Loom is a

knowledge representation Knowledge representation (KR) aims to model information in a structured manner to formally represent it as knowledge in knowledge-based systems whereas knowledge representation and reasoning (KRR, KR&R, or KR²) also aims to understand, reason, and ...

language developed by researchers in the

artificial intelligence Artificial intelligence (AI) is the capability of computer, computational systems to perform tasks typically associated with human intelligence, such as learning, reasoning, problem-solving, perception, and decision-making. It is a field of re ...

research group at the

University of Southern California The University of Southern California (USC, SC, or Southern Cal) is a Private university, private research university in Los Angeles, California, United States. Founded in 1880 by Robert M. Widney, it is the oldest private research university in ...

Information Sciences Institute The USC Information Sciences Institute (ISI) is a component of the University of Southern California (USC) Viterbi School of Engineering, and specializes in research and development in information processing, computing, and communications techn ...

. The leader of the Loom project and primary architect for Loom was Robert MacGregor. The research was primarily sponsored by the

Defense Advanced Research Projects Agency The Defense Advanced Research Projects Agency (DARPA) is a research and development agency of the United States Department of Defense responsible for the development of emerging technologies for use by the military. Originally known as the Adva ...

(DARPA). Loom is a frame-based language in the tradition of

KL-ONE KL-ONE (pronounced "kay ell won") is a knowledge representation Knowledge representation (KR) aims to model information in a structured manner to formally represent it as knowledge in knowledge-based systems whereas knowledge representation and ...

. As with KL-ONE, Loom has a formal semantics that maps declarations in Loom to statements in

set theory Set theory is the branch of mathematical logic that studies Set (mathematics), sets, which can be informally described as collections of objects. Although objects of any kind can be collected into a set, set theory – as a branch of mathema ...

and

first-order logic First-order logic, also called predicate logic, predicate calculus, or quantificational logic, is a collection of formal systems used in mathematics, philosophy, linguistics, and computer science. First-order logic uses quantified variables over ...

. This formal semantics enables a type of theorem prover engine called a classifier. The classifier can analyze Loom models (known as

ontologies In information science, an ontology encompasses a representation, formal naming, and definitions of the categories, properties, and relations between the concepts, data, or entities that pertain to one, many, or all domains of discourse. More ...

) and deduce various things about the model. For example, the classifier can discover new classes or change the subclass/superclass relations in the model. The classifier can also detect inconsistencies in the model declaration. This is a very powerful and fairly unusual capability in that it is capable of doing analysis at the ontology level, the level of declarations rather than at the implementation level as most inference engines do. The Loom project's goal is the development and fielding of advanced tools for

knowledge representation and reasoning Knowledge representation (KR) aims to model information in a structured manner to formally represent it as knowledge in knowledge-based systems whereas knowledge representation and reasoning (KRR, KR&R, or KR²) also aims to understand, reason, and ...

in artificial intelligence. Specifically to enable code to be generated from provably valid domain models. Loom is a language and environment for constructing intelligent applications. At its heart is a

system that combines a Frame-based language with an automatic classifier engine.

Declarative knowledge Declarative knowledge is an awareness of facts that can be expressed using declarative sentences. It is also called theoretical knowledge, descriptive knowledge, propositional knowledge, and knowledge-that. It is not restricted to one specific ...

in Loom consists of definitions, rules, facts, and default rules. A deductive engine called a classifier utilizes

forward chaining Forward chaining (or forward reasoning) is one of the two main methods of reasoning when using an inference engine and can be described logically as repeated application of ''modus ponens''. Forward chaining is a popular implementation strategy f ...

, semantic unification, and object-oriented truth maintenance technologies in order to compile the declarative knowledge into a network designed to efficiently support on-line deductive query processing. 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 Object-oriented programming (OOP) is a programming paradigm based on the concept of '' objects''. Objects can contain data (called fields, attributes or properties) and have actions they can perform (called procedures or methods and impleme ...

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 Clos may refer to: People * Clos (surname) Other uses * CLOS, Command line-of-sight, a method of guiding a missile to its intended target * Clos network, a kind of multistage switching network * Clos (vineyard), a walled vineyard; used in Fra ...

(Common Lisp Object System) 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. Loom has recently been succeeded by PowerLoom.

References

External links

Loom
Knowledge representation languages Declarative programming languages Common Lisp (programming language) software Ontology (information science) Computer-related introductions in 1999 {{compu-lang-stub