Big Metamodels Are Evil - Package Unmerge - A Technique for Downsizing Metamodels.

While reuse is typically considered a good practice, it may also lead to keeping irrelevant concerns in derived elements. For instance, new metamodels are usually built upon existing metamodels using additive techniques such as profiling and package merge. With such additive techniques, new metamodels tend to become bigger and bigger, which leads to harmful overheads of complexity for both tool builders and users. In this paper, we introduce "package unmerge" - a proposal for a subtractive relation between packages - which complements existing metamodel-extension techniques.