Test Collections for Patent-to-Patent Retrieval and Patent Map   Generation in NTCIR-4 Workshop
  This paper describes the Patent Retrieval Task in the Fourth NTCIR Workshop, and the test collections produced in this task. We perform the invalidity search task, in which each participant group searches a patent collection for the patents that can invalidate the demand in an existing claim. We also perform the automatic patent map generation task, in which the patents associated with a specific topic are organized in a multi-dimensional matrix. 
Atsushi Fujii, Makoto Iwayama, and Noriko Kando