Computation of Summaries Using Net Unfoldings

We study the following summarization problem: given a parallel composition A=A1||...||An of labelled transition systems communicating with the environment through a distinguished component Ai, efficiently compute a summary Si such that E||A and E||Si are trace-equivalent for every environment E. While Si can be computed using elementary automata theory, the resulting algorithm suffers from the state-explosion problem. We present a new, simple but subtle algorithm based on net unfoldings, a partial-order semantics, give some experimental results using an implementation on top of MOLE, and show that our algorithm can handle divergences and compute weighted summaries with minor modifications.