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State Based Control of Timed Discrete Event Systems using Binary ...

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Chapter 4Synthesis Algorithm <strong>Based</strong> onPredicates4.1 PredicatesIn order to place conditions on the states <strong>of</strong> the system G, it will be convenient to use alogic formalism. A predicate P defined on Q is a function P : Q → {0, 1}. P can alwaysbe identified with the corresponding state subset (“Truth Set”)Q P := {q ∈ Q | P (q) = 1}.For clarity, if P (q) = 1, we write q P , otherwise q P .Note: P red(Q) is the set <strong>of</strong> all the predicates on Q.For s ∈ Σ ∗ we say t ∈ Σ ∗ is a prefix <strong>of</strong> s, and write t ≤ s, if s = tu for some u ∈ Σ ∗ . Wedefine the closed languageL(G, P ) induced by a predicate P ∈ P red(Q) to beL(G, P ) := {w ∈ L(G) | (∀v ≤ w)δ(q 0 , v) P }That is, the set <strong>of</strong> strings that are generated by G and leads us to a state which satisfiesP through a path <strong>of</strong> states that all satisfy P .21

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