Section: New Results
Component Models and Foundations
Program equivalences in higher-order calculi
Much progress has been accomplished in 2008 in the study of higher-order calculi as models of component-based programs. During Alan Schmitt's sabbatical leave at University of Bologna, the collaboration with Davide Sangiorgi and several of his students resulted in the design of a core higher-order calculus that is rich enough to be Turing complete, yet fundamental enough to have a decidable notion of program equivalence. This work was presented at the LICS international conference  .
In parallel, we have continued to investigate the impact of the addition of a passivation operator, required to faithfully model live-cycle properties of components, to the proof of program equivalence. We have showed that the interaction of passivation and restriction prevents the efficient testing of program equivalence  , and very recently discovered a proof technique, called complementary bisimulation, to characterize program equivalence  for higher-order process calculi with passivation and restriction. Both of these results are currently submitted for publication.
We have also developed a formal specification of the Fractal component model using the Alloy specification language  . The specification covers all the elements of the informal Fractal specification, it lifts all the ambiguities of the informal specification, and it provides a truly programming-language independent specification of the Fractal model in first-order relational logic. This work constitute a basis for ongoing developments towards a formalization of the Fractal architecture description language.