Epsilon multiplicity and analytic spread of filtrations

Abstract: We extend the epsilon multiplicity of ideals defined by Ulrich and Validashti to epsilon multiplicity of filtrations, and show that under mild assumptions this multiplicity exists as a limit. We show that in rather general rings, the epsilon multiplicity of a Q-divisorial filtration is positive if and only if the analytic spread of the filtration is maximal (equal to the dimension of the ring). The condition that filtrations $\mathcal J\subset \mathcal I$ have the same epsilon multiplicity is considered, and we find conditions ensuring that the filtrations have the same integral closure.