%N 6 %J Comptes rendus math?matique %R doi:10.1016/j.crma.2007.07.020 %A Irene Crimaldi %A Giorgio Letta %A Luca Pratelli %X We characterize the measurable spaces (?,A) such that, for each sub-?-field G of A and each decreasing filtered family (F_t) of sub-?-fields of A, with F_t ? F_?, we have F_t ? G ? F_? ? G. It follows a characterization of the probability spaces (?, A, P) such that, for each sub-?-field G of A and each decreasing sequence (F_n) of sub-?-fields of A, with F_n ? F_?, we have ?_n (F_n ? G) ? F_? ? G (mod P). %L eprints984 %D 2007 %I Elsevier Masson %V 345 %T Sur l'interversion de l'ordre entre deux op?rations sur les tribus %P 341-344