Page Indexing for Textual Information Retrieval Systems

150 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983.A number of applications exist for systems which can store and interactively retrieve from very large natural language textual databases. This thesis discusses conventional approaches to the design of such systems. The notion of page indexing is introduced as a new scheme for doing information retrieval from natural language full-text databases.The structure of a page indexed database is described and the algorithms needed to do retrieval using the page index are presented. Some characteristics of page indexed text are analyzed and measured in order to estimate the size of the page index, and to show how the size of the index is related to the page size. One of the advantages of the page indexing scheme is the ease with which such a system can be analyzed. This analysis is based on characteristics of the hardware used to implement the system and on characteristics of queries. Finally, three hypothetical systems are proposed and analyzed using the techniques and methodologies developed in this thesis. These systems range from a microprocessor for a database of 250 megabytes to a large computer system employing multiple special purpose processors for a database of 50 gigabytes.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Abstract Event Synchronization Analysis for Debuggi:ng Parallel Programs *

One of the major difficulties of explicit parallel pro-gramming for a shared memory machine model is de-tecting the potential for nondeterminacy and identi-fying its causes. There will often be shared variables in a parallel program, and the tasks comprising the program may need to be synchronized when accessing these variables. This paper discusses this problem and presents a method for automatically detecting non-determinacy in parallel programs that utilize event style synchro-nization instructions, using the Post, Wait, and Clear primitives. With event style synchronization, espe-cially when there are many references to the same event, the difficulty lies in computing the execution order that is guaranteed given the synchronization in-structions and the sequential components of the pro-gram. The main result in this paper is an algorithm that computes such an execution order and yields a Task Graph upon which a nondeterminacy detection algorithm can be applied. We have focused on events because they are a frequently used synchronization mechanism in par-allel versions of Fortran, including Cray [Cray87]