Finding Closed Partitions for State Assignments in Subset-Specified Sequential Machines.

摘要

Purnhagen has developed a method of state reduction for Subset-Specified Sequential Machines (SSSMs). Flowtable entries for these machines may be conditional Don't-Cares. An SSSM can select from any of the allowed next-state/output pairs in an entry upon each transition to that entry. Incompletely specified and completely specified machines are special cases of SSSMs. When state-reduced an incompletely specified machine may also contain optional entries. A method of computing closed partitions for completely specified and incompletely specified machines is developed. The method uses transitivity properties of the machines,and uses step tables to record the building of closed partition blocks. The method is applied to SSSMs and allows selection from the optional entries so as to maximize closed partitions in the machines. This selection process reduces the SSSM to an incompletely specified or to a completely specified machine,and state assignment can be completed using existing techniques.