Title: Matrix Modelling Toby Walsh, Cork Constraint Computation Centre, Cork, Ireland (joint work with A. Frisch, B. Hnich, Z. Kiziltan, and I. Miguel) Many companies have scheduling, assignment, supply chain and other problems that could be solved with a constraint programming (CP) toolkit. A major bottleneck in solving such problems is modelling such problems in terms of variables with domains of values and constraints. As in other areas of software engineering, many "patterns" occur frequently in constraint programs. In this talk, I will identify some patterns common to constraint programs taken from a wide range of domains. The basis for these patterns comes from identifying the central role played in many constraint programs by matrices of decisions variables, and the common types of constraint posted on such matrices.