Advisors:

Software maintenance is the main driver of total costs in the lifecycle of long-living software systems. Code clones, that is, the replication of code fragments across the system, decrease maintainability: It increases the code size and hinders manual code change, inspection, and analysis. Intensive research has been spent in the last two decades to determine the nature of clones, specifically why and where they occur as well as whether they impair the maintenance of software systems. While recent studies expressed doubt on the general harmfulness of clones, it is commonly accepted that the awareness of existing code clones in software system is indispensable in any case. Recently, software product line engineering gained momentum since it provides a sys-tematic approach for reuse amongst a set of similar programs, commonly referred to as software product lines (SPL). An SPL allows the programmer to manage a set of pro-grams by describing variabilities and commonalities between them in terms of features. In this context, a feature is an increment in end-user visible functionality. As a result, a particular program can be derived by selecting the desired features and subsequentl