Knowledge representation and reasoning

About: Knowledge representation and reasoning is a research topic. Over the lifetime, 20078 publications have been published within this topic receiving 446310 citations. The topic is also known as: KR & KR².

VT: An Expert Elevator Designer That Uses Knowledge-Based Backtracking

Abstract: VT (vertical transportation) is an expert system for handling the design of elevator systems that is currently in use at Westinghouse Elevator Company Although VT tries to postpone each decision in creating a design until all information that constrains the decision is known, for many decisions this postponement is not possible In these cases, VT uses the strategy of constructing a plausible approximation and successively refining it VT uses domain-specific knowledge to guide its backtracking search for successful refinements The VT architecture provides the basis for a knowledge representation that is used by SALT, an automated knowledge-acquisition tool SALT was used to build VT and provides an analysis of VT's knowledge base to assess its potential for convergence on a solution

Computing least common subsumers in description logics

Abstract: Description logics are a popular formalism for knowledge representation and reasoning. This paper introduces a new operation for description logics: computing the "least common subsumer" of a pair of descriptions. This operation computes the largest set of commonalities between two descriptions. After arguing for the usefulness of this operation, we analyze it by relating computation of the least common subsumer to the well-understood problem of testing subsumption; a close connection is shown in the restricted case of "structural subsumption". We also present a method for computing the least common subsumer of "attribute chain equalities" , and analyze the tractability of computing the least common subsumer of a set of descriptions--an important operation in inductive learning.

Datalog+/-: A Family of Logical Knowledge Representation and Query Languages for New Applications

Abstract: This paper summarizes results on a recently introduced family of Datalog-based languages, called Datalog+/-, which is a new framework for tractable ontology querying, and for a variety of other applications. Datalog+/- extends plain Datalog by features such as existentially quantified rule heads and, at the same time, restricts the rule syntax so as to achieve decidability and tractability. In particular, we discuss three paradigms ensuring decidability: chase termination, guardedness, and stickiness.

An object-oriented representation for product and design processes

Abstract: We report on the development of a knowledge representation model, which is based on the SHARED object model reported in Shared Workspaces for Computer-Aided Collaborative Engineering (Wong, A. and Sriram, D., Technical Report, IESL 93-06, Intelligent Engineering Systems Laboratory, Department of Civil Engineering, MIT, March, 1993) and Research in Engineering Design (Wong, A. and Sriram, D., SHARED: An Information Model for Cooperative Product Development, 1993, Fall, 21-39). Our current model is implemented as a layered scheme, that incorporates both an evolving artifact and its associated design process. To represent artifacts as they evolve, we define objects recursively without a pre-defined granularity on this recursive decomposition. This eliminates the need for translations between levels of abstraction in the design process. The SHARED model extends traditional OOP in three ways: 1. by allowing explicit relationship classes with inheritance hierarchies; 2. by permitting constraints to be associated with objects and relationships; and 3. by comparing `similar' objects at three different levels (form, function and behavior). Five primitive objects define the design process: goal, plan, specification, decision and context. Goal objects achieve function, introduce constraints, introduce new artifacts or modify existing ones, and create subgoals. Plan objects order goals and link a product hierarchy to a process hierarchy. Specification objects define user inputs as constraints. Decision objects relate goals to user decisions and context objects describe the design context. Operators that are applied to design objects collectively form a representation of the design process for a given context. The representation is robust enough to effectively model four design paradigms [described in Journal of CAD (Gorti, S. and Sriram, R. D., Symbol to Form Mapping: a Framework for Conceptual Design, 1996, 28 (11), 853–870)]: top-down decomposition, step-wise refinement, bottom-up composition and constraint propagation. To demonstrate this, we represent the designs of two TV remote controllers in the SHARED architecture. The example reveals that certain aspects of artifact knowledge are essentially context-independent and that this representation can be a foundation for robust knowledge-based systems in design.