Position Paper for Workshop on Rule Languages for Interoperability
by Aubrey Jackson, Waymaker, Inc.
and David Scott, Haplos, Inc.

1 Introduction

We believe that a successful general framework for web interoperability will not be based on a language for sharing rules but a rule language for defining data collectives and the topologies into which they can be arranged. The rule language will need to describe a collective's membership policies, internal security policies, data standards, functional concerns, members, and rules for exposure to other collectives. Depending on the rules for participation in the collective, members might not be required to implement rule languages or sophisticated data models themselves. By plugging into a collective, a member will inherit the formal representation and translation resources of the collective.

We believe that solutions which depend upon the widespread adoption of semantic web technologies or the automated generation and translation of ontologies will have a narrow range of application. Our proposed solution encourages the pooling of resources to reduce the cost of integration. Our own recent work concerns data sharing between loosely related verticals in the commercial real estate industry -- eg., between realtors, appraisers, building managers, investment trusts, title companies, insurers, banks, contruction contractors, and others. These verticals already have their own data standards which they have taken years to develop (although the adoption of these standards is very uneven.) The goal is to encourage the further development and adoption of the existing standards and to come up with a framework for the exchange of data between the different verticals. [Note: So far, the use of metadata in this space (as defined by the Real Estate Transaction Standard) has been a failure.]

2 Background

In the Call for Participation, it was noted that current work on rule languages and ontology by computer scientists has its roots in prior work in formal logic. The optimistic forecasts regarding the outcome of this current research echoes the optimistic predictions of the logicians, linguists, and philosophers of the 1920s, '30s, and '40s regarding their own early work. Carnap's
Aufbau (The Logical Structure of the World) seemed to be the beginning of a program in which human knowledge would be formally explicated in a universal, unambiguous language. Here and there, critics pointed to areas which, they claimed, would resist formal analysis. However, the logical positivists believed that most of these areas would yield to analysis, in whole or part, in the incremental progress of their project. During the 1950s, '60s, and '70s, the logical positivists began to question their own project -- but not so much because of the discovery of areas that resisted formalization.

As their studies matured, the logical positivists encountered difficulties regarding the resolution of formal ontologies. This touched off an internal critique concerning the limits of the formal program. Quine, one of the leading lights of the analytic school, helped kill the program with his related theses of Ontological Relativity, the Indeterminacy of Translation, and the Underdetermination of Theories (translation being, itself, a kind of theory.) Formal analysis, using the tools and techniques of the logical positivists, continues, but not in the service of a grand unifying program to formalize all of human knowledge.

Similarly, recent blog chatter reveals skepticism regarding the promise of the Semantic Web. The discussion generated by Clay Shirky's pessimistic prognosis for its success helped call attention to some of the hyperbole surrounding the Semantic Web and generated some frank evaluations of what its development will yield by people currently working with this technology. A view repeated by many participants in the discussion was that what has and will emerge is not a global ontology or a universal framework for resolving ontologies, but a
patchwork of local ontologies. Rule languages and core data types will lessen the burden of integrating these ontologies; but in many instances, the task of integrating local ontologies will be done by committee, not by computer.

The primary focus of these technologists is in using rule languages and sophisticated ontologies to increase the expressive power of their data models. They expect that this greater expressive power will lessen but not solve the problem of data integration. It is our belief that a successful framework for interoperation on the web will take for granted the patchwork of local ontologies which cannot be resolved through formal means alone. Furthermore, if it is to be widely adopted, it must facilitate the integration of resources which do not themselves support rule languages or formal ontologies. (The high cost of implementation and the shortage of qualified ontologists will slow the adoption of sophisticated data modeling.)

3 Proposal

The solution we are investigating is a framework for linking together disparate database sources into a collaborative network. The network is subdivided into groups which are defined by their membership policies, services, supported data standards, and connections to other groups in the network. In general, a participant selects a group which supports the standard to which the participant can most easily map its existing resources. However, a participant can join as many groups as necessary, offering differing views of its resources to each group. Each group is governed by a local ontology and rule set which may remain internally implicit. That ontology is made explicit only to the exent necesssary to expose a group's resources to other groups. Translation services are provided by the group; so, depending on the network's topology, the participant potentially only needs to map his resources once (ie., to his selected group) in order to expose them to the network as a whole. Our intent is to encourage the flourishing of communities around local ontologies, but to allow them to interact with other communities through black-box translation services that are a well-identified, integral part of the community's network.