HawkEye: User-Guided Enumeration of Scenarios

Abstract

Writing declarative models has numerous benefits, ranging from automated reasoning and correction of design-level properties before systems are built, to automated testing and debugging of their implementations after they are built. Alloy is a declarative modeling language that is well suited for verifying object-oriented designs. A key strength of Alloy is its scenario-finding toolset the Analyzer, which outputs all valid scenarios that adhere to the model's constraints up to a user-provided scope. However, in order for scenario-finding toolsets to be useful and not an undue burden, scenario-finding toolsets need to generate a relatively small but valuable collection of scenarios. This paper outlines Hawkeye, a novel interactive enumeration technique for the Analyzer that empowers the user to select which elements of a scenario the user wants to keep the same or differ in the next enumeration. Experimental results show that our technique can modify scenario enumeration without significant overhead on the size and complexity of the underlying SAT problem. Moreover, we highlight Hawkeye's ability to help users explore faulty models. Hawkeye is available at: https://github.com/alloy-hawkeye/Hawkeye.git