Certain and possible XPath answers

Sara Cohen*, Yaacov Y. Weiss

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

8 Scopus citations


Formulating an XPath query over an XML document is a difficult chore for a non-expert user. This paper introduces a novel approach to ease the querying process. Instead of specifying a query, the user simply marks positive examples X+ of nodes that fit her information need. She may also mark negative examples X- of undesirable nodes. A deductive method, to suggest additional nodes that will interest the user, is developed in this paper. To be precise, a node y is a certain answer if every query returning all positive examples X+, and not returning any negative example from X -, must also return y. Similarly, y is a possible answer if there exists a query returning X+ and y, while not returning any node in X-. Thus, y is likely to be of interest to the user if y is a certain answer, and unlikely to be of interest if y is not even a possible answer. The complexity of finding certain and possible answers, with respect to various classes of XPath, is studied. It is shown that for a wide variety of XPath queries (including child and descendant axes, wildcards, branching and attribute constraints), certain and possible answers can be found efficiently, provided that X+ and X- are of bounded size. To prove this result a novel algorithm is developed.

Original languageAmerican English
Title of host publicationICDT 2013 - 16th International Conference on Database Theory, Proceedings
Number of pages12
StatePublished - 2013
Event16th International Conference on Database Theory, ICDT 2013 - Genoa, Italy
Duration: 18 Mar 201322 Mar 2013

Publication series

NameACM International Conference Proceeding Series


Conference16th International Conference on Database Theory, ICDT 2013


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