Although extracting information from tables is essential for Internet information agents, most tables are designed for human eyes and their layout and semantic meanings are not well defined. In practice, encoding the layout of each information source is impossible. This work presents a novel semantic search approach capable of extracting information from general tables. Semantic ontology allows our agents to read tables in the same knowledge domain with different layouts. In addition, a system of layout syntax and a set of transformation rules are defined to transform tables into databases without losing their semantic meanings.

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A method for automatic generation of optimized 3-axis nc programs for pocketing operations is described that relies on the use of boundary files for geometric and topological information about the workpiece. A boundary file of the part is first created by a solids modeller and then input to the system along with machining parameters. After the user indicates those areas of the part to be machined, a cutter path of minimum length is generated consisting of two cut-sequences: a rough-cut and a finishing-cut. To implement the procedure, an APT code generator has been developed and tested on several parts.

A system has been developed for verification of multiaxis NC programs with dynamic display of the in-process part in real-time. Such a system is needed because it is time-consuming and expensive to verify an NC program for machining a complicated part. Based on the concept of solid modeling, this system models a "machined" part by taking the Boolean difference of the tool swept volumes from the workpiece. Two key features contribute to the real-time performance of the system: an analytical method for computing swept volumes, and a scan-rendering algorithm for displaying images of solid models. Experience from implementing the system for industrial applications will be discussed. Also presented is a practical method for verifying NC programs with positional tolerances.

This paper presents a theorem relating the geometry of two smooth surfaces with the topology of their intersection. Algorithms for computing intersections of surfaces are very basic to those solid-modeling systems that allow Boolean operations such as Union, Intersection, and Subtraction on solids. Recently, such an algorithm based on recursive subdivision of the surfaces has attracted a lot of attention because of its simplicity and wide applicability. However, this algorithm for intersection of surfaces fails to find all intersections for certain relative orientations of surfaces. Finer subdivision of the surfaces may result in the correct intersections but also results in many unnecessary computations. The mathematical result established in this paper is significant in that it provides a check to determine when finer subdivision will yield no new topological information for an intersection. It is shown how the check may be incorporated into the existing subdivision algorithm to compute intersections reliably and efficiently.