The state-based approach plays an important role in modeling and control of Discrete-Event Systems (DES). Based on previous work, state feedback control of DES with nonblocking is thoroughly investigated; a general construction method for memory and the corresponding predicate is also specified. Two examples are provided in illustration. Also presented is state-based control of DES with observational abstraction. Based on the existing idea of quasi-congruence, quasi-observer, as a kind of observational abstraction, is developed; its advantages and limitations are discussed by means of simple examples. Imposing an observational partition on the state set also leads to observational abstraction. On this basis, the state-feedback controller design is introduced; in particular, the notion of high and low modeling levels for DES is proposed, based on which reachability and controllability are further discussed and compared. Finally, two simple applications are provided to show the advantage of observational partition in DES analysis and control.

The state-based approach plays an important role in modeling and control of Discrete-Event Systems (DES). Based on previous work, state feedback control of DES with nonblocking is thoroughly investigated; a general construction method for memory and the corresponding predicate is also specified. Two examples are provided in illustration. Also presented is state-based control of DES with observational abstraction. Based on the existing idea of quasi-congruence, quasi-observer, as a kind of observational abstraction, is developed; its advantages and limitations are discussed by means of simple examples. Imposing an observational partition on the state set also leads to observational abstraction. On this basis, the state-feedback controller design is introduced; in particular, the notion of high and low modeling levels for DES is proposed, based on which reachability and controllability are further discussed and compared. Finally, two simple applications are provided to show the advantage of observational partition in DES analysis and control.