Patent ID: 6883135

Claim:
A computer-implemented method for selectively accessing a document in response to a current retrieval request, the document being identified by a document address specification, the document having been retrieved during a previous retrieval request, the method comprising: determining whether to access the document during the current retrieval request by identifying with the aid of a statistical model whether the document is likely to have changed since a previous retrieval request; and accessing the document if the determination produces an instruction indicative that the document at the document address specification should be accessed during the current retrieval request, wherein determining whether to access the document during the current retrieval request comprises computing a probability that the document is likely to have changed since a previous retrieval request, and further wherein computing the probability that the document is likely to have changed since a previous retrieval request comprises: selecting an active probability indicative of a proportion of documents in a plurality of documents that are changing at various change rates, the plurality of documents including the document, training the active probability to reflect an experience with the document during a plurality of previous document retrieval requests, and using the trained active probability to compute the probability that the document has changed since a previous retrieval request.