Uncertainty Reasoning for the World Wide Web Incubator Group Charter

The mission of the Uncertainty Reasoning for the World Wide Web (URW3) Incubator Group, part of the Incubator Activity, is to better define the challenge of reasoning with and representing uncertain information available through the World Wide Web and related WWW technologies.

Join the Uncertainty Reasoning for the World Wide Web Incubator Group.

End date 4 March 2008
Confidentiality Proceedings are public
Initial Chairs Kathryn Laskey, George Mason University (klaskey@gmu.edu)
Ken Laskey, The MITRE Corporation (klaskey@mitre.org).
Initiating Members
Usual Meeting Schedule Teleconferences: Every two weeks
Face-to-face: Once Annually


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.

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.

Success Criteria

The objectives of the URW3-XG are twofold: 

  1. To identify and describe situations on the scale of the World Wide Web for which uncertainty reasoning would significantly increase the potential for extracting useful information; 
  2. To identify methodologies that can be applied to these situations and the fundamentals of a standardized representation that could serve as the basis for information exchange necessary for these methodologies to be effectively used.

For the first objective, the URW3-XG would compile a set of use case descriptions to expand on the examples noted above and would solicit and further develop other examples of the kinds of information management challenges that would benefit (and if available, have already benefited) most from mechanisms for reasoning under uncertainty.

For the second objective, the URW3-XG will investigate proposed and implemented methodologies that may be applied to address the use cases developed under the first objective and that show promise as candidate solutions for uncertainty reasoning on the scale of the World Wide Web. The combination of use cases and associated methodologies would be examined to determine the most commonly required information and also that information that while not common may be especially important in select situations.  Given this analysis and a reasonably conclusive outcome, the URW3-XG would recommend those aspects that are considered most important to be included in a standard representation of vagueness and uncertainty.  The investigation would not advocate the choice of any one uncertainty methodology over others, but would seek to identify the type of information that would need to be saved as part of a general resource description and transmitted to a reasoning engine for useful processing. The recommended set may not include all identified information or address every use case in the initial collection.  However, the entire use case collection would provide a basis for discussing whether the recommended set is sufficient to advocate further actions along the W3C Recommendation Track, either as a separate Recommendation or as part of other related work.

Out of Scope

The scope does not include recommending a single methodology but to investigate whether standard representations of uncertainty can be identified that will support requirements across a wide spectrum of reasoning approaches.


The deliverable of URW3-XG will consist of a report that describes the work done by the XG and identifies the elements of uncertainty that need to be represented to support reasoning under uncertainty for the World Wide Web. The report will include a set of use cases illustrating conditions under which uncertainty reasoning is important. It will also provide an overview of and discuss the applicability to the World Wide Web of numerous uncertainty reasoning techniques and the information that needs to be represented for effective uncertainty reasoning to be possible.  Finally, it will include a bibliography of work relevant to the challenge of developing standardized representations for uncertainty and exploiting them in Web-based services and applications.


While the URW3 XG will not have direct dependencies, there are a number of efforts with which it intends to maintain close communications.  Drafts of this charter have been circulated to people associated with the Rules Interchange Format Working Group and the Health Care and Life Sciences Interest Group.  In addition, the charter itself notes the Fuzzy RuleML Technical Group under Related Initiatives.  The XG will solicit and welcome input from these and other efforts of which we become aware during the duration of the XG.


It is envisioned that the XG will have begin with 90-minute telecons every two weeks at a time that provides an adequate compromise over the various time zones of the interested participants.  This can be modified as the work proceeds.  During the telecons, the participants will review work done by individuals and sub-groups, and new work items will be defined and assigned.  Additionally, it may be useful to have a face-to-face meeting at a venue for which a significant number of XG participants are likely to attend.  

Expected participation follows the W3C Process Document discussion of Good Standing.


This group primarily conducts its work on the public mailing list public-xg-urw3@w3.org (archive) . The group's Member-only list is member-xg-urw3@w3.org (archive)

Information about the group (deliverables, participants, face-to-face meetings, teleconferences, etc.) is available from the Uncertainty Reasoning for the World Wide Web Incubator Group home page.

Decision Policy

As explained in the Process Document (section 3.3), this group will seek to make decisions when there is consensus. When the Chair puts a question and observes dissent, after due consideration of different opinions, the Chair should record a decision (possibly after a formal vote) and any objections, and move on.

Patent Policy

This Incubator Group provides an opportunity to share perspectives on the topic addressed by this charter. W3C reminds Incubator Group participants of their obligation to comply with patent disclosure obligations as set out in Section 6 of the W3C Patent Policy. While the Incubator Group does not produce Recommendation-track documents, when Incubator Group participants review Recommendation-track specifications from Working Groups, the patent disclosure obligations do apply.

Incubator Groups have as a goal to produce work that can be implemented on a Royalty Free basis, as defined in the W3C Patent Policy.

For more information about disclosure obligations for this group, please see the W3C Patent Policy Implementation.

Additional Information

Links to Related Initiatives

First Workshop on Uncertainty Reasoning for the Semantic Web. Proceedings.

Second Workshop on Uncertainty Reasoning for the Semantic Web. Proceedings.

Fuzzy RuleML Technical Group
Technical group studying uncertainty extensions to RuleML. 

Reference List

The following are some links to publications related to representing and reasoning under uncertainty in the World Wide Web.  This list is illustrative of the techniques the XG will investigate, and is not intended to be an exhaustive list. As part of the URW3-XG work, the list will be expanded into a more comprehensive bibliography of relevant work.

About this Charter

This charter for the Uncertainty Reasoning for the World Wide Web Incubator Group has been created according to the Incubator Group Procedures documentation. In the event of a conflict between this document or the provisions of any charter and the W3C Process, the W3C Process shall take precedence.

Kathryn Laskey, Ken Laskey, Paulo Costa

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