1. A computer-implemented method for probabilistically quantifying a degree of relevance between a first document and a second document citationally related to said first document, the method comprising: determining one or more generational citation counts between said first and second documents at generations higher than a first generation citational relationship; and applying a probability transform function to said one or more determined generational citation counts to determine a relevance score reflecting a degree to which the first and second documents are related, said probability transform function being selected and optimized to substantially estimate a relative event probability that said first document cites said second document or said second document cites said first document.