Progress of the research of information retrieval models in the 80's: A critical review

In the research field of information retrieval(IR) models, there were many activities of research and development in the 80's. This paper reviews articles primarily concerned with IR models, especially which take quantitative approaches, for the purpose of tracing the progress in the research field critically. The number of those articles are too many to review comprehensively in this paper, so the author chose a subset of such articles written in Japanese or English. This paper, first of all, describes some basic problems of conventional IR systems based on Boolean model. Secondly, it reviews several specific models in the following order: vector space model, fuzzy set model, probabilistic model, integrated model, and other retrieval models. Finally, it concludes that the progress of the field in the 80's can be summarized as continuation and refinement of the results of the research activities in the 60's and 70's, and that we cannot get any results which make a radical change in the framework of the research field. However, this paper also concludes that many useful, interesting results were produced in the same decade, and it suggests directions for further research which will bring fruitful results in the next decade.