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Changes as First-Class Citizens

Software must evolve to keep up with an ever-changing context, the real world. We discuss an emergent trend in software evolution research revolving around the central notion that drives evolution: Change. By reifying change, and by modelling it as a first-class entity, researchers can now analyse the complex phenomenon known as software evolution with an unprecedented degree of accuracy. We present a Systematic Mapping Study of 86 articles to give an overview on the state of the art in this area of research and present a roadmap with open issues and future directions.