1. A method of partitioning a model comprising a plurality of variables representing state elements, the method comprising: select a variable from the plurality of variables; identify a first set of variables among the plurality of variables that each support said selected variable; identify a second set of variables among the plurality of variables that each have support overlapping said first set of variables; and storing said second set of variables on a machine readable medium; wherein said second set of variables is a partition of state elements suitable for use in determining an overapproximation of reachable states of said selected variable.