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Item A Compositional Semantics for Graphics(Eurographics Association, 1988) Pineda, Luis A.In this paper a theory for developing "intelligent" interactive graphic systems is detailed. The Fregean compositionality principle is enunciated for graphical representations. Geometrical symbols and relations receive semantic interpretations which are expressed as first order relations in the first order logical language. These interpretations are introduced with the help of deictic expressions. Deictic expressions constitute one associative mechanism between analogical representational systems used in graphics, and functional representational systems commonly used in AI applications. Interpretations of graphical symbols and geometrical relations between them constitute an ontology upon which complex linguistic interpretations are assigned to graphics. A concept of graphical grammar is introduced. Frege's compositionality principle, and the notion of graphical grammar lead to a concept of meaningful drawing. The graphical grammar constitutes a second associative mechanism between the two representational systems that have been mentioned. The truth conditions for relations in the graphical grammar are computed through geometrical knowledge. Computational geometry algorithms are associated with the high level representational system by means of the graphical grammar. Semantic interpretations of graphics are useful in carrying out natural language-like dialogue about graphical representations. Dialogues refer to true facts in particular interactive states, A notion of interactive state as a function of time and situation is then developed. One example of how this theory can be used in linking interactive graphics with AI applications is given. In the example, the semantic interpretation of a geographical map is constructed. This theory has been tested with an experimental program called GRAFLOG. The program is implemented in PROLOG and GKS.Item GRAFLOG: Understanding Drawings through Natural Language(Blackwell Publishing Ltd and the Eurographics Association, 1988) Pineda, Luis A.; Klein, Ewan; Lee, JohnThis paper describes an experimental interactive graphics interface, GRAFLOG, in which drawings receive linguistic interpretations. It is possible to emulate linguistic interaction in situations where graphics is thought to be necessary. The paper presents examples of such a kind of dialogue and the architecture of the implementation. The paper explains how representations of drawings can be constructed by treating graphical symbols as"objects", and how a parallel linguistic interpretation for these symbols can be constructed. It highlights the relevance of"deictic expressions" and"spatial prepositions" in building the interface mechanisms between these two kinds of representations. Lastly, it shows how a reasoning component is constructed for making deductions from premises that are found in both the graphical and linguistic domains. Using GRAFLOG, it is possible to represent knowledge through words and pictures. GRAFLOG is implemented, using an object oriented programming style, in PROLOG and GKS.Item Reference, Synthesis and Constraint Satisfaction*(Blackwell Science Ltd and the Eurographics Association, 1992) Pineda, Luis A.In this paper we discuss two kinds of constraint satisfaction problems that arise in the context of geometric modelling, In particular in the modification of 2-D wire-frame diagrams that are subject to an arbitrary number of geometrical and topological constraints. We argue that problems in this domain can be classified in two categories that we shall call problems of reference and problems of synthesis. Since Sutherland s Sketchpad program [16], a large number of systems have addressed constraint satisfaction in terms of the representation of constraints sets as equation systems, which in turn are solved by numerical methods like local propagation, relaxation and Gaussian elimination. Here, we present an alternative framework. We argue that conceptualising constraint satisfaction as symbolic rather than"numerical" problems helps to clarify the notion of"constraint", simplify solution methods, and to explain the intuitive inferential processes underlying the modification of drawings in the course of interactive drafting sessions. The theory presented in this paper has been tested with an experimental computer program called Graflog [5, 8, 9, 10, 11, 12]. The program has been implemented during the last four years, and has evolved through several stages. The current version is implemented in terms of two Unix-processes connected by Unix-pipes. The first is a"C" program running X windows, and handles the external aspects of the interaction. The second is a Prolog program supporting the representational structures and interpreters of the system.