Exploiting Modal Logic to Express Performance Measures

Abstract. Stochastic process algebras such as PEPA provide ample support for the component-based construction of models. Tools compute the numerical solution of these models; however, the stochastic process algebra methodology has lacked support for the specification and calculation of complex performance measures. In this paper we present a stochastic modal logic which can aid the construction of a reward structure over the model. We discuss its relationship to the underlying theory of PEPA. We also present a performance specification language which supports high level reasoning about PEPA models, and allows queries about their equilibrium behaviour. The meaning of the specification language has its foundations in the stochastic modal logic. We describe the implementation of the logic within the PEPA Workbench and a case study is presented to illustrate the approach.

Trust domains in system models: algebra, logic, utility, and combinators

Understanding the boundaries of trust is a key aspect of accurately modelling multi-agent systems with heterogeneous motivating factors. Reasoning about these boundaries in highly interconnected, information-rich ecosystems is complex, and dependent upon modelling at the correct level of abstraction. Building on an established mathematical framework, which incorporates both logical and cost-based descriptions of systems, and a formal characterization of trust domains in terms of the above, we develop techniques for the combination and substitution of trust domains