Mining specifications using nested words

Parameter mining of traces identifies formal properties that describe a program's dynamic behaviour. These properties are useful for developers to understand programs, to identify defects, and, in general, to reason about them. The dynamic behavior of programs typically follows a distinct pattern of calls and returns. Prior work uses general logic to identify properties from a given set of templates. Consequently, either the properties are inadequate since the logic is not expressive enough, or the approach fails to scale due to the generality of the logic. This paper uses nested words and nested word automata that are especially well suited for describing the dynamic behaviour of a program. Specifically, these nested words can describe pre/post conditions and inter-procedural data-flow and have constant memory requirements. We propose a framework for mining properties that are in the form of nested words from system traces. As a part of the framework, we propose a novel scalable algorithm optimized for mining nested words. The framework is evaluated on traces from real world applications.