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C00006 00004	STAN-CS-79-691  THE CONSTRUCTION OF INITIAL DATA FOR HYPERBOLIC SYSTEMS 
C00010 00005	HPP-77-39  MODELS OF LEARNING SYSTEMS
C00012 00006	STAN-CS-79-693  A CLASS OF SOLUTIONS TO THE GOSSIP PROBLEM
C00014 00007	STAN-CS-79-694  COMPUTER SCIENCE AT STANFORD, 1977-1978
C00016 00008	AIM-321  RECENT RESEARCH IN ARTIFICIAL INTELLIGENCE AND FOUNDATIONS 
C00017 00009	HPP-78-22  CONSIDERATIONS FOR MICROPROCESSOR-BASED TERMINAL DESIGN
C00020 00010	STAN-CS-79-697  ON THE LINEAR LEAST SQUARES PROBLEM WITH A QUADRATIC 
C00022 00011	STAN-CS-79-698  IMPERICAL ESTIMATES OF PROGRAM ENTROPY
C00025 00012	HPP-78-23  SACON: A KNOWLEDGE-BASED CONSULTANT FOR STRUCTURAL ANALYSIS
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MOST RECENT CS REPORTS - JANUARY 1979

@Listed below are abstracts of the most recent reports published by the Computer
Science Department of Stanford University.

@TO REQUEST REPORTS:  Check the appropriate places on the enclosed order form,
and return the entire order form page (including mailing label) by January 26, 1979.
In many cases we can print only a limited number of copies, and requests will
be filled on a first come, first serve basis.  If the code (FREE) is printed
on your mailing label, you will not be charged for hardcopy.  This exemption
from payment is limited primarily to libraries.  (The costs shown include all
applicable sales taxes.  PLEASE SEND NO MONEY NOW, WAIT UNTIL YOU GET AN 
INVOICE.)

@ALTERNATIVELY:  Copies of most Stanford CS Reports may be obtained by writing
(about 2 months after MOST RECENT CS REPORTS listing) to NATIONAL TECHNICAL
INFORMATION SERVICE, 5285 Port Royal Road, Springfield, Virginia 22161.  Stanford
Ph.D. theses are available from UNIVERSITY MICROFILMS, 300 North Zeeb Road,
Ann Arbor, Michigan 48106.
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STAN-CS-79-691  THE CONSTRUCTION OF INITIAL DATA FOR HYPERBOLIC SYSTEMS 
		FROM NONSTANDARD DATA
Author:  Kenneth P. Bube↔(Thesis)
.end
@Abstract:  We study the first order systems of hyperbolic partial differential
equations with periodic boundary conditions in the space variables for which
complete initial data are not available.  We suppose that we can measure
u↑I , the first j components of a solution u of the system, perhaps
with its time derivatives, but cannot measure u∩[II] , the rest of the
components of u , completely and accurately at any time level.  Such problems
arise in geophysical application where satelites are used to collect data.
We consider two questions.  How much information do we need to determine the
solution u uniquely in a way which depends continuously on the data?  How
do we use these data compuationally to obtain complete initial data at some
time level?

@We investigate several approaches to answering these questions.  We show that
under certain hypotheses u∩[II] at the initial time is determined uniquely
by and depends continuously on the data obtained by measuring either u↑I over
a whole time interval or u↑I and its first time derivative at the initial
time, together ith either u∩[II] on a hyperplane in space of one lower
dimension or a finite number of Fourier coefficients of u∩[II] at
the initial time.  Our results demonstrate that it is possible to reduce the
data requirements of u∩[II] if sufficient information about u↑I is
available.

@One appliction we examine is the effect of the Coriolis term in the linearized
shallow water equations on the possibility of recovering the wind fields from
the geopotential height.

@We present algorithms and computational results for these approaches for a model
two-by-two system, and examine the method for intermittent updating currently
being used in numerical weather prediction as a method for the assimilation of
data.  Our results suggest that the use of different frequencies of updating
is important to avoid slow convergence.
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No. of pages:  119
Available in microfiche only.
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HPP-77-39  MODELS OF LEARNING SYSTEMS
Authors:  Bruce G. Buchanan, Tom M. Mitchell, Reid G. Smith 
	  & C. Richard Johnson Jr.
.end
@Abstract:  The terms adaptation, learning, concept-formation, induction,
self-organization, and self-repair have all been used in the context of learning
system (LS) research.  In this article, three distinct approaches to machine
learning and adaptation are considered:  (i) the adaptive control approach,
(ii) the pattern recognition approach, and (iii) the artificial intelligence
approach.

