Reference: V. K. Chaudhri, A. Farquhar, R. Fikes, P. D. Karp, & J. P. Rice. Open Knowledge Base Connectivity 2.0. Knowledge Systems, AI Laboratory, 1998.
Abstract: This document specifies a protocol for accessing knowledge bases (KBs) stored in knowledge representation systems (KRSs). By KRS we mean both systems that would traditionally be considered KRSs, as well as can be viewed as a KRS, for example, an object-oriented database. The protocol, called the Open Knowledge Base Connectivity (OKBC), provides a set of operations for a generic interface to underlying KRSs. The interface layer allows an application some independence from the idiosyncrasies of specific KRS software and enables the development of generic tools (e.g., graphical browsers and editors) that operate on many KRSs. OKBC implementations exist for several programming languages, including Java, C (client implementation only), and Common Lisp, and provide access to KBs both locally and over a network.
OKBC is complementary to language specifications developed to support knowledge sharing. KIF [4], the Knowledge Interchange Format, provides a declarative language for describing knowledge. As a pure specification language, KIF does not include commands for knowledge base query or manipulation. Furthermore, KIF is far more expressive than most KRSs. OKBC focuses on operations that are efficiently supported by most KRSs (e.g., operations on frames, slots, facets -- inheritance and slot constraint checking). OKBC is intended to be well impedance-matched to the sorts of operations typically performed by applications that view or manipulate object-oriented KRSs.
A postscript version of this document can be found here
Reference: R. Fikes, A. Farquhar, & J. Rice. Tools for Assembling Modular Ontologies in Ontolingua. Knowledge Systems, AI Laboratory, 1997.
Abstract: The Ontolingua ontology development environment provides a suite of ontology authoring tools and a library of modular, reusable ontologies. The environment is available as a World Wide Web service and has a substantial user community. The tools in Ontolingua are oriented toward the authoring of ontologies by assembling and extending ontologies obtained from thea library. In this paper, we describe Ontolingua's formalism for combining the axioms, definitions, and words (non-logical symbols) of multiple ontologies. We also describe Ontolingua's facilities that enable renaming of non-logical symbols from multiple component ontologies and that provide unambiguous mapping between words and text strings disambiguate symbol references during input and output. These features of Ontolingua support cyclic inclusion graphs and enable users to extend ontologies in multiple ways such as adding simplifying assumptions and extending the domains of polymorphic operators.
Full paper available here.
Reference: R. Fikes & A. Farquhar. Large-Scale Repositories of Highly Expressive Reusable Knowledge. Knowledge Systems, AI Laboratory, 1997.
Abstract: We present a vision of next generation tools and services that will enable the widespread development and use of computer interpretable ontologies. Central to that vision is the notion of distributed ontology repositories resident on multiple ontology servers containing large-scale highly structured ontologies and supported by sophisticated ontology construction, testing, merging, extraction, reformulation, and translation tools. The key enabler in the distributed ontology repository architecture is a network application programming interface (API) for ontology servers that will support storage, manipulation, and access to the contents of ontologies on a server. We describe how OKBC, an API specifically designed to provide knowledge-level interoperability among server and client systems, provides that support. We then consider the criteria for an ontology representation language and an agenda of extensions to current ontology representation languages that address major deficiencies in those languages and appear to be attainable in next generation languages. Finally, we address the issue of what reasoning is needed to support ontology repository construction and use, and describe a deductive retrieval facility under development for the Ontolingua ontology server that includes a theorem prover which runs as a background task to reformulate sentences so that are accessible by the server's special purpose high speed retrieval methods.
Notes: (Updated March 1998).
Full paper available here.
Reference: A. Farquhar, R. Fikes, & J. Rice. The Ontolingua Server: A Tool for Collaborative Ontology Construction. Knowledge Systems, AI Laboratory, 1996.
