Hypermedia Systems for Managing Descriptive Knowledge
Anyone who has accessed the World Wide Web has been exposed to hypermedia documents?a highly nonlinear and interactive mixture of text, graphics, images, video, and audio. [Note: the terms "hypermedia" and "hypertext" are used interchangeably throughout this document.] Abstractly, a hypermedia document consists of a network of chunks connected by links (see figure). A chunk (or page) is an organized collection of information on a single topic. Pages are internally self-contained and independently understandable. A link is an electronic cross-reference used to connect logically related pages. The act of linking pages creates the hypermedia document and at the same time creates one set of navigational jumps for readers to follow. Links simulate the mental association between pages in the mind of the author. The structure of a hypermedia document refers to those elements that deal only with the organization of pages. Structure commonly takes the form of tables of contents, outlines of pages, graphical diagrams of page interrelationships, indices, link organization, etc. The content of a hypermedia document refers to the domain-specific material that makes up the subject matter.
In contrast to natural language text documents, hypertext forces the author to explicitly highlight the structure (outline or concept map) first and foremost for the user. Only secondarily, is the user exposed to the content matter. It is the structure that guides the user, time and again, to try different paths in the hypermedia document. There are many possible sets of navigational jumps?other than the single one envisioned by the hypermedia author?for example, dynamic ones based on the users responses to questions or on the users navigational patterns. The author can no longer rely on sequential reading to present material. A reader can arrive at a particular location in the hypermedia document from many different starting points. Consequently, each page (or chunk) of the hypermedia document must be independently understandable, much as we demand that journal figures and tables be self-contained.
Hypermedia authoring methods sacrifice some generality to increase the power of text to communicate meaning more clearly and to increase its problem-solving power by reducing ambiguity (BROKEN-LINK BROKEN-LINK Table). Several examples of hypermedia knowledge management systems have been developed for the natural resource management area. Rauscher developed the Encyclopedia of AI Applications to Forest Science in 1991, the Ecology and Management of Aspen in 1995, the Northeast Decision Model Design Document in 1995, and Oak Regeneration: a Knowledge Synthesis in 1997 (link needed). Reynolds and Rauscher developed a Hypermedia Reference System to the Forest Ecosystem Management Assessment Team Report in 1995 .Robert Giles, professor emeritus at Virginia Polytechnic Institute and State University, has made available a Species-Specific Wildlife Management System (link needed).
The emergence of the Internet and widely available hypermedia authoring systems has led to a paradoxical situation. As early as 1945, Vannevar Bush, science advisor to President Truman, pointed out the need to develop information technology to synthesize and thereby compact the huge, unwieldy, fragmented nature of human knowledge. Bush?s prescience provided the motivation for scientific research into hypertext systems. Despite the current availability of a mature theory and practice of how to author powerful hypermedia systems, the typical HTML document is essentially a paper document in electronic form. A simple experiment will convince the reader of this reality. Use any capable internet search engine to query on the term ?ecosystem management?. We obtained an overwhelming 5,003 ?hits?. A large number of these sites are self-promotional in nature, i.e. advertisements for books or for projects that a particular university or government agency is working on. Some of the better sites simply provide paper documents in electronic form (i.e. linear, sequential text and illustrations that look, read, and convey information just like a paper document and which are, in fact, meant to be printed, rather than consumed in electronic form). For example, the Ecological Society of America provides a nice report on ?The Scientific Basis for Ecosystem Management? (link needed) that is 89 screen pages long. The Cato Policy Institute has available a very nicely written article warning of the dangers of ecosystem management that is 59 screen pages long. In contrast, good hypermedia authoring practice is that no single chunk or ?Internet Page? of content be longer than 3-5 screen pages and the shorter the better (2-3 screens). Comparing the above documents with those produced by Reynolds and Rauscher highlights a major improvement in knowledge synthesis, understandability, and ease of navigation. The truth is that most current hypermedia systems on the Internet do not help diminish knowledge fragmentation nor do they advance knowledge synthesis or knowledge management.
Encyclopedia ID: p1640
