Overview of Patent Retrieval Task at NTCIR-4

We describe the overview of patent re-trieval task at NTCIR-3. The main task was the technical survey task, where participants tried to retrieve relevant patents to news ar-ticles. In this paper, we introduce the task design, the patent collections, the character-istics of the submitted systems, and the re-sults overview. We also arranged the free-styled task, where participants could try anything they want as far as the patent col-lections were used. We describe the brief summaries of the proposals submitted to the free-styled task.