%0 Journal Article %T A new generalization of the Lelong number %A Aron Lagerberg %J Mathematics %D 2010 %I arXiv %X We introduce a quantity which measures the singularity of a plurisubharmonic function f relative to another plurisubharmonic function g, at a point a. This quantity, which we denote by $\nu_{a,g}(f)$, can be seen as a generalization of the classical Lelong number, in a natural way. The main theorem of this article says that the upper level sets of our generalized Lelong number, i.e. the sets of the form $\{z: \nu_{z,g}(f) \geq c > 0 \}$, are in fact analytic sets, under certain conditions on the weight g. %U http://arxiv.org/abs/1001.3562v1