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an XML focument.
In the current status of the implementation, a medi-
ator “discovers” an other mediator using a static medi-
ator address list. More complex and dynamic discov-
ery techniques will be supported in the coming ver-
sions. Moreover, we deliberately ignored the search
of the actual individuals (ABox) that satisfy a query,
i.e. in the current work, we only consider TBoxes.
4 CONCLUSION
In this paper, we presented a method and an algo-
rithm for testing the subsumption relationship, deter-
mining concept complements and finding composite
answers. Some service of subsumption test and de-
termine Complement has been implemented in Java,
that is based on a normalization-comparison algo-
rithm and we can access these services by Web. One
of the originality of this work is in the type of query
answering we provide and also in the way we used
and implemented the complement concept. Indeed, to
the best of our knowledge, using the complement con-
cept for query answers composition does not figure
in the literature we had in hands nor in systems that
implement DLs, like RACER (Haaslev and Moller,
2003) one of the most representative DL system.
Future work may consider the complexity of the
algorithm, and the cooperation of mediators in het-
erogeneous environments, i.e. environments where
mediators’ knowledge bases are described in differ-
ent languages.
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