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Drawing of penetrating lines using personal computer

A program for drawing of penetrating lines was developed in personal computer. PROLOG, a language of Artificial Intelligence, was used and a data structure using relational data base was designed. An algorithm for finding the penetrating lines in the real space was developed. The program can be applied at any types of penetrating problems like curve-surface, surface-surface, curve-object, surface-object, object-object, etc. In developing the program, the following results were obtained. (1) Relational data base built in PROLOG and the function of backtracking are helpful in Computer Graphics. (2) In spite of increasing the number of edges, assigning direction to the edges makes it possible to represent the polygon meshes as the non ordered sets of directional half edges. (3) Topologicaly the penetrating lines of a polygon can be represented as the edge-pairs in the edge list of the polygon,