M.: A manifesto for model merging

If a modeling task is distributed, it will frequently be nec-essary to merge models developed by different team mem-bers. Existing approaches to model merging make assump-tions about the types of model to be merged, and the na-ture of the relationship between them. This makes it hard to compare approaches. In this paper, we present a manifesto for research on model merging. We propose a framework for comparing different approaches to merging, by treating merge as an algebraic operator over models and model re-lationships. We specify the algebraic properties of an ide-alized merge operator, as well as related operators such as match, diff, split, and slice. We then show how our frame-work can be used to compare existing approaches by apply-ing it to two of our own research projects on model merging. We show how this analysis permits a detailed comparison of approaches, reveals the key features of each, and identifies weaknesses that require further research. Most importantly, the framework emphasizes the need to make explicit all as-sumptions about the relationships between models, and in-deed to treat model relationships as first class objects.