Systems, methods, and software for classifying documents

To reduce cost and improve accuracy, the inventors devised systems, methods, and software to aid classification of text, such as headnotes and other documents, to target 5 classes in a target classification system. For example, one method comprises: identifying a first set of noun-word pairs in the input text, with the first set including at least one noun-word pair formed from a noun and non-adjacent word in the input text; identifying two or more second sets of noun-word pairs, with each second set including at least one noun-word pair formed from a noun and non-adjacent word in text 10 associated with a respective one of the target classes; determining a set of scores based on the first and second sets of noun-word pairs; and classifying or recommending classification of the input text to one or more of the target classes based on the set of scores.