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Hybrid automata model systems with both digital and analog components, such as embedded control programs. Many veriication tasks for such programs can be expressed as reachability problems for hybrid automata. By improving on previous decidability and undecidability results, we identify a boundary between decidability and undecidability for the reachability(More)
In this paper, we present an algorithm for routing in wireless ad hoc networks using information about geographical location of the nodes. We assume each node knows its geographical position and the position of the node to which it wants to send a packet. Initially, the nodes only know their neighbors but over time they discover other nodes in the network.(More)
In IEEE 802.11 wireless LANs, the DCF access method and the PCF access method operate alternatively within a superframe to service the time-varying traffic demands. Due to different medium access mechanisms deployed by DCF and PCF, they work well for some particular types of traffic scenarios respectively, while their performance may degrade under some(More)
Proof: 2 L(H D) (2 L(H C)) provided there is a sequence =< D(l 0); 0 ; 0 >< D(l 1); 1 ; 1 > : : : which is discrete-time (continuous-time) consistent. As discussed at beginning of Sect. 3, every discrete-time consistent sequence is continuous-time consistent. From Lemma 3-Lemma 7, every continuous-time consistent sequence is also discrete-time consistent.(More)