Model-Checking an Alternating-time Temporal Logic with Knowledge, Imperfect Information, Perfect Recall and Communicating Coalitions

We present a variant of ATL with distributed knowledge operators based on a synchronous and perfect recall semantics. The coalition modalities in this logic are based on partial observation of the full history, and incorporate a form of cooperation between members of the coalition in which agents issue their actions based on the distributed knowledge, for that coalition, of the system history. We show that model-checking is decidable for this logic. The technique utilizes two variants of games with imperfect information and partially observable objectives, as well as a subset construction for identifying states whose histories are indistinguishable to the considered coalition

Relatório de estágio em farmácia comunitária

Relatório de estágio realizado no âmbito do Mestrado Integrado em Ciências Farmacêuticas, apresentado à Faculdade de Farmácia da Universidade de Coimbr

A study on shuffle, stopwatches and independently evolving clocks

We show that stopwatch automata are equivalent with timed shuffle expressions, an extension of timed regular expressions with the shuffle operation. Since the emptiness problem is undecidable for stopwatch automata, and hence also for timed shuffle expressions, we introduce a decidable subclass of stopwatch automata called partitioned stopwatch automata. We give for this class an equivalent subclass of timed shuffle expressions and investigate closure properties by showing that partitioned stopwatch automata are closed under union, concatenation, star, shuffle and renaming, but not under intersection. We also show that partitioned stopwatch automata are equivalent with distributed time-asynchronous automata, which are asynchronous compositions of timed automata in which time may evolve independently

Distributed time-asynchronous automata

Abstract. We show that the class of distributed time-asynchronous automata is more expressive than timed automata, has a decidable emptiness problem, is closed under union, concatenation, star, shuffle and renaming, but not under intersection. The closure results are obtained by showing that distributed time-asynchronous automata are equivalent with a subclass of shuffle regular expressions and its related class of stopwatch automata.

On Deducible Information Flow in Synchronous Models

We revisit the synchronous model of Wittbold and Johnson of information flow, by investigating the relationship between two notions of information flow: a notion based on counting differently-observable high-level strategies and a notion based on the deductions that the low-level user makes on high-level activity while observing system behavior. We then relate our results to some known models of information flow: we show that bisimulation-based equivalence checking is too strong, since it labels variations in the observation due to system nondeterminism as information flow.We also show that a synchronous, trace-based statement of Generalized Noninterference does not properly capture information flow either. Finally we give a decision procedure for detecting information flow for finitestate systems

VESICOURETERAL REFLUX THE IMPORTANCE OF DIAGNOSTIC IMAGING IN CHILDREN

We present our experience with 303 children presenting vesicoureteral reflux, regarding the use of diagnostic imaging. Voiding cystouretrography remains the mean technique in diagnostic and grading vesicoureteral reflux. It can be replaced by voiding cystouretrosonography for follow-up. Urography and ecography are needed for diagnose of primary or secondary type vesicoureteral reflux. Nuclear imaging is useful in precising the renal function and demonstrating renal scaring