Introduction to Neural Network

By Hathaithep Wongsuvan

  What is a neural network (NN)?

   First of all, when we are talking about a neural network, we *should* usually
   better say "artificial neural network" (ANN), because that is what we mean
   most of the time. Biological neural networks are much more complicated in
   their elementary structures than the mathematical models we use for ANNs.

   A vague description is as follows:

   An ANN is a network of many very simple processors ("units"), each possibly
   having a (small amount of) local memory. The units are connected by
   unidirectional communication channels ("connections"), which carry numeric
   (as opposed to symbolic) data. The units operate only on their local data and on
   the inputs they receive via the connections.

   The design motivation is what distinguishes neural networks from other
   mathematical techniques:

   A neural network is a processing device, either an algorithm, or actual
   hardware, whose design was motivated by the design and functioning of
   human brains and components thereof.

   Most neural networks have some sort of "training" rule whereby the weights
   of connections are adjusted on the basis of presented patterns. In other words,
   neural networks "learn" from examples, just like children learn to recognize
   dogs from examples of dogs, and exhibit some structural capability for
   generalization.

   Neural networks normally have great potential for parallelism, since the
   computations of the components are independent of each other. 
  What can you do with a Neural Network and what not?
 
   In principle, NNs can compute any computable function, i.e. they can do
   everything a normal digital computer can do. Especially anything that can be
   represented as a mapping between vector spaces can be approximated to
   arbitrary precision by feedforward NNs (which is the most often used type).

   In practice, NNs are especially useful for mapping problems which are
   tolerant of some errors, have lots of example data available, but to which hard
   and fast rules can not easily be applied. NNs are, at least today, difficult to
   apply successfully to problems that concern manipulation of symbols and
   memory. 

   
  Who is concerned with Neural Networks?

   Neural Networks are interesting for quite a lot of very dissimilar people: 
    o Computer scientists want to find out about the properties of
      non-symbolic information processing with neural nets and about
      learning systems in general. 
    o Engineers of many kinds want to exploit the capabilities of neural
      networks on many areas (e.g. signal processing) to solve their
      application problems. 
    o Cognitive scientists view neural networks as a possible apparatus to
      describe models of thinking and conscience (High-level brain
      function). 
    o Neuro-physiologists use neural networks to describe and explore
      medium-level brain function (e.g. memory, sensory system, motorics). 
    o Physicists use neural networks to model phenomena in statistical
      mechanics and for a lot of other tasks. 
    o Biologists use Neural Networks to interpret nucleotide sequences. 
    o Philosophers and some other people may also be interested in Neural
      Networks for various reasons. 
  How many learning methods for NNs exist? Which?
 
   There are many many learning methods for NNs by now. Nobody knows
   exactly how many. New ones (at least variations of existing ones) are invented
   every week. Below is a collection of some of the most well known methods;
   not claiming to be complete.

   The main categorization of these methods is the distinction of supervised from
   unsupervised learning:

   In supervised learning, there is a "teacher" who in the learning phase "tells"
   the net how well it performs ("reinforcement learning") or what the correct
   behavior would have been ("fully supervised learning").

   In unsupervised learning the net is autonomous: it just looks at the data it is
   presented with, finds out about some of the properties of the data set and
   learns to reflect these properties in its output. What exactly these properties
   are, that the network can learn to recognise, depends on the particular network
   model and learning method.

   Many of these learning methods are closely connected with a certain (class of)
   network topology.

   Now here is the list, just giving some names:

   1. UNSUPERVISED LEARNING (i.e. without a "teacher"):
        1). Feedback Nets:
           a). Additive Grossberg (AG)
           b). Shunting Grossberg (SG)
           c). Binary Adaptive Resonance Theory (ART1)
           d). Analog Adaptive Resonance Theory (ART2, ART2a)
           e). Discrete Hopfield (DH)
           f). Continuous Hopfield (CH)
           g). Discrete Bi-directional Associative Memory (BAM)
           h). Temporal Associative Memory (TAM)
           i). Adaptive Bi-directional Associative Memory (ABAM)
           j). Kohonen Self-organizing Map/Topology-preserving map (SOM/TPM)
           k). Competitive learning
        2). Feedforward-only Nets:
           a). Learning Matrix (LM)
           b). Driver-Reinforcement Learning (DR)
           c). Linear Associative Memory (LAM)
           d). Optimal Linear Associative Memory (OLAM)
           e). Sparse Distributed Associative Memory (SDM)
           f). Fuzzy Associative Memory (FAM)
           g). Counterprogation (CPN)

