Hybrid Models for Mobile Computing

Hybrid specifications, i.e. ones containing both discrete and continuous changes, are used mainly in modelling systems that control some physical phenomena. In this paper, we propose hybrid modelling of novel wireless mobile systems, which generally fall under the term mobile computing. The particular systems consist of agents capable of moving in a physical reality and communicating wirelessly when in each other's proximity. In this paper we concentrate on agents not capable of controlling their own movement, e.g. the ones designed to be carried around. Their environment comprises of a user and the physical reality whose nature is continuous rather than discrete. An approach to modelling of such systems is presented. The approach, which is based on the DisCo method, takes into account the continuous nature of the environment. Joint actions and closed system modelling are used to coordinate multi-agent interactions at a high level of abstraction. An example is presented where the approach is illustrated by a specification modelling file transfer operation between two agents.