The Unknown Component Problem pp 195-210 | Cite as

# Computation of Sequential Flexibility in Networks of FSMs by Windowing

## Abstract

This chapter addresses the problem of resynthesizing the component FSMs of a network of FSMs; we will discuss both a global approach and a local (windowing) approach. It will turn out that sometimes it is more effective to solve a system of equations instead of a single equation; therefore we will introduce systems of equations over FSMs. The motivation is that, when optimizing a component FSM by solving a single monolithic equation, the context and the specification may be so huge for real sequential circuits, that they will be difficult to build. Using the fact that the synchronous composition operator is associative, we will see that the task may be simplified by applying a window approach, where we replace the solution of a single large equation by the solution of a system of simpler equations. In the windowing approach, the specification is restricted to be the composition of only two component FSMs, and the context to a single component FSM, so that the computational effort is reduced with respect to the general case, where the specification is the composition of all component FSMs and the context is the composition of all but one (the one to be resynthesized) component FSMs. For the sake of simplicity, all component FSMs are assumed to be complete and deterministic.

## Notes

### Acknowledgements

We thank Maria Vetrova and Svetlana Zharikova for their contribution to this chapter from their dissertations at the University of Tomsk [134, 154].