   2. SUPERVISED LEARNING (i.e. with a "teacher"):
        1). Feedback Nets:
           a). Brain-State-in-a-Box (BSB)
           b). Fuzzy Cognitive Map (FCM)
           c). Boltzmann Machine (BM)
           d). Mean Field Annealing (MFT)
           e). Recurrent Cascade Correlation (RCC)
           f). Learning Vector Quantization (LVQ)
           g). Backpropagation through time (BPTT)
           h). Real-time recurrent learning (RTRL)
           i). Recurrent Extended Kalman Filter (EKF)
        2). Feedforward-only Nets:
           a). Perceptron
           b). Adaline, Madaline
           c). Backpropagation (BP)
           d). Cauchy Machine (CM)
           e). Adaptive Heuristic Critic (AHC)
           f). Time Delay Neural Network (TDNN)
           g). Associative Reward Penalty (ARP)
           h). Avalanche Matched Filter (AMF)
           i). Backpercolation (Perc)
           j). Artmap
           k). Adaptive Logic Network (ALN)
           l). Cascade Correlation (CasCor)
           m). Extended Kalman Filter(EKF)

  Good introductory literature about Neural Networks?

   1.) The best (subjectively, of course -- please don't flame me):
   
   Haykin, S. (1994). Neural Networks, a Comprehensive Foundation.
   Macmillan, New York, NY. "A very readable, well written intermediate to
   advanced text on NNs Perspective is primarily one of pattern recognition,
   estimation and signal processing. However, there are well-written chapters on
   neurodynamics and VLSI implementation. Though there is emphasis on
   formal mathematical models of NNs as universal approximators, statistical
   estimators, etc., there are also examples of NNs used in practical applications.
   The problem sets at the end of each chapter nicely complement the material. In
   the bibliography are over 1000 references. If one buys only one book on neural
   networks, this should be it."

   Hertz, J., Krogh, A., and Palmer, R. (1991). Introduction to the Theory of
   Neural Computation. Addison-Wesley: Redwood City, California. ISBN
   0-201-50395-6 (hardbound) and 0-201-51560-1 (paperbound) Comments:
   "My first impression is that this one is by far the best book on the topic. And
   it's below $30 for the paperback."; "Well written, theoretical (but not
   overwhelming)"; It provides a good balance of model development,
   computational algorithms, and applications. The mathematical derivations are
   especially well done"; "Nice mathematical analysis on the mechanism of
   different learning algorithms"; "It is NOT for mathematical beginner. If you
   don't have a good grasp of higher level math, this book can be really tough to
   get through."

   Masters,Timothy (1994). Practical Neural Network Recipes in C++. Academic
   Press, ISBN 0-12-479040-2, US $45 incl. disks. "Lots of very good practical
   advice which most other books lack."

   2.) Books for the beginner:

   Aleksander, I. and Morton, H. (1990). An Introduction to Neural Computing.
   Chapman and Hall. (ISBN 0-412-37780-2). Comments: "This book seems to
   be intended for the first year of university education."

   Beale, R. and Jackson, T. (1990). Neural Computing, an Introduction. Adam
   Hilger, IOP Publishing Ltd. : Bristol. (ISBN 0-85274-262-2). Comments:
   "It's clearly written. Lots of hints as to how to get the adaptive models covered
   to work (not always well explained in the original sources). Consistent
   mathematical terminology. Covers perceptrons, error-backpropagation,
   Kohonen self-org model, Hopfield type models, ART, and associative
   memories."

   Dayhoff, J. E. (1990). Neural Network Architectures: An Introduction. Van
   Nostrand Reinhold: New York. Comments: "Like Wasserman's book,
   Dayhoff's book is also very easy to understand".

   Fausett, L. V. (1994). Fundamentals of Neural Networks: Architectures,
   Algorithms and Applications, Prentice Hall, ISBN 0-13-334186-0. Also
   published as a Prentice Hall International Edition, ISBN 0-13-042250-9.
   Sample software (source code listings in C and Fortran) is included in an
   Instructor's Manual. "Intermediate in level between Wasserman and
   Hertz/Krogh/Palmer. Algorithms for a broad range of neural networks,
   including a chapter on Adaptive Resonance Theory with ART2. Simple
   examples for each network."

   Freeman, James (1994). Simulating Neural Networks with Mathematica,
   Addison-Wesley, ISBN: 0-201-56629-X. Helps the reader make his own
   NNs. The mathematica code for the programs in the book is also available
   through the internet: Send mail to MathSource@wri.com or try 
   http://www.wri.com/ on the World Wide Web.

