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
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.