Ovidiu Radulescu Université de Montpellier 2 Title: Reduction of biochemical networks with multiple time scales Abstract: Biochemical networks are used in computational biology, to model mechanistic details of systems involved in cell signaling, metabolism, regulation of gene expression. Parametric and structural uncertainty, as well as combinatorial explosion are strong obstacles against analyzing the dynamics of large models of this type. Multi-scaleness is another property of these networks, that can be used to get past some of these obstacles. Network with many, well separated, time scales, can be reduced to simpler networks, in a way that does not depend on the exact values of the parameters, but on their order relations. I will show how tropical geometry can be used to unify various approaches to this problem, also provide examples from signaling and cell cycle regulation to illustrate these ideas.