   Hecht-Nielsen, R. (1990). Neurocomputing. Addison Wesley. Comments: "A
   good book", "comprises a nice historical overview and a chapter about NN
   hardware. Well structured prose. Makes important concepts clear."

   McClelland, J. L. and Rumelhart, D. E. (1988). Explorations in Parallel
   Distributed Processing: Computational Models of Cognition and Perception
   (software manual). The MIT Press. Comments: "Written in a tutorial style,
   and includes 2 diskettes of NN simulation programs that can be compiled on
   MS-DOS or Unix (and they do too !)"; "The programs are pretty reasonable as
   an introduction to some of the things that NNs can do."; "There are *two*
   editions of this book. One comes with disks for the IBM PC, the other comes
   with disks for the Macintosh".

   McCord Nelson, M. and Illingworth, W.T. (1990). A Practical Guide to
   Neural Nets. Addison-Wesley Publishing Company, Inc. (ISBN
   0-201-52376-0). Comments: "No formulas at all"; "It does not have much
   detailed model development (very few equations), but it does present many
   areas of application. It includes a chapter on current areas of research. A
   variety of commercial applications is discussed in chapter 1. It also includes a
   program diskette with a fancy graphical interface (unlike the PDP diskette)".

   Muller, B. and Reinhardt, J. (1990). Neural Networks, An Introduction.
   Springer-Verlag: Berlin Heidelberg New York (ISBN: 3-540-52380-4 and
   0-387-52380-4). Comments: The book was developed out of a course on
   neural-network models with computer demonstrations that was taught by the
   authors to Physics students. The book comes together with a PC-diskette. The
   book is divided into three parts: (1) Models of Neural Networks; describing
   several architectures and learning rules, including the mathematics. (2)
   Statistical Physics of Neural Networks; "hard-core" physics section
   developing formal theories of stochastic neural networks. (3) Computer Codes;
   explanation about the demonstration programs. First part gives a nice
   introduction into neural networks together with the formulas. Together with
   the demonstration programs a 'feel' for neural networks can be developed.

   Orchard, G.A. & Phillips, W.A. (1991). Neural Computation: A Beginner's
   Guide. Lawrence Earlbaum Associates: London. Comments: "Short
   user-friendly introduction to the area, with a non-technical flavour.
   Apparently accompanies a software package, but I haven't seen that yet".

   Rao, V.B & H.V. (1993). C++ Neural Networks and Fuzzy Logic. MIS:Press,
   ISBN 1-55828-298-x, US $45 incl. disks. "Probably not 'leading edge' stuff
   but detailed enough to get your hands dirty!"

   Wasserman, P. D. (1989). Neural Computing: Theory & Practice. Van
   Nostrand Reinhold: New York. (ISBN 0-442-20743-3) Comments:
   "Wasserman flatly enumerates some common architectures from an engineer's
   perspective ('how it works') without ever addressing the underlying
   fundamentals ('why it works') - important basic concepts such as clustering,
   principal components or gradient descent are not treated. It's also full of
   errors, and unhelpful diagrams drawn with what appears to be PCB board
   layout software from the '70s. For anyone who wants to do active research in
   the field I consider it quite inadequate"; "Okay, but too shallow"; "Quite easy
   to understand"; "The best bedtime reading for Neural Networks. I have given
   this book to numerous colleagues who want to know NN basics, but who never
   plan to implement anything. An excellent book to give your manager."

   Wasserman, P.D. (1993). Advanced Methods in Neural Computing. Van
   Nostrand Reinhold: New York (ISBN: 0-442-00461-3). Comments: Several
   neural network topics are discussed e.g. Probabilistic Neural Networks,
   Backpropagation and beyond, neural control, Radial Basis Function Networks,
   Neural Engineering. Furthermore, several subjects related to neural networks
   are mentioned e.g. genetic algorithms, fuzzy logic, chaos. Just the
   functionality of these subjects is described; enough to get you started. Lots of
   references are given to more elaborate descriptions. Easy to read, no extensive
   mathematical background necessary.


   3.  Dedicated Neural Network Journals:

   Title:   Neural Networks
   Publish: Pergamon Press
   Address: Pergamon Journals Inc., Fairview Park, Elmsford, 
            New York 10523, USA and Pergamon Journals Ltd.
            Headington Hill Hall, Oxford OX3, 0BW, England
   Freq.:   10 issues/year (vol. 1 in 1988)
   Cost/Yr: Free with INNS or JNNS or ENNS membership ($45?),
            Individual $65, Institution $175
   ISSN #:  0893-6080
   Remark:  Official Journal of International Neural Network Society (INNS),
            European Neural Network Society (ENNS) and Japanese Neural
            Network Society (JNNS).
            Contains Original Contributions, Invited Review Articles, Letters
            to Editor, Book Reviews, Editorials, Announcements, Software Surveys.

