1. A method comprising: identifying partial subtrees of a tree, said tree comprising hierarchical data representing one or more XML documents, said partial subtrees having depths up to a predetermined depth defining a longest separation between a root node and terminal node of said partial subtrees; enumerating rooted partial subtrees of at least one of said identified partial subtrees; representing said tree as one or more electrical digital signals representing one or more target numerals, said one or more target numerals being associated with said enumerated rooted partial subtrees according to an association between trees and numerals; determining one or more signals representing a probe numeral representing a query to said one or more XML documents based, at least in part, on one or more electrical digital signals representing a probe tree, said probe tree comprising a piece of information of interest; and comparing, using a processor, said one or more electrical digital signals representing said probe numeral with said one or more signals representing said one or more target numerals to detect a presence of said piece of information in said tree by detecting a presence of said one or more signals representing said probe tree in one or more electrical digital signals representing said tree based, at least in part, on a match of said one or more signals representing said probe numeral with one or more electrical digital signals representing at least one of said target numerals.