Approximate structural matching over ordered XML documents

There is an increasing need for an XML query engine that not only searches for exact matches to a query but also returns "query-like" structures. We have designed and developed XFinder, an efficient top K tree pattern query evaluation system, which reduces the problem of approximate tree structural matching to a simpler problem of subsequence matching. However, since not all subsequences correspond to valid tree structures, it is expensive to enumerate common subsequences between XML data and query and then filter the invalid ones. XFinder addresses this challenge by detecting and pruning structurally irrelevant subsequence matches as early as possible. Experiments show the efficiency of XFinder on various data and query sets.