   Title:   Neural Computation
   Publish: MIT Press 
   Address: MIT Press Journals, 55 Hayward Street Cambridge, 
            MA 02142-9949, USA, Phone: (617) 253-2889
   Freq.:   Quarterly (vol. 1 in 1989)
   Cost/Yr: Individual $45, Institution $90, Students $35; Add $9 Outside USA
   ISSN #:  0899-7667
   Remark:  Combination of Reviews (10,000 words), Views (4,000 words)
            and Letters (2,000 words).  I have found this journal to be of
            outstanding quality.
            (Note: Remarks supplied by Mike Plonski "plonski@aero.org")

   Title:   IEEE Transactions on Neural Networks
   Publish: Institute of Electrical and Electronics Engineers (IEEE)
   Address: IEEE Service Cemter, 445 Hoes Lane, P.O. Box 1331, Piscataway, NJ,
            08855-1331 USA. Tel: (201) 981-0060
   Cost/Yr: $10 for Members belonging to participating IEEE societies
   Freq.:   Quarterly (vol. 1 in March 1990)
   Remark:  Devoted to the science and technology of neural networks
            which disclose significant  technical knowledge, exploratory
            developments and applications of neural networks from biology to
            software to hardware.  Emphasis is on artificial neural networks.
            Specific aspects include self organizing systems, neurobiological
            connections, network dynamics and architecture, speech recognition,
            electronic and photonic implementation, robotics and controls.
            Includes Letters concerning new research results.
            (Note: Remarks are from journal announcement)

   Title:   International Journal of Neural Systems
   Publish: World Scientific Publishing
   Address: USA: World Scientific Publishing Co., 1060 Main Street, River Edge,
            NJ 07666. Tel: (201) 487 9655; Europe: World Scientific Publishing
            Co. Ltd., 57 Shelton Street, London WC2H 9HE, England.
            Tel: (0171) 836 0888; Asia: World Scientific Publishing Co. Pte. Ltd.,
            1022 Hougang Avenue 1 #05-3520, Singapore 1953, Rep. of Singapore
            Tel: 382 5663.
   Freq.:   Quarterly (Vol. 1 in 1990)
   Cost/Yr: Individual $122, Institution $255 (plus $15-$25 for postage)
   ISSN #:  0129-0657 (IJNS)
   Remark:  The International Journal of Neural Systems is a quarterly
            journal which covers information processing in natural
            and artificial neural systems. Contributions include research papers,
            reviews, and Letters to the Editor - communications under 3,000
            words in length, which are published within six months of receipt.
            Other contributions are typically published within nine months.
            The journal presents a fresh undogmatic attitude towards this
            multidisciplinary field and aims to be a forum for novel ideas and
            improved understanding of collective and cooperative phenomena with
            computational capabilities.
            Papers should be submitted to World Scientific's UK office. Once a
            paper is accepted for publication, authors are invited to e-mail
            the LaTeX source file of their paper in order to expedite publication.

   Title:   International Journal of Neurocomputing
   Publish: Elsevier Science Publishers, Journal Dept.; PO Box 211;
            1000 AE Amsterdam, The Netherlands
   Freq.:   Quarterly (vol. 1 in 1989)
   Editor:  V.D. Sanchez A.; German Aerospace Research Establishment;
            Institute for Robotics and System Dynamics, 82230 Wessling, Germany.
            Current events and software news editor: Dr. F. Murtagh, ESA,
            Karl-Schwarzschild Strasse 2, D-85748, Garching, Germany,
            phone +49-89-32006298, fax +49-89-32006480, email fmurtagh@eso.org

   Title:   Neural Processing Letters
   Publish: D facto publications
   Address: 45 rue Masui; B-1210 Brussels, Belgium
            Phone: (32) 2 245 43 63;  Fax: (32) 2 245 46 94
   Freq:    6 issues/year (vol. 1 in September 1994)
   Cost/Yr: BEF 4400 (about $140)
   ISSN #:  1370-4621
   Remark:  The aim of the journal is to rapidly publish new ideas, original
            developments and work in progress.  Neural Processing Letters
            covers all aspects of the Artificial Neural Networks field.
            Publication delay is about 3 months.
            FTP server available: 
             ftp://ftp.dice.ucl.ac.be/pub/neural-nets/NPL.
            WWW server available: 
               http://www.dice.ucl.ac.be/neural-nets/NPL/NPL.html

