Adolfo Guzman

Finding the main themes in a spanish document

Abstract The computer can easily carry out many operations on systematic collections of data when these are numbers: • What are the data about? What are the main topics? • Make a summary. Obtain a summary of May sales of a given store. • Compare. Compare May sales in stores A and B. • Find similarities and discrepancies. How are sales of stores A and B similar? • Find averages. Find the sales in the South of Mexico, in Fall 1997. • Find tendencies. Extrapolate. On the other hand, when data appear in documents in Spanish, organized in sections, paragraphs and sentences, it is not possible for the computer to carry out the above operations. As much of human knowledge is in texts written in natural language, it is convenient to discover methods to carry out those operations. For that, the computer must understand or comprehend the text. This paper shows how to analyze a document containing natural language sentences, so as to recognize its main topics or themes.

Performance of symbolic applications on a parallel architecture

The results of a study of a family of parallel symbolic architectures executing several parallel applications are presented. The class of architectures being simulated is characterized by a shared memory structure, by a hierarchical interconnect, and by clustered processors. Speedup measurements were obtained from six different application kernels. Measurements were also performed to assess the degradation of speedup as a function of the interconnection delays, and to study the effect of different scheduling algorithms. The results presented support the claim that the proposed architecture would be a powerful parallel symbolic computation system. The paper discusses processor starvation, fine grain parallelism, unever loads, foreign reference, schedule and indeterminate computation with respect to the applications chosen.

AHR: a parallel computer for pure Lisp

Parallel processing now constitutes a major direction for computer development, and the future of this field is very bright. At the same time, the field is very difficult due to the complexities inherent in parallel systems. In 1973, these complexities made parallelism seem to be impractical, yet results obtained from a project undertaken that year at the Institute for Research in Applied Mathematics and Systems (IIMAS) at the National University of Mexico demonstrated that parallel systems were more feasible than had previously been assumed.

Enclosing trees

A method is described for representing voxel-based objects by means of enclosing trees. An enclosing tree is a tree which totally covers a voxel-based object, the vertices of the enclosing tree correspond to the vertices of the enclosing surface of the analyzed voxel-based object. An enclosing tree is represented by a chain of base-five digit strings suitably combined by means of parentheses. The enclosing-tree notation is invariant under rotation and translation. Furthermore, using this notation it is possible to obtain the mirror image of any voxel-based object with ease. The enclosing-tree notation preserves the shape of voxel-based objects, allowing us to know some of their topological and geometrical properties. Also, the proposed enclosing-tree notation is a good tool for storing of voxel-based objects.

The effect of application characteristics on performance in a parallel architecture

A shared-memory, hierarchical, clustered architecture is reported. Measurements presented (including speedups) were obtained by running six different symbolic application kernels with varying architectural parameters. The results and graphs shown highlight the manner in which application characteristics place limits on achievable parallel performance, given particular architectural features. The discussion covers processor starvation, fine-grain parallelism, uneven loads, foreign reference, cost scheduling and indeterminate computation with respect to the applications chosen. These measurements provide understanding of some of the interactions that take place between the architectural parameters and the specific applications and suggest ways to improve the architecture. To date, the architecture has shown reasonable speedups on the chosen applications.<<ETX>>

The Conversion Via Software of a SIMD Processor into a MIMD Processor

In this paper a method is described which takes a (pure) Lisp program and automatically decomposes it (automatic parallelization) into several parts, one for each processor of a SIMD architecture. Each of these parts is a different execution flow--a different program--. The execution of these different programs by a SIMD architecture is the main theme of the paper.

Chain coding representation of voxel-based objects with enclosing, edging and intersecting trees

Thrifty methods to represent and store three dimensional objects are important. Two different methods for describing voxel-based objects (VBOs) by means of edging (ETs) and intersecting (ITs) trees are demonstrated. Each tree comes from a different kind of border of the underlying VBO, and both trees are one dimensional alternative descriptors to skeletons for VBOs representation. Vertices in the trees correspond to the vertices of the VBO enclosing surface where some surface vertices have been conveniently suppressed. These descriptors are computed using a base-five digit chain code (combined with parentheses) and has been used to illustrate three dimensional curves and enclosing trees. The descriptors are invariant under rotation and translation, and preserve the VBO shape. Using either descriptor, the description of the mirror image of a VBO is easily obtained. The proposed descriptor notation is a good tool for storing VBOs, and intersecting trees providing further storage savings. Enclosing trees (EcTs) are briefly reviewed as a preamble to introduce ETs and ITs.

The file descriptor: Use of a descriptive tool to retrieve general queries to files

The file descriptor is a data structure that describes or documents the characteristics (position type, initial value, etc.) of the information within a file. Each file containing information possesses a unique file descriptor. The file descriptors for a collection of related files are stored together in a file named DESCRIPTORS. This paper explains the use of the file descriptor for: answering general queries to a file- “retrieve all records satisfying predicate P” This is embodied in a tool called the consultator. a general tool for data input - the capturer - wich allows inputting appropriate data for any file. a tool for report production - the report printer - which allows design of arbitrary output reports. a specification for transformations from several input files into one or more output files - the file transformer - and its corresponding tool (program to interpret such notation). The above tools allow for input, consultation or retrieval, transformations (“computation” or “processing” of data into results) among files, and report generation, all of these without writing programs in high level languages (Pascal, Cobol,...). Instead, we use a simpler description of (a) the screen to be presented for inputting data; (b) the query or predicate; (c) the transformation; (d) the report. The description used in (a) through (d) can be considered as a concise language for specifying data-manipulation (v. gr, administrative or managerial) tasks. If the tools prove to be useful, one can expect considerable savings in the time and effort spent in specifying and programming such data-manipulation tasks. The system in being implemented in Pascal for an IBM-PC network.The file descriptor is a data structure that describes or documents the characteristics (position type, initial value, etc.) of the information within a file. Each file containing information possesses a unique file descriptor. The file descriptors for a collection of related files are stored together in a file named DESCRIPTORS. This paper explains the use of the file descriptor for: answering general queries to a file- “retrieve all records satisfying predicate P” This is embodied in a tool called the consultator. a general tool for data input - the capturer - wich allows inputting appropriate data for any file. a tool for report production - the report printer - which allows design of arbitrary output reports. a specification for transformations from several input files into one or more output files - the file transformer - and its corresponding tool (program to interpret such notation). The above tools allow for input, consultation or retrieval, transformations (“computation” or “processing” of data into results) among files, and report generation, all of these without wr i ting programs in high level languages (Pascal, Cobol,...). Instead, we use a simpler description of (a) the screen to be presented for inputting data; (b) the query or predicate; (c) the transformation; (d) the report. The description used in (a) through (d) can be considered as a concise language for specifying data-manipulation (v. gr, administrative or managerial) tasks. If the tools prove to be useful, one can expect considerable savings in the time and effort spent in specifying and programming such data-manipulation tasks. The system in being implemented in Pascal for an IBM-PC network.