Abstract In this paper, we consider a model of generalized timed automata (GTA) with two kinds clocks, history and future , that can express many features succinctly, including automata, event-clock without diagonal constraints, timers. Our main contribution is new simulation-based zone algorithm for checking reachability in unified model. While such algorithms are known to exist have recently ...

Modelling distributed systems requires notions as locations, communication among the distributed processes, and resource access. To express time constraints for such systems, we have introduced timed distributed π-calculus called tDπ as an extension of the π-calculus with locations, types and timers. Timers define both timeouts for communication channels and timeouts for resources. We define th...

Most embedded real-time systems consists of many concurrent components operating at signi cantly different speeds. Thus, an algorithm for formal verication of such systems must e ciently deal with a large number of states and large ratios of timing constants. We present such an algorithm based on timed automata, a model where a nite state system is augmented with time measuring devices called t...

In 1971, I spent five months in Ghana, West Africa, collecting data for an MSc thesis, "On the Ecology and Fishery of a Small West African Lagoon". I was puzzled at the time by the behavior of the fishermen who exploited the Sakumo lagoon, near Tema (Fig. 1). Based in a nearby village, they were part-timers or full-timers, but fished in either case rarely more than about 4 hours at a time, then...

Recent literature shows how the destabilising e¤ect of portfolio insurance activity on the price of the underlying asset depends on the liquidity of the asset market. We build a simple model where market timers shift capital around asset markets in order to exploit gains from temporary excess-volatility of asset prices. In this way, market timers increase the liquidity of asset markets reducing...