XIII: 08, 118-125, LNM 721 (1979) YOEURP, Chantha Sauts additifs et sauts multiplicatifs des semi-martingales (Martingale theory, General theory of processes) First of all, the jump processes of special semimartingales are characterized (using a result of 1121, 1129 on the jump processes of local martingales). Then a similar problem is solved for multiplicative jumps, a result which includes that of Garcia and al. 1206. A technical lemma characterizes optional processes, bounded in $L^1$, whose previsible projection vanishes Keywords: Jump processes Nature: Original Retrieve article from Numdam