The Notion of H-IFS: An Approach for Enhancing the OLAP Capabilities in Oracle10g Panagiotis Chountas, 1,∗ Ermir Rogova, 1 Krassimir Atanassov 2,† 1 DKMG—ECS, University of Westminster, London, W1W 6OW, UK 2 CLBME, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria Query answering requirements for a knowledge-based treatment of user requests led us to intro- duce the concept of closure of an intuitionistic fuzzy set over a universe that has a hierarchical structure. We recommend the automatic analysis of queries according to concepts defined as part of knowledge-based hierarchies to guide the query answering as part of an integrated database environment with the aid of hierarchical intuitionistic fuzzy sets (H-IFS). In this paper based on the notion of H-IFS, we propose an ad hoc utility build on top of Oracle10g that allows us to enhance the query capabilities of by providing better, knowledgeable, and optimized answers to user’s requests. C  2010 Wiley Periodicals, Inc. 1. INTRODUCTION In 1970s, the need for flexible models and query languages to manage the ill-defined nature of information in databases was identified. 1 Over the past years, we have witnessed an increasing interest in expressing user or domain preferences 2 inside database queries. First, it appeared to be a desirable property of a query system to offer more expressive query languages that can be more faithful to what a user intends to say. Second, a classical query in the sense of a relational paradigm may also have a restricted answer or sometimes an empty set of answers, whereas a relaxed version of the query enhanced with background or domain knowledge might be matched by some items in the database. Nowadays, the application of online analytical processing (OLAP) technology to other knowledge fields, e.g., medical data and the use of semistructured sources, e.g., extensible markup language (XML), and nonstructured sources has made these requirements even more important Frequently integrated database management systems (DBMSs) contain incom- plete data, which we may represent using hierarchical background knowledge to ∗ Author to whom all correspondence should be addressed: e-mail: chountp@wmin.ac.uk. † e-mail: krat@argo.bas.bg. INTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, VOL. 26, 262–283 (2011) C  2010 Wiley Periodicals, Inc. View this article online at wileyonlinelibrary.com. • DOI 10.1002/int.20466