Empir Software Eng DOI 10.1007/s10664-008-9097-1 EDITORIAL Special issue on information retrieval for program comprehension

Welcome to the special issue on information retrieval for program comprehension (IR4PC). IR4PC employs various interdisciplinary information search techniques to examine the properties of both existing (legacy) and newly created software. IR4PC is important for software reuse, software maintenance and evolution, and reverse engineering, just to mention a few areas. Back in the 1980s and early 1990s, much program comprehension involved representing program code as control and data flow graphs. Recognizing program constructs was performed by comparing flow graphs to a plan library of known constructs (e.g. Rich and Waters 1989). However, formal non-heuristic approaches to program comprehension have been shown to be NP-hard and their success was often illustrated only in toy domains (Woods and Yang 1996). For this reason, heuristic approaches acquired new importance. In the 21st century, much program comprehension research has focused on applying various information retrieval techniques (e.g. text mining, LSI, knowledge-based NL understanding) to software. These new IR4PC semantic measures examine informal information in the tokens within the software itself (e.g. identifier names, function names and variable names, code comments) as well as the natural language content in external documentation such as software requirements documents or software design documents. In the past, IR4PC techniques have been successfully applied to (among other areas) static concept location (using information derived from informal tokens together with structural information such as call graphs to locate code sections that are related to given concepts), to determining whether a particular software component is reusable, to dynamic search or software reconnaissance (examining informal tokens along execution traces of program executed with and without a particular feature), to developer identification (determining which developer is the best one to perform a particular task), to bug locatio