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November 2006

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2006-13: Unranked Tree Automata with Sibling Equalities and Disequalities
by Peter Schneider-Kamp 22 Nov '06

22 Nov '06

The following technical report is available from http://aib.informatik.rwth-aachen.de: Unranked Tree Automata with Sibling Equalities and Disequalities Wong Karianto, Christof Löding AIB 2006-13 We propose an extension of the tree automata with constraints between direct subtrees (Bogaert and Tison, 1992) to unranked trees. Our approach uses MSO-formulas to capture the possibility of comparing unboundedly many direct subtrees. Our main result is that the nonemptiness problem for the deterministic automata, as in the ranked setting, is decidable. It turns out that the main difficulty is indeed the absence of the rank, as it gives a certain bound on the number of distinct subtrees needed in order to satisfy an equality or disequality constraint. We overcome this difficulty by finding such a bound via a brute-force method. Keywords: (unranked) tree automata, monadic second-order logic, equality and disequality constraints

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2006-14: Report of the GI Work Group "Requirements Management Tools for Product Line Engineering"
by Peter Schneider-Kamp 14 Nov '06

14 Nov '06

The following technical report is available from http://aib.informatik.rwth-aachen.de: Report of the GI Work Group "Requirements Management Tools for Product Line Engineering" Danilo Beuche, Andreas Birk, Heinrich Dreier, Andreas Fleischmann, Heidi Galle, Gerald Heller, Dirk Janzen, Isabel John, Ramin Tavakoli Kolagari, Thomas von der Maßen, Andreas Wolfram AIB 2006-14 A software product-line-oriented approach to developing systems has an impact on the development process as a whole. All artifacts produced during the process have to be properly managed in order to benefit from a product-line-oriented approach. Although the basic idea of product lines is simple, systematic implementation of the approach is a challenging task. In fact, today's software system families have such complex variability that their handling must be supported by tools, otherwise a systematic approach would not be possible. The same holds for requirements management of software product lines. The technical report presented here analyzes specific scenarios in the context of requirements management and software product lines and derives important requirements that have to be observed if requirements management tools are to be usefully applied to product lines. Current requirements management tools are evaluated on the basis of these requirements. This evaluation revealed that all requirements management tools currently used in industry need to be improved if they are to be successfully used in a product line setting. Nevertheless these tools are used in practice and are also used in product line settings and as the scenarios described in this report show they are also used successfully - but this is only achieved because workarounds are in place: either the tool itself is enhanced or related processes bypass shortcomings of the tool. The result of this report is a comprehensive analysis of requirements and requirements management tools in the context of software product lines based on practical experience.

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