Date Added: Dec 2010
In order to solve the low efficiency problem of directly querying single node probability in the set of all ordinary XML data obtained by enumerating possible world set of the corresponding probabilistic XML data, the method is presented that probabilistic XML data of possible world set is represented by semis-structured information unit. And it is modeled probabilistic XML data tree. Then the rules of decomposing probabilistic XML tree of possible world model are discussed. An algorithm for decomposing the probabilistic XML tree according to the normal form is also presented.