XML Querying Based on Extended Path Expressions

XML querying is being actively studied and several models and algorithms have been put forward Makoto Murata put forward a XML query language based on extended path expressions, and also advanced an algorithm for query computation based on hedge automata and string automata Extended path expressions have the advantage over path expressions in that they make full use of the orderliness of XML documents Moreover, extended path expressions are more expressive than the path expressions and can express any query as MSO can do So extended path expressions have been a major theory framework for the study of XML querying Extended path expression, however, are too complex to program in most cases, which leads to higher time complexity of the algorithm Extended path expressions are made simpler and more flexible by introducing wildcard into them, and the time complexity of the algorithm is also reduced by putting forward a new kind of automata, namely automata with a stop set