Patent Document ID: 9384287
Application ID: 14156093

Base Claim:
1. A method comprising: receiving, by a processing device, data representing a plurality of corpora, each of the plurality of corpora including a set of documents; receiving, by a processing device, data representing terms that appear in the corpora; for each one of the terms, determining, by a processing device, a plurality of inverse document frequency values each associated with a respective one of the plurality of corpora; receiving, by a processing device, data representing a subset of the terms that also appear in a document; for each term in the subset of the terms, determining, by a processing device, a term frequency for the term in the document; for each term in the subset of the terms, determining, by a processing device, an augmented term frequency-inverse document frequency value based on: (i) the term frequency, and (ii) the plurality of inverse document frequency values that were determined for the term in the subset of the terms; and for each term in the subset of the terms that also appear in the document, selecting, by a processing device, as a combined inverse document frequency value, a minimum value of a plurality of normalized inverse document frequency values determined for the term in the subset of the terms.

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Claim 4:
4. The method of claim 1 , further comprising, for each one of the plurality of corpora, determining, by a processing device, a normalization factor based on a subset of the inverse document frequency values associated with the one of the plurality of corpora and a set of reference inverse document frequency values.