ABSTRACT
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The problem of answering query using views is to find efficient methods
of answering a query using a set of previously materialized views over the 
database, rather than accessing the database. This problem has been 
extensively studied in the relational world. In contrast, it has 
relatively little attention in the area of XML. Since this problem is 
relevant to a wide varities of data management problems, there is a
pressing needs to develop more techniques to solve it for XML effectively 
and efficiently.

We study a class of XPath queries and materialized views which may contain
child, descendant axis and predicates. We first describe an algorithm to 
find the maximally-contained rewritings in the absence of database schema. 
We then present an efficient algorithm to search the maximally-contained
rewriting under acyclic schema and prove the uniqueness of rewriting. 
Finally we show its performance experimentally by extending our algorithm
to answer queries in XQuery expression.