This paper presents a calculus inspired by the spiking neural P systems. Its operational and denotational semantics are defined; they are related by using the metric semantics methodology, showing that the denotational semantics is correct with respect to the operational one. We use the continuations for concurrency to describe precisely the nondeterministic behaviour, the time delays between firings and spikings, as well as the synchronized functioning specific to spiking neural P systems.

The paper proposes a high-level model to represent spatio-temporal relations between Web sites or fragments of Web sites in order to facilitate resource discovery, cataloging or describe information. This model is based on the Resource Description Framework (RDF) recommendation of the World-Wide Web Consortium, a general purpose technology that enables the description of resources on the Web. The representation of the spatio-temporal relationships is expressed by an XML-based language.