N-way model merging

Model merging is widely recognized as an essential step in a variety of software development activities. During the process of combining a set of related products into a product line or consolidating model views of multiple stakeholders, we need to merge multiple input models into one; yet, most of the existing approaches are applicable to merging only two models. In this paper, we define the n-way merge problem. We show that it can be reduced to the known and widely studied NP-hard problem of weighted set packing. Yet, the approximation solutions for that problem do not scale for real-sized software models. We thus evaluate alternative approaches of merging models that incrementally process input models in small subsets and propose our own algorithm that considerably improves precision over such approaches without sacrificing performance.