Ph.D. Thesis available: Neural networks learning differential data

Ryusuke Masuoka masuoka at flab.fujitsu.co.jp
Sun Oct 15 18:48:27 EDT 2000


Dear Connectionists,

I am pleased to announce the availability of my Ph.D. thesis for
download in electronic format.

Comments are welcome.

Regrads, 

Ryusuke

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Thesis:
-------

Title:	 	"Neural Networks Learning Differential Data"

Advisor:		Michio Yamada

URL:		http://lettuce.ms.u-tokyo.ac.jp/~masuoka/thesis/thesis.html

Abstract:
--------
Learning systems that learn from previous experiences and/or provided
examples of appropriate behaviors, allow the people to specify {\em
what} the systems should do for each case, not {\em how} systems
should act for each step.  That eases system users' burdens to a great
extent.

It is essential in efficient and accurate learning for supervised
learning systems such as neural networks to be able to utilize
knowledge in the forms of such as logical expressions, probability
distributions, and constraint on differential data along with provided
desirable input and output pairs.

Neural networks, which can learn constraint on differential data, have
already been applied to pattern recognition and differential
equations.  Other applications such as robotics have been suggested as
applications of neural networks learning differential data.

In this dissertation, we investigate the extended framework introduce
constraints on differential data into neural networks' learning.  We
also investigate other items that form the foundations for the
applications of neural networks learning differential data.

First, new and very general architecture and an algorithm are
introduced for multilayer perceptrons to learn differential data The
algorithm is applicable to learning differential data of orders not
only first but also higher than first and completely localized to each
unit in the multilayer perceptrons like the back propagation
algorithm.

Then the architecture and the algorithm are implemented as computer
programs. This required high programming skills and great amount of
care.  The main module is programmed in C++.

The implementation is used to conduct experiments among others to show
convergence of neural networks with differential data of up to third
order.

Along with the architecture and the algorithm, we give analyses of
neural networks learning differential data such as comparison with
extra pattern scheme, how learnings work, sample complexity, effects
of irrelevant features, and noise robustness.

A new application of neural networks learning differential data to
continuous action generation in reinforcement learning and its
experiments using the implementation are described.  The problem is
reduced to realization of a random vector generator for a given
probability distribution, which corresponds to solving a differential
equation of first order.

In addition to the above application to reinforcement learning, two
other possible applications of neural networks learning differential
data are proposed. Those are differential equations and simulation of
human arm. For differential equations, we propose a very general
framework, which unifies differential equations, boundary conditions,
and other constraints.  For the simulation, we propose a natural
neural network implementation of the minimum-torque-change model.

Finally, we present results on higher order extensions to radial basis
function (RBF) networks of minimizing solutions with differential
error terms, best approximation property of the above solutions, and a
proof of $C^l$ denseness of RBF networks.

Through these detailed accounts of architecture, an algorithm, an
implementation, analyses, and applications, this dissertation as a
whole lays the foundations for applications of neural networks
learning differential data as learning systems and will help promote
their further applications.

------------------------------------------------------------

Ryusuke Masuoka, Ph.D.
Senior Researcher
Intelligent Systems Laboratory
Fujitsu Laboratories Ltd.
1-4-3 Nakase, Mihama-ku
Chiba, 261-8588, Japan
Email:	masuoka at flab.fujitsu.co.jp
Web:	http://lettuce.ms.u-tokyo.ac.jp/~masuoka/



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