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specific algorithms have both been provided. Besides
the formal and algorithmic approaches, experiments
showed that the annotated tree compressibility, with-
out using any backend compressors is high, on aver-
age approximately 0.4. Finally, a general analysis and
results of testing of compression of entire XML doc-
ument with single instances of vanilla compressors,
compression of annotated tree over markup density,
and compression of annotated transform over com-
pression of XML data were provided, showing the
usefulness of the annotated tree approach.
Simple queries, such as finding all children of a
given node can be efficiently evaluated using the an-
notated trees. Our future work will extend queries to
the subset of XPath expressions known as the core
XPath as defined in (Gottlob et al., 2005), as well as
more sophisticated navigational queries, e.g. asking
for the j-th level-ancestor of u.
ACKNOWLEDGEMENTS
The work of the first and third authors are par-
tially supported by the NSERC RGPIN grant and
NSERC CSG-M (Canada Graduate Scholarship-
Masters) grant respectively.
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