Binary Reachability Analysis of

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 strings, such that can reach through 0 or more transitions) can be accepted by a nonde-terministic pushdown machine augmented with reversal-bounded counters (NPCM). Since discrete timed automata with integer-valued clocks can be treated as discrete pushdown timed automata without the push-down stack, we can show that the binary reachability of a discrete timed automaton can be accepted by a nondeterministic reversal-bounded mul-ticounter machine. Thus, the binary reachability is Presburger. By using the known fact that the emptiness problem is decidable for reversal-bounded NPCMs, the results can be used to verify a number of properties that can not be expressed by timed temporal logics for discrete timed automata and CTL for pushdown systems.