Isabel Nunes

Luís Cruz-Filipe, Graça Gaspar, Isabel Nunes

Continuous queries over data streams may suffer from blocking operations and/or unbound wait, which may delay answers until some relevant input arrives through the data stream. These delays may turn answers, when they arrive, obsolete to users who sometimes have to make decisions with no help whatsoever. Therefore, it can be useful to provide hypothetical answers - "given the current information, it is possible that X will become true at time t" - instead of no information at all. In this paper we present a semantics for queries and corresponding answers that covers such hypothetical answers, together with an online algorithm for updating the set of facts that are consistent with the currently available information.

Isabel Nunes, Filipe Luís

In this paper we focus on exploiting a specification and the structures that satisfy it, to obtain a means of comparing implemented and expected behaviours and find the origin of faults in implementations. We present an approach to the creation of tests that are based on those specification-compliant structures, and to the interpretation of those tests' results leading to the discovery of the method responsible for an eventual test failure. Results of comparative experiments with a tool implementing this approach are presented.