Extending the product family approach to support n-dimensional and hierarchical product lines

The software product-line approach (for software product families) is one of the success stories of software reuse. When applied, it can result in cost savings and increases in productivity. In addition, in safety-critical systems the approach has the potential for reuse of analysis and testing results, which can lead to safer systems. Nevertheless, there are times when it seems like a product family approach should work when, in fact, there are difficulties in properly defining the boundaries of the product family. The authors draw on their experiences in applying the software product-line approach to a family of mobile robots as well as case studies done by others to: (1) illustrate how domain structure can currently limit applicability of product-line approaches to certain domains, and (2) demonstrate our initial progress towards a solution using a set-theoretic approach to reason about domains of what we call n-dimensional and hierarchical product families.