deep theorem of Lusin asserts that a Borel set with countable sections is a countable union of Borel graphs. It is applied here in the general theory of processes to show that an optional set with countable sections is a countable union of graphs of stopping times, and in the theory of Markov processes, that a Borel set which is a.s. hit by the process at countably many times must be semi-polar Comment: See Dellacherie, Capacités et Processus Stochastiques, Springer 1972 Keywords: Sets with countable sections Nature: Original Retrieve article from Numdam