Abstract-Occurrence nets are a well known partial order model for the concurrent behavior of Petri nets. The causality and conflict relations between events, which are explicitly represented in occurrence nets, induce logical dependencies between event occurrences: the occurrence of an event e in a run implies that all its causal predecessors also occur, and that no event in conflict with e occurs. But these structural relations do not express all the logical dependencies between event occurrences in maximal runs: in particular, the occurrence of e in any maximal run may imply the occurrence of another event that is not a causal predecessor of e, in that run. The reveals relation has been introduced in [1] to express this dependency between two events. Here we generalize the reveals relation to express more general dependencies, involving more than two events, and we introduce ERL logic to express them as boolean formulas. Finally we answer the synthesis problem that arises: given an ERL formula ϕ, is there an occurrence net N such that ϕ describes exactly the dependencies between the events of N ?

This article proposes two approaches to tool-supported automatic verification of dense real-time systems against scenario-based requirements, where a system is modeled as a network of timed automata (TAs) or as a set of driving live sequence charts (LSCs), and a requirement is specified as a separate monitored LSC chart.We make timed extensions to a kernel subset of the LSC language and define a tracebased semantics. By translating a monitored LSC chart to a behavior-equivalent observer TA and then non-intrusively composing this observer with the original TA-modeled realtime system, the problems of scenario-based verification reduce to computation tree logic (CTL) real-time model checking problems. When the real-time system is modeled as a set of driving LSC charts, we translate these driving charts and the monitored chart into a behaviorequivalent network of TAs by using a "one-TA-per-instance line" approach, and then reduce the problems of scenario-based verification also to CTL real-time model checking problems. We show how we exploit the expressivity of the TA formalism and the CTL query language Form Methods Syst Des (2010) 37: 200-264 201 of the real-time model checker UPPAAL to accomplish these tasks. The proposed two approaches are implemented in the UPPAAL tool and built as a tool chain, respectively. We carry out a number of experiments with both verification approaches, and the results indicate that these methods are viable, computationally feasible, and the tools are effective.

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