Abstract: Reusable ontologies are becoming increasingly important for tasks such as information integration, knowledge-level interoperation, and knowledge-base development. We have developed a set of tools and services to support the process of achieving consensus on common shared ontologies by geographically distributed groups. These tools make use of the world-wide web to enable wide access and provide users with the ability to pub-lish, browse, create, and edit ontologies stored on an ontology server. Users can quickly assemble a new ontology from a library of modules. We discuss how our system was constructed, how it exploits existing protocols and browsing tools, and our experience supporting hundreds of users. We describe applications using our tools to achieve con-sensus on ontologies and to integrate information. The Ontolingua Server may be accessed through the URL http://ontolingua.stanford.edu/.
Full paper available here.
Abstract: We show how to deliver a sophisticated, yet intuitive, interactive application over the web using off-the-shelf web browsers as the interaction medium. This attracts a large user community, improves the rate of user acceptance, and avoids many of the pitfalls of software distribution.
Web delivery imposes a novel set of constraints on user interface design. We outline the tradeoffs in this design space, motivate the choices necessary to deliver an application, and detail the lessons learned in the process.
These issues are crucial because the growing popularity of the web guarantees that software delivery over the web will become ever more wide-spread.
This application is publicly available at: http://www-ksl-svc.stanford.edu:5915/
Full paper available in PostScript form here.
A much extended version of this paper as a hypertext document with numerous worked examples, slide shows and design mockups is here.
Abstract: Information integration is enabled by having a precisely defined common terminology. We call this combination of terminology and definitions an ontology. We have developed a set of tools and services to support the process of achieving consensus on such a common shared ontologies by geographically distributed groups. These tools make use of the world-wide web to enable wide access and provide users with the ability to publish, browse, create, and edit ontologies stored on an ontology server. Users can quickly assemble a new ontology from a library of modules. We discuss how our system was constructed, how it exploits existing protocols and browsing tools, and our experience supporting hundreds of users. We describe applications using our tools to achieve consensus on ontologies and to integrate information. The ontology server may be accessed through the URL http://www-ksl-svc.stanford.edu:5915/
Full paper available in PostScript form here.
Abstract: For health care providers to share computing resources and medical application programs across different sites, those applications must share a common medical vocabulary. To construct a common vocabulary, researchers must have an architecture that supports collaborative, networked development. In this paper, we present a web-based server architecture for the collaborative development of a medical vocabulary: a system that provides network services in support of medical applications that need a common, controlled medical terminology. The server supports vocabulary browsing and editing and can respond to direct programmatic queries about vocabulary terms. We have tested the programmatic query-response capability of the vocabulary server with a medical application that determines when patients who have HIV infection may be eligible for certain clinical trials. Our emphasis in this paper is not on the content of the vocabulary, but rather on the communication protocol and the tools that enable collaborative improvement of the vocabulary by any network-connected user.
Notes: Original version 4/95 - updated 8/95.
Full paper available in PostScript form here.
Abstract: We describe a new project whose objective is to develop key technologies that will enable vendors and buyers to build and maintain network-based information brokers capable of retrieving information about services and products via the Internet from multiple vendor catalogs and data bases for both human and computer-based clients. The ability to obtain relevant information in a timely and cost efficient manner is central to the effective performance of most tasks in our society. The widespread availability of computer-based information brokers will provide that ability to large communities by significantly facilitating effective access to the broad range of information that is rapidly becoming available on the Internet. The general availability of the technology to build and maintain information brokers will enable an industry to be established whose primary products are computer-based network-accessible brokering services.
Full paper available in PostScript form here.
Abstract: It is essential to reduce the cost of integrating information sources and to provide a path that allows for incremental integration that can be responsive to users' demands. This paper presents an approach to integrating disparate heterogeneous information sources that uses context logic. Our use of context logic reduces the up-front cost of integration, provides an incremental integration path, and allows semantic conflicts within a single information sources or between information sources to be expressed and resolved.
Full paper available in PostScript form here.