Theory of Codes
Automated composition of e-services: lookaheads
Proceedings of the 2nd international conference on Service oriented computing
Generalizations of 1-deterministic regular languages
Information and Computation
Composability of infinite-state activity automata
ISAAC'04 Proceedings of the 15th international conference on Algorithms and Computation
Quotient complexity of closed languages
CSR'10 Proceedings of the 5th international conference on Computer Science: theory and Applications
Quotient Complexity of Closed Languages
Theory of Computing Systems
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We introduce a new class of nondeterministic semiautomata: A nondeterministic semiautomaton S is predictable if there exists k=0 such that, if S knows the current input a and the next k inputs, the transition under a can be made deterministically. Nondeterminism may occur only when the length of the unread input is @?k. We develop a theory of predictable semiautomata. We show that, if a semiautomaton with n states is k-predictable, but not (k-1)-predictable, then k@?(n^2-n)/2, and this bound can be reached for a suitable input alphabet. We characterize k-predictable semiautomata, and introduce the predictor semiautomaton, based on a look-ahead semiautomaton. The predictor is essentially deterministic and simulates a nondeterministic semiautomaton by finding the set of states reachable by a word w, if it belongs to the language L of the semiautomaton (i.e., if it defines a path from an initial state to some state), or by stopping as soon as it infers that w@?L. Membership in L can be decided deterministically.