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Expired Canadian patentCanada

Computer aided document retrieval

CA 2540241 C · Owner: St. Petersburg State University · Inventors: Patterson, David; Dobrynin, Vladimir

CIPO record

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Abstract From the Canadian patent

A method of determining cluster attractors for a plurality of documents comprising at least one term. The method comprises calculating in respect of , each term, a probability distribution indicative of the frequency of occurrence of the, or each, other term that co-occurs with said term in at least one of said documents. Then, the entropy of the respective probability distribution is calculated. Finally, at least one of said probability distributions is selected as a cluster attractor depending on the respective entropy value. The method facilitates very small clusters to be formed enabling more focused retrieval during a document search.

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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.

Why it's free to use

  • Filed September 27, 2004 and granted September 17, 2013. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended September 27, 2024.
  • A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by September 27, 2026.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledSeptember 27, 2004
GrantedSeptember 17, 2013
Term endedSeptember 27, 2024
Patent numberCA 2540241 C
Classification (IPC)—

Timeline

Timeline From CIPO dates

2005200720092011201320152017201920212023Application filedSep 27, 2004Patent grantedSep 17, 2013Term endedSep 27, 2024

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Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.