Empty versus overabundant answers to flexible relational queries

When retrieving and searching desired data over large databases accessible in the web, users might be confronted with two common problems: overabundant answers and empty answers. In the former, the user is provided with an avalanche of responses that satisfy his/her query, while in the latter, no data are returned to the query asked. In this paper, we attempt to address those problems in the context of flexible queries. The basic idea behind the solutions proposed consists in modulating the fuzzy conditions involved in the user query by applying appropriate transformations. According to the problem at hand, this operation leads to a relaxation or an intensification of the user query. Two particular transformations that rely on a convenient parameterized proximity relation are introduced. The predicates of the modified queries are obtained by means of fuzzy arithmetic. The main properties of our proposal are investigated and a comparison with other approaches is outlined.