Semantic query optimization is comparatively a recent approach for the transformation of given query into equivalent alternative queries using matching rules in order to select an optimal query based on the costs of executing alternative queries. There is the potential to reduce query execution cost by applying this process in a multi-database system. In such an environment, rules can be classified into three types: global, inter-schema and local. In this paper, a systematic method is proposed for inducing global rules from holding rules in local databases with the consideration of schema conflicts.
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