The subject of this paper is the integration of multi-layered Artificial Neural Networks(ANN) with probability density functions such as Gaussian mixtures found in continuous density Hidden Markov Models (HMM). In the first part of this paper we present an ANN/HMM hybrid in which all the parameters of the the system are simultaneously optimized with respect to a single criterion. In the second part of this paper, we study the relationship between the density of the inputs of the network and the density of the outputs of the networks. A few experiments are presented to explore how to perform density estimation with ANNs. 1 INTRODUCTION This paper studies the integration of Artificial Neural Networks (ANN) with probability densityfunctions (pdf) such as the Gaussian mixtures often used in continuous density Hidden Markov Models. The ANNs considered here are multi-layered or recurrent networks with hyperbolic tangent hidden units.

We propose and empirically evaluate a method for the extraction of expertcomprehensible rules from trained neural networks.

The Digital Services Research Group and its predecessor groups and offshoots in Digital Equipment Corporation have been mobilizing leading-edge AI research to bear on real-life problems that face the corporation and its customers. The general strategy of the group is to explore emerging techniques relevant to service and support needs through developing rapid prototypes, deploying these prototypes, and incorporating feedback from users. With over 32 major projects undertaken during the past decade, we have worked on broad spectrum of problems and explored a variety of advanced AI techniques. This article describes the current AI activities in five areas: (1) enterprise advisory systems, (2) natural language processing and textual information retrieval, (3) largescale knowledge base management and access, (4) software configuration management, and (5) intrusion detection.

I met Allen for the first time when I came for a two semester long visit to Carnegie Mellon University in 1968. This encounter was a distinct factor in my later decision to join the faculty at Carnegie Mellon University.

AAAI Workshop on Cooperation Among Carifio, Mike see Rewari, Anil. Language, A, 13(1): Spring 1992, 9-Chalupsky, Hans see Shapiro, Stuart 13(2): Summer 1992, 39-42. Fourth International Symposium on Chen, Tony see Hadavi, Khosrow. Christopher J. Knowledge Discovery Adler, Mark see Rewari, Anil. Functional Categorization of Knowledge: Downes, Stephen see Dietrich, Eric.

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Allen Newell was one of the founders and truly great scientists of AI. His contributions included foundational concepts and ground-breaking systems. His career was defined by the pursuit of a single, fundamental issue: the nature of the human mind. This article traces his pursuit from his early work on search and list processing in systems such as the LOGIC THEORIST and the GENERAL PROBLEM SOLVER; through his work on problem spaces, human problem solving, and production systems; through his final work on unified theories of cognition and SOAR.

Another issue concerned The survey of 80 KBS developers in Knowledge-Based Systems, Marc Ayel structural validation of KBS, given financial domains by Daniel O'Leary and Jean-Pierre Laurent, eds., John that the architecture of these systems opens the collection and raises some Wiley and Sons, Chichester, England, (having separate knowledge base and interesting points. VVT is revealed to 1991, 219 pp., $49.95, ISBN 0-471- inference engine components) was be a significant concern, with developers 93018-0 (paper). Testing his volume contains a selection First European Workshop on studies were launched to determine with real and contrived test cases was Verification, Validation, and Test of the applicability of software engineering found to account for about half the Knowledge-Based Systems, held evaluation techniques to overall VVT effort on average, with during the 1990 European Conference KBSs and to develop new techniques direct inspection of the knowledge on Artificial Intelligence (ECAI specific to KBSs. Several such studies base accounting for another 30 percent 90) in Stockholm, Sweden. In reviewing were initiated by organizations that in the survey.

I met Allen for the first time when I came for a two semester long visit to Carnegie Mellon University in 1968. This encounter was a distinct factor in my later decision to join the faculty at Carnegie Mellon University.

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