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An interactive information system has been developed for the College of Engineering to promote faster and more accurate trial advisement interviews between professors and the students they advice. This system also provides departmental administrative personnel with information to guide course scheduling. The system has the capability of providing the following information concerning undergraduate students enrolled in the College of Engineering: 1. A student's academic progress toward graduation. 2. A projection for four quarters of enrollments in engineering core courses. 3. The current status of any course offered as a requirement for obtaining a Bachelor's Degree in one of the Engineering disciplines. 4. The current status of any program leading to a Bachelor's Degree in any of the Engineering disciplines. The system provides the user with the additional capabilities to: 1. Update the database containing information pertaining to students enrolled in the College of Engineering. 2. Update the database containing information concerning courses offered as a requirement for obtaining a Bachelor's Degree in one of the Engineering disciplines. 3. Update the database containing information concerning the degree programs offered by the College of Engineering. The system is user oriented and operation does not require any knowledge of computer programming. Complete documentation is available to facilitate trouble-free user operation and programming any desirable additional capabilities in the future.

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This dissertation deals with the application of object-oriented database techniques to the problem of storage and access of information retrieval (IR) data, especially data that can be organized as a graph, such as a thesaurus encoded in semantic networks, or hypertext collections. Even traditional IR models can use graph representations of documents and concepts. This dissertation reports the development of an object-oriented model called the LEND (Large External object-oriented Network Database) model. This model contains not only features found in a typical object-oriented model but also those that specifically are designed for graph-structured data. A query language is provided facilitating the specification of graph-oriented queries. A prototype LEND system has been implemented to test the model on realistic graph-structured data. It adopts an open system architecture and design, and is easily extensible, like the LEND model itself. The research result of suitable data structures and algorithms (a class of minimal perfect hashing functions) for the efficient implementation of the LEND model is also reported. These data structures and algorithms enable retrieval of a node or a set of nodes in an optimal fashion. Placement of a large graph on a disk is studied as well. The method developed permits efficient traversal of graphs. / Ph. D.

Hypertext is a method of online information management and/or presentation where textual documents are parsed (modularized) into many nodes and inter-connected using machine-supported links. These systems have become increasingly popular in numerous applications. Unfortunately, few empirical investigations have been conducted concerning the usability and utility of hypertext, and the effusive claims made by many hypertext enthusiasts are largely unsubstantiated. This study investigated several usability issues relating to hypertext within the context of an information retrieval application. Of particular interest were system linking structures consisting of linear, hierarchical, network, and combination hierarchical/network configurations. These commonly used hypertext linking structures were imposed on a text-intensive geography database (GEO). GEO contains 187 nodes discussing a variety of topics concerning the countries of North Africa. In addition to the linking structures, the task variables of number of required links (to reach the answer) and task type were studied. Task type refers to expert programmers’ judgements as to whether a task is best suited to a hierarchical or network linking structure. The approach was to create a set of information retrieval (IR) tasks with specific characteristics (as determined by number of required links and task type), and to study the performance of each linking structure in completing these tasks. The intention was to identify the task situations under which each linking structure excels. Results indicate that hierarchical linking structures perform quite well for most IR tasks and perform significantly better than network linking. The combination condition performs no worse than hierarchical, yet, with the exception of task completion times, provides no consistent advantages over the hierarchical structure. Hence, it is concluded that, for novice users of a system, the performance advantages resulting from the inclusion of network links (in isolation or in combination with hierarchical) are not commensurate with the associated costs of creating such links. Ultimately, results are aimed at a better understanding of hypertext systems, their performance, and more judicious applications of these systems. / Ph. D.