1. A method for estimating the similarity between at least two portions of text including the steps of: forming a set of syntactic tuples, each tuple including at least two terms and a relation between the two terms; classifying the relation between the terms in the tuples according to a predefined set of relations; establishing the relative agreement between syntactic tuples from the portions of text under comparison according to predefined classes of agreement; calculating a value representative of the similarity between the portions of text for each of the classes of agreement; and establishing a value for the similarity between the portions of text by calculating a weighted sum of the values representative of the similarity between the portions of text for each of the classes of agreement.