Semantic Net Based Hypertext for Authoring and Reuse

Author:

Weigang Wang

Email:

weigang.wang-at-manchester.ac.uk

Advisor:

Roy Rada

Award Date:

July 1995

Institution:

The University of Liverpool

Institution Location:

Liverpool, UK

Web Location:

http://www.informatics.manchester.ac.uk/~mcassww/WeigangWangPhD.pdf

Abstract:

The study of hypertext covers a multidisciplinary scientific and technological domain, and addresses the theories, principles, techniques and tools to structure, manage and use information in electronic format. The modularity of information units and the flexibility in organising these units make hypertext also appropriate for document reuse. A conceptual framework developed for software reuse is applied to document reuse. The framework describes reuse in terms of the processes involved. The focus of the research is hypertext methodologies and tools that support the document reuse processes, which include document creation, document management, document retrieval, and document reorganisation.

Three prototype hypertext systems have been designed and implemented progressively. In each prototype, models were modified and new engineering components were added. In this way a novel system was systematically built. For the first prototype, an unstructured semantic net is exploited and an authoring tool is provided. The prototype uses a knowledge-based traversal algorithm to facilitate document reorganisation. The structural and semantic consistency of the semantic net is fully left in the users’ hands. The results indicate that the traversal method has not provided a practical solution for document reorganisation. The useful output from the traversal method depends on meaningful link and node typing. Such typing is hard to achieve with an unstructured semantic net.

Then, a semi-structured semantic net was exploited and a collaborative hypertext system was built. A hierarchical view generating method was developed. Although the system suggests a small set of link types for different structures, the structural and semantic consistency of the semantic net is again left in the users’ hands. The system has proven to be useful for authoring and reusing conventional documents in a tree structure. Authors, however, were not practically able to produce hypertext that had links other than those in conventional documents in a tree structure.

Finally, a structured semantic net has been exploited. The requirements for hypertext-based document reuse have been elicited and a domain model for structured hypertext has been developed. The domain model and requirements have been formalised into a rigorous semantic data model, which integrates logical structure and domain semantics into hypertext. A new collaborative hypertext system has been developed with the model. It can define and enforce a set of rules to maintain the structural and semantic consistency of the semantic net. Concrete methods have been developed to support the life-cycle of document reuse. In the life-cycle, reorganising, the final step in reuse, is considered as a process of copying with changes. Multi-hierarchies can be created by using various copying operators that allow a mixture of sharing and non-sharing of changes on contents and structures. Many examples and case studies have highlighted the value of this approach.

A structured semantic net can be a unifying representation for some of the important organisational features of small- and large-volume hypertext. The capability of representing knowledge about a specific domain with the structured semantic net can improve hypertext organisation and reusability. Collaborative hypertext can play an important role in creating an environment where reuse is an integral part of the authoring process. The methodology and system produced in this work have extended 1) traditional indexing from the document level to the document component level, 2) traditional text outlining to hypertext outlining, and 3) simple content cutting-and-pasting to content and structure sharing, referring, copying and modifying across a well organised information space. Although the research focuses on technical document reuse, the methodology and tools demonstrate the potential for application in business, scientific, and personal information management.