FACET AND PRISM BASED MODEL FOR PEDAGOGICAL INDEXATION OF TEXTS FOR LANGUAGE LEARNING - The Consequences of the Notion of Pedagogical Context Topics: Algorithms and Data Structures; Data and Information Retrieval; Media Search and Retrieval; Natural Language Processing; Software Architectures In Proceedings of the 5th International Conference on Software and Data Technologies - Volume 2: ICSOFT, 413-422, 2010 , University of Piraeus, Greece