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An algebra which operates on partitioned relations is developed. Relation partitioning is achieved by defining equivalence relations on n-ary relations. It is shown that the algebra is as powerful as the original relational algebra, having the advantage of a set-processing capability. This feature provides both greater flexibility in query specification and(More)
Schema matching is a fundamental issue in many database applications , such as query mediation and data warehousing. It becomes a challenge when different vocabularies are used to refer to the same real-world concepts. In this context, a convenient approach, sometimes called extensional, instance-based or semantic, is to detect how the same real world(More)
A key issue in interactive storytelling is how to generate stories which are, at the same time, interesting and coherent. On the one hand, it is desirable to provide means for the user to intervene in the story. But, on the other hand, it is necessary to guarantee that user intervention will not introduce events that violate the rules of the intended genre.(More)
Quests are a fundamental storytelling mechanism used by computer role-playing games to engage players in the game's narrative. Although role-playing games have evolved in many different ways in the last years, their basic narrative structure is still based on static plots manually created by game designers. In this paper, we present a method for the(More)
A database description framework is introduced that accounts for static constraints, that is, constraints on what data can be stored,as well as transition constraints, that is, constraints on how data can be updated. Two levels of specification are considered. At the first level of specification, a database description Dl does not indicate how the database(More)
Research on database design at PUC-Rio dates back to the late seventies and covers a broad range of topics, from the early development of the relational model to recent applications of semiotic concepts to the design and specification of information systems. This paper briefly reviews some of the major contributions of the group, from the perspective of the(More)
A key issue in interactive storytelling is how to generate stories which are, at the same time, interesting and coherent. On the one hand, it is desirable to provide means for the user to intervene in the story. On the other hand, it is necessary to guarantee that user intervention will not introduce events that violate the rules of the intended genre. This(More)