“…Starting from a set of "anchor points" which indicate corresponding elements, the key idea is to extract the common parts in a step-wise manner through a series of variantpreserving refactorings [29,43,51,68,[71][72][73][74][75][76]. Anchor points may be determined through clone detection [43,[72][73][74] or conventional matchers [29,51,71,75,76], and may be corrected and improved by the merge refactoring. However, such implicit calculations of optimized n-way matchings require extensive catalogues of language-specific refactoring operations which have to be specified manually [51,[73][74][75].…”