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Spatial relationships are important ingredients for expressing constraints in retrieval systems for spatial databases. In this paper we propose a uniied representation of spatial relationships, 2D Projection Interval Relationships (2D-PIR), that integrates both directional and topological relationships. We propose a graph representation for pictures that is(More)
This paper presents a symbolic formalism for modeling and retrieving video data via the moving objects contained in the video images. The model integrates the representations of individual moving objects in a scene with the time-varying relationships between them by incorporating both the notions of object tracks and temporal sequences of PIRs (projection(More)
In this paper we propose a new model for moving objects, aimed at handling video sequences in mul-timedia databases. The model integrates the representations of individual moving objects and the time-varying relationships between multiple moving objects in a scene. Several new query operators are defined within this model. Some examples illustrating the(More)
In this paper, we describe a prototype image retrieval system for distributed environments based on 2D Projection Interval Relationships (2D-PIR). The system transforms an image to a symbolic representation that describes spatial relationships among objects in the image. The image database consists of three parts: the real image repository (which is(More)
In this paper, the problem of establishing a shared session key in an authenticated way is addressed. New key agreement protocols that support explicit authentication are proposed. The protocols are designed in such a way that permits a trusted third party, such as a firewall, to verify the identities of the parties involved in a key agreement session. This(More)
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