A multimedia user preference model that supports semantics and its application to MPEG 7/21A multimedia user preference model that supports semantics and its application to MPEG 7/21 Πλήρης Δημοσίευση σε Συνέδριο Conference Full Paper 2015-10-042006enSemantic interoperability is usually provided in open environments through standards and domain ontologies. The dominant standards for multimedia content and service descriptions are MPEG-7 and MPEG- 21. The MPEG-7 Semantic DS has powerful semantic description capabilities and supports using semantic entities specified in domain ontologies in multimedia content descriptions. However, the MPEG-7/21 Usage Environment allows neither the specification of semantic user preferences nor the exploitation of domain knowledge and MPEG-7 semantic metadata descriptions. In addition, the users cannot explicitly specify, in the hierarchical MPEG-7/21 filtering and search preferences, the boolean operators that should be used during content filtering to combine the hierarchy components. We think these as serious limitations and we propose a hierarchical semantic user preference model that allows for the explicit specification of boolean operators. Then, we present the application of the model in MPEG-7/21 and the model implementation within the DS-MIRF framework.http://creativecommons.org/licenses/by/4.0/35-42In the proceedings of the Multimedia Modeling Chrisa Tsinaraki IEEE The MPEG-7/21 Usage Environment