Scalable Knowledge Composition (SKC)

Grant Proposal
Weekly Meetings
SKC Members only
Internal BSCW-Server


Related Topics
Commercial Integration


Contact Person
Marianne Siroker
The Scalable Knowledge Composition (SKC) project developed a novel approach to resolve semantic heterogeneity in Information systems. The SKC approach uses an algebra for composing ontologies that represent the terminologies from distinct, typically autonomous domains. Intersection is the most crucial operation since it identifies the articulation* over two ontologies, namely the terms where linkage occurs among the domains.

The intersection, and all other binary SKC algebra operations use articulation rules. Now source ontologies can be largely maintained autonomously, while the articulation rules will be maintained by groups benefitting from sharing and interoperation among domains. The SKC project lays the foundation for interoperatin among ontologies using the resulting articulations.

Now the problem of managing large knowledge bases is reduced to one of composition. No global agreement is needed among maintainers of disjoint ontologies. We believe that this distributed approach to knowledge maintenance is the best, and perhaps the only approach to make semantic interoperation truly scalable, since it partitions the ontology maintenance problem into small, disjoint and specialized domains. We are convinced that methods to enforce consistency, even if supported by edicts from `higher authorities' to force distinct, autonomous groups to use language coherently won't work. (The French academy can continue to tell us otherwise).

The project is hence conceptually quite innovative. To test the feasibility of this approach of the approach we will build some solid demonstrations. There are many open research questions that we expect to have to address in this process.
* Guha and Lenat's term

Project Participants


We would like to thank Rudi Studer, Erich Neuhold, Danladi Verheijen, Neetha Ratakonda and David Maluf for their enthusiastic contributions to our project in the past.

Current Work

Please try out an automatically generated Dictionary Ontology. The web interface is still experimental but will soon allow navigation of subsuming, specializing and kinship relationships between dictionary terms. These relationships are derived from the structure of the dictionary itself, without editing or other intervention, by using a simple ranking function. The source data is an on-line Webster's dictionary from 1913 available from the Gutenberg Project. We'll appreciate any comments.

This research effort is funded by AFOSR, with cooperation of the DARPA High-Performance Knowledge Base (HPKB) program. We have received some complementary funding by the Hughes Research Institute, Malibu, CA. Earlier, exploratory work has been supported by the Commercenet Consortium.

The SKC project duration extends to August 2000.

Publications specific to SKC

A progress report (here as an HTML slide show) on SKC research was made at the HPKB 6 month progress meeting, held in San Diego, 3-5 December, 1997. It's also available in Powerpoint format.
Here's a later presentation ( alternative pointer).
in Powerpoint format and more large graphics in Powerpoint format.

[WiederholdJ:99] Gio Wiederhold and Jan Jannink: " Composing Diverse Ontologies"; Stanford University Tech Report, August 1998.

[Jannink:98] Jan Jannink: "Rethinking Information Reuse"; abstract for DARPA Student Workshop, August 1998.

[JanninkSVW:98] Jan Jannink, Pichai Srinivasan, Danladi Verheijen, and Gio Wiederhold: "Encapsulation and Composition of Ontologies"; Proc. AAAI Summer Conference, Madison WI, AAAI, July 1998.

Related Publications

Our Definition of Ontologies

An abstract term is like a valise with a false bottom, you may put in what ideas you please, and take them out again, without being observed.
Alexis de Toqueville
Democracy in America, 1835.

The SKC project defines an ontology to be a set of terms and their relationships.

Terms refer to real-world and to abstract objects. Abstract objects are concepts which in turn can refer to sets of other abstract objects and real-world objects. The collections of real-world objects provides a grounding for the definitions, and an opportunity for validation of the meaning of the terms being employed.
The mapping of terms to objects will differ in various autonomous domains.

Relationships have semantic, and derived from that, structural significance. We may want to follow Sowa in keeping the number of relationship types constrained.
Multiple semantic relationship types may share structural relationship types, as IS-A, Ownership, Part-of, Reference, ... .
Again, the mapping of SKC relationship types to relationships employed in various ontologies will differ in various autonomous domains.
Instances of ontology types that the SKC algebra will have to consider include:

  • object oriented class hierarchies,
  • database schemas, often augmented with E-R or structural models
  • semi-structured databases
  • type specifications of enumerated sets
  • definitional thesauri, as UMLS
what is Cyc, ontolingua?

SKC specifically does not restrict its applicability to a purely extensional (object) or intensional (schema) definition of ontology, since its purpose is to support useful processing of extensions using intensional knowledge for all parties. To that end it is important that the intensional specification s include predicates or methods that permit the collection of extensional access to real-world objects.

We do not require ontologies to be complete specifications of a domain, but rather that usage of an ontology provide results complete with respect to the ontology.

comments are welcome, single iterations do not provide precision