The Hyper-Object Substrate: Hypermedia Supporting Incremental Formalization

Frank M. Shipman III

Department of Computer Science Texas A&M University College Station, TX 77843-3112 E-mail:

A number of systems have been built that integrate the knowledge representations of hypermedia and knowledge-based systems. Experiences with such systems have shown users are often unwilling to use the semi-formal mechanisms of such systems leaving much structure implicit rather than use the formal mechanisms provided [Shipman & Marshall 1994]. The problem remains that it is hard (1) to encode knowledge in the formal languages required by knowledge-based systems and (2) to provide computational support using the semi-formal knowledge found in hypermedia systems.

As a result of this problem, we have investigated a process of incremental formalization -- where users enter information into the system in an informal or semi-formal representation and gradually formalize it over time. This process allows for formalization to be demand driven, thereby not requiring effort of users prior to their acquiring benefits, and to be actively supported by the system, thereby reducing the difficulty of formalization for users [Shipman & McCall 1994].

The domain-independent Hyper-Object Substrate (HOS) integrates hypermedia and knowledge-based system styles of representations in such a way as to enable the incremental addition of formalism to any piece of information in the system. The use of a single representation for all information, not one representation for hypertext and another for formally represented domain knowledge, keeps users from needing to move to another part of the system in order to formalize information.

HOS actively supports incremental formalization with a set of tools that suggest new formalizations for addition to the information space. These suggestions are based on patterns in the informally and semi-formally represented information and the existing formalized knowledge in the information space. Suggestions need not be completely accurate to aid the user; suggestions provide a starting point which can be edited, thus changing part of the process of formalization from creation to modification.

Figure 1: Combination of design specification and design discussion in XNetwork.

XNetwork, an environment supporting computer network design, is one of several applications to be developed with HOS. Figure 1 shows the integration of more formally defined network components with less formally represented discussion of the design. Over time, communication between network designers can be migrated from informal textual annotations to modifications to the underlying formal representation of the domain.

HOS was also used for two knowledge-based systems class projects. Experiences from the development of XNetwork and the class projects show that the flexibility for incrementally adding and formalizing information is useful for the rapid prototyping and modification of knowledge-based applications.

In general, the integration of hypermedia and knowledge-based representations to support incrmemental formalization seems particularly applicable where systems are to both provide knowledge-based support and support for communication among users. In these cases, systems can use the naturally occurring communication between users as a source of informally represented information.

Shipman, F.M., and Marshall, C.C. "Formality Considered Harmful: Issues, Experiences, Emerging Themes, and Directions." Technical Report ISTL-CSA-94-08-02, Xerox Palo Alto Research Center, Palo Alto, CA, 1994.

Shipman, F.M., and McCall, R.J. "Supporting Knowledge-Base Evolution with Incremental Formalization." Proceedings of CHI '94, Boston, Massachusetts, (April 24-28, 1994) pp. 285-291.