Boolean retrieval systems have been most widely used among commercially available information retrieval systems. This is because uers are able to express their information need more conviniently and briefly by using a Boolean query formulation.
But, ...
Boolean retrieval systems have been most widely used among commercially available information retrieval systems. This is because uers are able to express their information need more conviniently and briefly by using a Boolean query formulation.
But, Boolean retrieval systems have some disadvanteges. First, document ranking is amenable because various similarity coefficients cannot be computed between queries and documents. Second, it cannot retrieve partially related documents because of the nature of Boolean operators.
Among the many retrieval techniques that have been developed to compensate for these weaknesses of Boolean retrieval, the fuzzy set model can solve the above defects. Fuzzy set theory generalizes traditional set theory by permitting partial membership in a set and makes it possible to recognize different degree to which a document can match a request.
This study compared the retrieval effectiveness of Boolean and fuzzy set retrieval strategies through a retrieval experiment. Recall and precision ratio was used to evaluate effectiveness of fuzzy set retrieval strategies. The fuzzy information retrieval system was designed for this experiment. This designed system has three modules-automatic indexing, keyword connection matrix construction, and fuzzy set retrieval modules. Experimental data consisted of 207 index terms, selected from 135 articles in library and information science journals containing Korean abstracts. Eight search queries were used for this retrieval experiment.
The results of this experiment are as follows.
(1) The precision ratio of fuzzy set retrieval is 63%, higher than the 52% of Boolean retrieval. On the other hand, the recall ratio of fuzzy set retrieval is 75%, a little bit lower than the 72% of Boolean retrieval.
(2) In Boolean retrieval systems, any relevant document which has 'and not' operator search terms as index terms cannot be retrieved. But, in fuzzy retrieval systems, these kinds of relevant documents can be retrieved.
(3) In order to improve the ratio of recall and precision of designed fuzzy retrieval system, the learning algorithm, which modifies the initial relation value of keyword connection matrix by using subject specialist's feedback, have to be devised and included in the system.