   Title:   Neural Network News
   Publish: AIWeek Inc.
   Address: Neural Network News, 2555 Cumberland Parkway, Suite 299,
            Atlanta, GA 30339 USA. Tel: (404) 434-2187
   Freq.:   Monthly (beginning September 1989)
   Cost/Yr: USA and Canada $249, Elsewhere $299
   Remark:  Commericial Newsletter

   Title:   Network: Computation in Neural Systems
   Publish: IOP Publishing Ltd
   Address: Europe: IOP Publishing Ltd, Techno House, Redcliffe Way, Bristol 
            BS1 6NX, UK; IN USA: American Institute of Physics, Subscriber
            Services 500 Sunnyside Blvd., Woodbury, NY  11797-2999
   Freq.:   Quarterly (1st issue 1990)
   Cost/Yr: USA: $180,  Europe: 110 pounds
   Remark:  Description: "a forum for integrating theoretical and experimental
            findings across relevant interdisciplinary boundaries."  Contents:
            Submitted articles reviewed by two technical referees  paper's 
            interdisciplinary format and accessability."  Also Viewpoints and 
            Reviews commissioned by the editors, abstracts (with reviews) of
            articles published in other journals, and book reviews.
            Comment: While the price discourages me (my comments are based
            upon a free sample copy), I think that the journal succeeds
            very well.  The highest density of interesting articles I
            have found in any journal. 
            (Note: Remarks supplied by kehoe@csufres.CSUFresno.EDU)

   Title:   Connection Science: Journal of Neural Computing, 
            Artificial Intelligence and Cognitive Research
   Publish: Carfax Publishing
   Address: Europe: Carfax Publishing Company, P. O. Box 25, Abingdon, 
            Oxfordshire  OX14 3UE, UK.  USA: Carafax Publishing Company,
            85 Ash Street, Hopkinton, MA 01748
   Freq.:   Quarterly (vol. 1 in 1989)
   Cost/Yr: Individual $82, Institution $184, Institution (U.K.) 74 pounds

   Title:   International Journal of Neural Networks
   Publish: Learned Information
   Freq.:   Quarterly (vol. 1 in 1989)
   Cost/Yr: 90 pounds
   ISSN #:  0954-9889
   Remark:  The journal contains articles, a conference report (at least the 
            issue I have), news and a calendar.
            (Note: remark provided by J.R.M. Smits "anjos@sci.kun.nl")

   Title:   Sixth Generation Systems (formerly Neurocomputers)
   Publish: Gallifrey Publishing
   Address: Gallifrey Publishing, PO Box 155, Vicksburg, Michigan, 49097, USA
            Tel: (616) 649-3772, 649-3592 fax
   Freq.    Monthly (1st issue January, 1987)
   ISSN #:  0893-1585
   Editor:  Derek F. Stubbs
   Cost/Yr: $79 (USA, Canada), US$95 (elsewhere)
   Remark:  Runs eight to 16 pages monthly. In 1995 will go to floppy disc-based
   publishing with databases +, "the equivalent to 50 pages per issue are
   planned." Often focuses on specific topics: e.g., August, 1994 contains two
   articles: "Economics, Times Series and the Market," and "Finite Particle
   Analysis - [part] II."  Stubbs also directs the company Advanced Forecasting
   Technologies. (Remark by Ed Rosenfeld: ier@aol.com)

   Title:   JNNS Newsletter (Newsletter of the Japan Neural Network Society)
   Publish: The Japan Neural Network Society
   Freq.:   Quarterly (vol. 1 in 1989)
   Remark:  (IN JAPANESE LANGUAGE) Official Newsletter of the Japan Neural 
            Network Society(JNNS)
            (Note: remarks by Osamu Saito "saito@nttica.NTT.JP")

   Title:   Neural Networks Today
   Remark:  I found this title in a bulletin board of october last year.
            It was a message of Tim Pattison, timpatt@augean.OZ
            (Note: remark provided by J.R.M. Smits "anjos@sci.kun.nl")

   Title:   Computer Simulations in Brain Science

   Title:   Internation Journal of Neuroscience

   Title:   Neural Network Computation 
   Remark:  Possibly the same as "Neural Computation"

   Title:   Neural Computing and Applications
   Freq.:   Quarterly
   Publish: Springer Verlag
   Cost/yr: 120 Pounds
   Remark:  Is the journal of the Neural Computing Applications Forum.
            Publishes original research and other information
            in the field of practical applications of neural computing.

 


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