Abstraction Modulo Stability for Reverse Engineering

The analysis of legacy systems requires the automated extraction of high-level specifications. We propose a framework, called Abstraction Modulo Stability, for the analysis of transition systems operating in stable states, and responding with run-to-completion transactions to external stimuli. The abstraction captures the effects of external stimuli on the system state, and describes it in the form of a finite state machine. This approach is parametric on a set of predicates of interest and the definition of stability. We consider some possible stability definitions which yield different practically relevant abstractions, and propose a parametric algorithm for abstraction computation. The obtained FSM is extended with guards and effects on a given set of variables of interest. The framework is evaluated in terms of expressivity and adequacy within an industrial project with the Italian Railway Network, on reverse engineering tasks of relay-based interlocking circuits to extract specifications for a computer-based reimplementation.