The abstraction function maps configurations of the EFSM into abstract states of the abstraction FSM using a finite set of predicates and a finite set of selected input parameter valuations.
When there is no separating sequence for the sets of abstract states of an abstraction FSM, we refine the current FSM abstraction and try to find such a sequence using the refined abstraction.
A problem that can arise in using abstraction is the generation of abstract states, called spurious states, from which the goal state is reachable in the abstract space but for which there is no corresponding state in the original space from which the goal state can be reached.
A refined FSM abstraction M D has more abstract states than M B and this usually reduces the degree of non-determinism in M D compared with M B and thus increases the chance of the existence of a separating sequence.
An abstraction function that maps configurations and transitions of the EFSM specification to corresponding abstract states and transitions of the abstraction FSM is proposed.
If a distinguishing sequence for the corresponding two sets of abstract states is not found using the current FSM abstraction, the abstraction is refined.
Derive an FSM abstraction of M Consider the sets of abstract states S′ and S′′ that correspond to the sets of configurations C′ and C′′, respectively.
Here we provide an algorithm for the method given above for distinguishing two disjoint sets of configurations C′ and C′′ by deriving a separating sequence for the corresponding sets of abstract states S′ and S′′ in a corresponding abstraction FSM.
In both cases, after deriving an FSM abstraction, determining a sequence that distinguishes the two given sets of EFSM configurations is done by finding a separating sequence for the corresponding sets of abstract states S′ and S′′ in the FSM abstraction.
In this section we present an algorithm for distinguishing two disjoint sets of configurations C′ and C′′ of an EFSM M by deriving a separating sequence for the corresponding sets of abstract states S′ and S′′ in the corresponding FSM abstraction.
The abstract states S′ and S′′ are non-separable in such FSM abstraction.
