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We study the problem of model checking software product line (SPL) behaviours against temporal properties. This is more difficult than for single systems because an SPL with n features yields up to 2 n individual systems to verify. As each individual verification suffers from state explosion, it is crucial to propose efficient formalisms and heuristics.We recently proposed featured transition systems (FTS), a compact representation for SPL behaviour, and defined algorithms for model checking FTS against linear temporal properties. Although they showed to outperform individual system verifications, they still face a state explosion problem as they enumerate and visit system states one by one.In this paper, we tackle this latter problem by using symbolic representations of the state space. This lead us to consider computation tree logic (CTL) which is supported by the industry-strength symbolic model checker NuSMV. We first lay the foundations for symbolic SPL model checking by defining a feature-oriented version of CTL and its dedicated algorithms. We then describe an implementation that adapts the NuSMV language and tool infrastructure. Finally, we propose theoretical and empirical evaluations of our results. The benchmarks show that for certain properties, our algorithm is over a hundred times faster than model checking each system with the standard algorithm.

International audienceIn the scientific community, feature models are the de-facto standard for representing variability in software product line engineering. This is different from industrial settings where they appear to be used much less frequently. We and other authors found that in a number of cases, they lack concision, naturalness and expressiveness. This is confirmed by industrial experience. When modelling variability, an efficient tool for making models intuitive and concise are feature attributes. Yet, the semantics of feature models with attributes is not well understood and most existing notations do not support them at all. Furthermore, the graphical nature of feature models' syntax also appears to be a barrier to industrial adoption, both psychological and rational. Existing tool support for graphical feature models is lacking or inadequate, and inferior in many regards to tool support for text-based formats. To overcome these shortcomings, we designed TVL, a text-based feature modelling language. In terms of expressiveness, TVL subsumes most existing dialects. The main goal of designing TVL was to provide engineers with a human-readable language with a rich syntax to make modelling easy and models natural, but also with a formal semantics to avoid ambiguity and allow powerful automation

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Abstract. The notion of feature is heavily used in Software Engineering, especially for software product lines. However, this notion appears to be confusing, mixing various aspects of problem and solution. In this paper, we attempt to clarify the notion of feature in the light of Zave and Jackson's framework for Requirements Engineering. By redefining a problem-level feature as a set of related requirements, specifications and domain assumptions-the three types of statements central to Zave and Jackson's framework-we also revisit the notion of feature interaction. This clarification work opens new perspectives on formal description and verification of software product lines. An important benefit of the approach is to enable an early identification of feature interactions taking place in the systems' environment, a notoriously challenging problem. The approach is illustrated through a proof-of-concept prototype tool and applied to a Smart Home example.