We introduce (finite and infinite) typical paths of a graph and prove that the typical paths carry all information with probability 1, asymptotically. An automata-theoretic characterization of the typical paths is shown: finite typical paths can be accepted by reversal-bounded multicounter automata and infinite typical paths can be accepted by counting Büchi automata (a generalization of revers...

We consider past pushdown timed automata that are discrete pushdown timed automata [15] with past-formulas as enabling conditions. Using past formulas allows a past pushdown timed automaton to access the past values of the finite state variables in the automaton. We prove that the reachability (i.e., the set of reachable configurations from an initial configuration) of a past pushdown timed aut...

Microscopic traffic models have recently gained considerable importance as a mean of optimising traffic control strategies. Computationally efficient and sufficiently accurate microscopic traffic models have been developed based on the cellular automata theory. However, the real-time application of the available cellular automata models in traffic control systems is a difficult task due to thei...

The family of deterministic input-driven pushdown automata (IDPDA; a.k.a. visibly pushdown automata, a.k.a. nested word automata) is known to be closed under reversal, concatenation and Kleene star. As shown by Alur and Madhusudan (“Visibly pushdown languages”, STOC 2004), the reversal and the Kleene star of an n-state IDPDA can be represented by an IDPDA with 2 2) states, while concatenation o...

We introduce discrete pushdown timed automata that are timed automata with integer-valued clocks augmented with a pushdown stack. A connguration of a discrete pushdown timed automaton includes a control state, nitely many clock values and a stack word. Using a pure automata-theoretic approach, we show that the binary reachability (i.e., the set of all pairs of conngurations (;), encoded as stri...

It is proved for some "nice" function / that/(fl)-reversal-bounded two-way nondeterministic finite automata are more powerful than /(n)-reversal-bounded two-way deterministic ones. This solves a simplified extension of the well-known DLOG ? NLOG problem.