Release and Resource News

June 26, 2006: PowerLoom® snapshots built from our latest CVS sources are now available.

May 26, 2006: PowerLoom® version 3.2 is released. PowerLoom license is now open source.

May 7, 2004: Loom® license is now open source.

January 23, 2003: Ontology Resources have been added to our site.

March 28, 2002: Ontosaurus 1.9 has been released!

July 12, 1999: Loom® 4.0 is available.

Loom Project Home Page

Loom® and PowerLoom® are knowledge representation languages developed by researchers in the Artificial Intelligence research group at the University of Southern California's Information Sciences Institute. The Loom project's goal is the development and fielding of advanced tools for knowledge representation and reasoning in Artificial Intelligence.

Loom and PowerLoom software is licensed under open source licenses, but it remains the intellectual property of the University of Southern California and it is not in the public domain.

Knowledge Representation Systems

PowerLoom®          Loom®

Loom Mailing List

The Loom community communicates via the mailing list To be added or removed from that list, connect to the mailing list manager for loom-forum. The list is now being maintained using Mailman software. Note that there is a separate mailing list for Powerloom.

Overview: Loom Knowledge Representation System

Loom is a language and environment for constructing intelligent applications. The heart of Loom is a knowledge representation system that is used to provide deductive support for the declarative portion of the Loom language. Declarative knowledge in Loom consists of definitions, rules, facts, and default rules. A deductive engine called a classifier utilizes forward-chaining, semantic unification and object-oriented truth maintainance technologies in order to compile the declarative knowledge into a network designed to efficiently support on-line deductive query processing.

A Quicktime movie describes how the classifier aids the development and automatically maintains the organization of a knowledge base.

The Loom system implements a logic-based pattern matcher that drives a production rule facility and a pattern-directed method dispatching facility that supports the definition of object-oriented methods. The high degree of integration between Loom's declarative and procedural components permits programmers to utilize logic programming, production rule, and object-oriented programming paradigms in a single application. Loom can also be used as a deductive layer that overlays an ordinary CLOS network. In this mode, users can obtain many of the benefits of using Loom without impacting the function or performance of their CLOS-based applications. A Retrospective on Loom provides more details.

Loom has been distributed to more than 80 universities and corporations, and is being used in numerous DARPA-sponsored projects in planning, software engineering and intelligent integration of information.

Loom Projects

The High Performance Knowledge Base (HPKB) program develops theories, tools, and knowledge bases to support advanced reasoning about complex problems arising in battle management and crisis understanding. Loom is one tool being used to develop and view HPKB ontologies. This is part of the future direction of Loom development.

Loom is being used in the JFACC project. This is a DARPA project to develop a tool to assist the Joint Forces Air Component Commander create air campaign plans. One application developed with Loom for this project is the Strategy Development Assistant (SDA). A description of the project is contained in our Final Report for the project.

Ontosaurus, a Web-based browser for Loom and PowerLoom knowledge bases is under development. This provides a dynamnically generated, hyper-linked interface to Loom and PowerLoom theories.

Loom was applied to the domain of computer image understanding in the VEIL project, an experiment that links a Loom-based domain model with geometric objects produced by an image understanding program. The use of a Loom superstructure enables interaction with the image system at a higher-level of abstraction--discourse is at the level of domain concepts such as buildings, headquarters and events rather than pixels or cubes.

The EXPECT project uses Loom as the representation language for constructing knowledge acquisition tools. EXPECT is developing a knowledge acquisition framework that empowers users and domain experts to augment, modify and adapt knowledge based systems without needing to understand the details of the system's implementation.

SIMS provides intelligent access to heterogeneous, distributed information sources (databases, knowledge bases, flat files, programs, etc.), while insulating human users and application programs from the need to be aware of the location of the sources, their query languages, organization, size, etc. A fixed vocabulary describing objects in the domain, their attributes and relationships among them is created using Loom. SIMS then accepts queries in this high-level uniform language.

To implement PowerLoom we developed a new programming language called STELLA, which is a Strongly Typed, Lisp-like LAnguage that can be translated into Lisp and C++. STELLA tries to preserve those features of Lisp that facilitate symbolic programming and rapid prototyping, while still allowing translation into readable as well as efficient C++ code.


Credits: The Quicktime movie was created by Bill Swartout.

Loom and PowerLoom are registered trademarks of the University of Southern California.

Sciences Institute ISI Intelligent
Systems Division