Tools for Assembling and Managing Scalable Knowledge Bases (OntoLoom).

Project Summary

University of Southern California,
Information Sciences Institute


Robert MacGregor
[email protected]
(310) 448-8719

Tools for Assembling and Managing Scalable Knowledge Bases (OntoLoom).

ISI is developing a new system, called Knowledge Builder, to construct, manage, and reason with very large, high-performance knowledge bases. Knowledge Builder will be a Web-based collaboration system (derived from ISI's Ontosaurus Tool) for assembling, validating, maintaining, and exporting large ontologies and knowledge bases. Underlying Knowledge Builder is a scalable KR system (called PowerLoom®) able to represent and reason effectively with a library of knowledge bases too large to fit within the virtual memory of a single workstation.

Knowledge Builder focusses the development of ISI's Ontosaurus and PowerLoom systems toward the task of managing large ontologies. It will expand existing Ontosaurus capabilities with a full-suite of operations for knowledge base assemby and manipulation. We will will extend PowerLoom with view, abstraction, and mapping components needed to support KB construction, and we will make it scalable by developing a "paging module" that couples it to commercial storage systems.

To insure the successful use of Knowledge Builder both within the research community and in fielded DARPA applications, we place unusual stress on interoperability and portability. Knowledge Builder will be able to communicate using a variety of KR languages (KIF, Ontolingua, Loom®, PowerLoom and GFP), and it will support direct, efficient interfaces to multiple native object systems (C++, Java, IDL, and CLOS). ISI's unique STELLA translator technology will enable us to release C++, Common Lisp, and Java versions of Knowledge Builder.

Our work during this period has focused primarily on readying our PowerLoom knowledge representation system for its first release, scheduled for September, 1997. PowerLoom will provide the foundation for the scalable reasong system used by Knowledge Builder. We have also developed a new paradigm for coupling classifier-based systems like Loom and PowerLoom to conventional software. Our "knowledge amplifier" inputs data stored in an object system, applies knowledge-based inferencing to it, and then exports the enhanced result back to the object system. This technology will help programs like JFACC to overcome the representational limitations they face using current object-based software tools.


Released C++ and Common-Lisp versions of the PowerLoom knowledge representation system. The C++-based PowerLoom will facilitate the transition of AI technology to non-Lisp programming environments.

Enhanced Ontosaurus with a "highlight" feature that makes it easy to differentiate knowledge acquired from different sources. Demonstrated the highlighting on a knowledge base containing a Cyc ontology merged with a JFACC ontology.

Demonstrated a prototype "knowledge amplifier" that caches the results of knowledge-based inferencing as augmentations to an object base or database. The amplifier introduces a new paradigm for supporting interactions between conventional software and AI software.

Develop a "knowledge paging module" that interfaces PowerLoom to a commercial data storage system. This will create a platform for conducting experiments on how to efficiently perform complex reasoning over very large knowledge bases.

Develop a schema mapping tool that will facilitate the exchange of knowledge between a knowledge base and other database(s) or knowledge base(s). Use the tool to semi-automate the process of coupling an object-oriented application to a knowledge representation system using our "knowledge amplifier" approach.

Upgrade Ontosaurus' capabilities for assisting the process of aquiring, merging, and maintaining large ontologies. Use the enhanced tool to support knowledge acquisition (KA) acitivities within the HPKB and JFACC programs.

Extend PowerLoom's translator repertoire with a bi-directional Ontolingua translator and a GFP interface, thereby enabling its use as a knowledge server within DARPA research and ISO-services programs.

PowerLoom's precedessor, ISI's Loom system, has been distributed to more than 100 universities and corporations, and it is being used by numerous ARPA contractors in ARPA's Intelligent Integration of Information (I*3), planning (ARPI), Air Campaign Planning (ACP), machine translation, and image understanding programs. We have similar goals for PowerLoom and Ontosaurus. ISI has made an unusually strong commitment to developing AI technology that will transition easily. We now develop all of our software in the STELLA language; a STELLA program is automatically translable into both C++ and Common Lisp (a STELLA-to-Java translator is planned as a future HPKB milestone). Our Fall '97 release of PowerLoom will represent the first occurrence of a knowledge representation system written in C++.



Loom and PowerLoom Knowledge Representation Languages

Loom and PowerLoom are knowledge representation languages that provide an ability to define and reason with terms expressed in a logic-based description language. The reasoning includes a classifier for automatically maintaining a hierarchy of terms based on their definitions; a constraint checker that determines when concepts or instances have inconsistent (incoherent) definitions or attributes; and a powerful query language.

Ontosaurus Web Browser

Ontosaurus is a graphical Web-based browser for Loom and PowerLoom knowledge bases. Ontosaurus allows viewing and interacting with a live Loom knowledge base using a standard HTTP protocol. Different views and a query-by-example system are supported by the software.
Loom and PowerLoom are registered trademarks of the University of Southern California.

Sciences Institute ISI Intelligent
Systems Division Loom Home Page PowerLoom Home Page