Joseph Y. Halpern

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Many ad hoc routing protocols are based on some variant of flooding. Despite various optimizations of flooding, many routing messages are propagated unnecessarily. We propose a gossiping-based approach, where each node forwards a message with some probability, to reduce the overhead of the routing protocols. Gossiping exhibits bimodal behavior in(More)
The differences between and appropriateness of branching versus linear time temporal logic for reasoning about concurrent programs are studied. These issues have been previously considered by Lamport. To facilitate a careful examination of these issues, a language, CTL<supscrpt>*</supscrpt>, in which a universal or existential path quantifier can prefix an(More)
We consider two approaches to g iv ing semantics to first order logics of probabi l i ty . The first approach puts a probabi l i ty on the domain, and is appropr iate for g iv ing semantics to formulas involv ing stat ist ical in format ion such as "The probabi l i ty that a ( typ ica l ) b i rd flies is greater than .9." The second approach puts a probabi(More)
Several new logics for belief and knowledge are introduced and studied, all of which have the property that agents are not logically omniscient. In particular, in these logics, the set of beliefs of an agent does not necessarily contain all valid formulas. Thus, these logics are more suitable than traditional logics for modelling beliefs of humans (or(More)
In this paper we consider the Computation Tree Logic (CTL) proposed in [CE] which extends the Unified Branching Time Logic (UB) of [BMP] by adding an <italic>until</italic> operator. We establish that CTL has the small property by showing that any satisfiable CTL formulae is satisfiable in a small finite model obtained from a small(More)
We study <i>k-resilient Nash equilibria</i>, joint strategies where no member of a coalition <i>C</i> of size up to <i>k</i> can do better, even if the whole coalition defects. We show that such <i>k</i>-resilient Nash equilibria exist for secret sharing and multiparty computation, provided that players prefer to get the information than not to get it. Our(More)