Uncertainty Reasoning for the World Wide Web Incubator Group Charter

Scope

The World Wide Web community envisions effortless interaction between humans and computers, seamless interoperability and information exchange among web applications, and rapid and accurate identification and invocation of appropriate Web services. As work with semantics and services grows more ambitious, there is increasing appreciation of the need for principled approaches to representing and reasoning under uncertainty. In this Charter, the term "uncertainty" is intended to encompass a variety of forms of incomplete knowledge, including incompleteness, inconclusiveness, vagueness, ambiguity, and others.  The term "uncertainty reasoning" is meant to denote the full range of methods designed for representing and reasoning with knowledge when Boolean truth values are unknown, unknowable, or inapplicable. Commonly applied approaches to uncertainty reasoning include probability theory, Dempster-Shafer theory, fuzzy logic, and numerous other methodologies. 

To illustrate, consider a few web-relevant reasoning challenges that could be addressed by reasoning under uncertainty.

• Information extracted from large information networks such as the World Wide Web is typically incomplete. The ability to exploit  partial information is very useful for identifying sources of service or information. For example, that an online service deals with greeting cards may be evidence that it also sells stationery. It is clear that search effectiveness could be improved by appropriate use of technologies for handling uncertainty.
• Much information on the World Wide Web is likely to be uncertain. Examples include weather forecasts or gambling odds. Canonical methods for representing and integrating such information are necessary for communicating it in a seamless fashion.
• Web information is also often incorrect or only partially correct, raising issues related to trust or credibility. Uncertainty representation and reasoning helps to resolve tension amongst information sources having different confidence and trust levels.
• The Semantic Web vision implies that numerous distinct but conceptually overlapping ontologies will co-exist and interoperate. It is likely that in such scenarios ontology mapping will benefit from the ability to represent degrees of membership and/or likelihoods of membership in categories of a target ontology, given information about class membership in the source ontology.
• Dynamic composability of Web Services will require runtime identification of processing and data resources and resolution of policy objectives. Uncertainty reasoning techniques may be necessary to resolve situations in which existing information is not definitive.

Uncertainty is an intrinsic feature of many of the required tasks, and a full realization of the World Wide Web as a source of processable data and services demands formalisms capable of representing and reasoning under uncertainty.  Although it is possible to use semantic markup languages such as OWL to represent qualitative and quantitative information about uncertainty, there is no established foundation for doing so. Therefore, each developer must come up with his/her own set of constructs for representing uncertainty. This is a recipe for disaster in an environment so dependent on interoperability among systems and applications.

Apart from the interoperability nightmare caused by proprietary uncertainty representations, there are ancillary issues such as how to balance representational power vs. simplicity of uncertainty representations, which uncertainty representation technique(s) addresses uses such as the examples listed above, how to ensure the consistency of representational formalisms and ontologies, etc. None of these issues can be addressed in a principled way by current Web standards.