@Progress in each of these areas is summarized in the first part of the article.
In the next part a general model for learning systems is presented that allows
characterization and comparison of individual algorithms and programs in all these
areas.  The model details the functional components felt to be essential for any
learning system, independent of the techniques used for its construction, and the
specific environment in which it operates.  Specific examples of learning systems
are described in terms of the model.
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No. of pages:  38
Cost:  $ 2.80
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STAN-CS-79-693  A CLASS OF SOLUTIONS TO THE GOSSIP PROBLEM
Author:  Douglas B. West
.end
@Abstract:  We characterize and count optimal solutions to the gossip
problem in which no one hears his own information.  That is, we consider graphs
with n vertices where the edges have a linear ordering such that an
increasing path exists from each vertex to every other, but there is no
increasing path from any vertex to itself.  Such graphs exist only when n
is even, in which case the fewest number of edges is 2n-4, as in the original
gossip problem.  We characterize optimal solutions of this sort (NOHO-graphs)
using a correspondence with a set of permutations and binary sequences.  This
correspondence enables us to count these solutions and several subclasses of
solutions.  The numbers of solutions in each class are simple powers of 2
and 3, with exponents determined by n.  We also show constructively that
NOHO-graphs are planar and Hamiltonian, and we mention applications to related
problems.
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No. of pages:  61
Cost:  $ 3.45
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STAN-CS-79-694  COMPUTER SCIENCE AT STANFORD, 1977-1978
Editor:  Jonathan King
.end
@Abstract:  This report is a review of Stanford Computer Science Department 
activities for the academic year 1977-78.  The report includes:##
(1) The Chairman's overview of the important events of the 
year, (2) Recent activities and interests of faculty members and 
research associates arranged by research specialty,
(3) Advanced doctoral students in each specialty and their research topics,
(4) Recipients of M.S. and Ph.D. degrees,
(5) Speakers at seminar and colloquia series, and
(6) Bibliography of Computer Science Department technical reports.
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No. of pages:  27
Cost:  $ 2.50
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AIM-321  RECENT RESEARCH IN ARTIFICIAL INTELLIGENCE AND FOUNDATIONS 
	 OF PROGRAMMING
Authors:  Lester Earnest et al.
.end
@Abstract:  Summarizes recent research in the following areas:  artificial
intelligence and formal reasoning, mathematical theory of computation and
program synthesis, program verification, image understanding, and knowledge
based programming.
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No. of pages:  94
Cost:  $ 4.35
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HPP-78-22  CONSIDERATIONS FOR MICROPROCESSOR-BASED TERMINAL DESIGN
Authors:  Reid G. Smith & Tom M. Mitchell
.end
@Abstract:  We discuss the design of hardware and software for inexpensive
microprocessorr-based terminal/microcomputers.  Such devices are fundamentally
microcomputers that have been adapted, with specialized software, to operate as
remote terminals for a host compuer.

@The discussion centers on a specific video terminal designed and constructed
by the authors.  This terminal is based on the INTEL 8080 microprocessor and is
equipped with software sufficient to emulate the characteristics of standard
video terminals required by several available SCREEN-ORIENTED text editors
in common use at sites throughout the ARPAnet.

@We have found that the microprocessor adequately serves as the controller for
such terminals, and that a SOFTWARE-BASED approach to the design of such
terminals offers substantial advantages in capabilities, flexibility, and cost
over the HARDWARE-BASED approach.  We suggest guidelines for future designs
of microprocessor-based terminals on the basis of our experience designing and
using the terminal described here.

In order to take full advantage of the flexibility afforded by microprocessor-based
designs, we have implemented the capability to DOWNLOAD and execute 8080
programs written and assembled on a host computer.  This allows the user to
customize and extend the microcomputer with the software development tools and
mass storage provided by the host computer.  The terminal is thus a complete,
stan-alone microcomputer system specially configured for its role as a terminal.
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No. of pages:  14
Cost:  $ 2.10
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STAN-CS-79-697  ON THE LINEAR LEAST SQUARES PROBLEM WITH A QUADRATIC 
		CONSTRAINT
Author:  Walter Gander
.end
@Abstract:  In this paper we present the theory and practical computational
aspects of the linear least squares problem with a quadratic constraint.  New
theorems characterizing properties of the solutions are given and extended for
the problem of minimizing a general quadratic function subject to a quadratic
constraint.  For two important regularization methods we formulate dual equations
which proved to be very useful for the application os smoothing of datas.  The
resulting algorithm is a numerically stable version of an algorithm proposed by
Ruthishauser.  We show also how to choose a third order iteration method to solve
the secular equation.  However we are still far away from a foolproof machine
independent algorithm.
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No. of pages:  120
Available in microfiche only.
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STAN-CS-79-698  IMPERICAL ESTIMATES OF PROGRAM ENTROPY
Author:  Richard E. Sweet↔(thesis)
.end
@Abstract:  With the trend toward small computers, there is an increased
emphasis on compact object programs.  This can be accomplished by
using an encoding that is specialized for a given programming
language.  This thesis explores the question of a lower bound for
the size of an encoding for "typical" programs.  The approach is to
apply the principles of information theory to an empirical sample of
programs.  A collection of 114 Mesa programs, comprising
approximately a million characters of source text, is analyzed.

@The representation of programs used for analysis is that of trees. 
The concept of a Markov source is defined for trees in several ways,
and the entropy of these sources is estimated.  A Markov source of
non-uniform order is defined, which has better empirical
characteristics for the tree sources, and can also be useful for
standard sequential sources.  For the Mesa sample studied, an
information content of approximately one half bit per character of
source is estimated.  In addition, the tree data can be used to
address several questions of programming style and static variable
usage.
.begin nofill
No. of pages:  167
Cost:  $ 6.40
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HPP-78-23  SACON: A KNOWLEDGE-BASED CONSULTANT FOR STRUCTURAL ANALYSIS
Authors:  James Bennet, Lewis Creary, Robert Englemore & Robert Melosh
.end
@Abstract:  In this report we describe an application of artificial
intelligence (AI) methods to structural analysis.  We describe the development
and (partial) implementation of an "automated consultant" to advise non-expert
engineers in the use of a general-purpose structural analysis program.  The
analysis program numerically simulates the behavior of a consultant, called
SACON (Structural Analysis CONsultant), is based on a version of the MYCIN
program [Shortliffe 74], originally developed to advise physicians in the
diagnosis and treatment of infectious deseases.  The domain-specific knowledge
in MYCIN is represented as situation-action rules, and is kept independent of
the "inference engine" that uses the rules.  By substituting structural
engineering knowledge for the medical knowledge, the program was converted
easily from the domain of infectious diseases to the domain of structural
analysis.
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No. of pages:  65
Cost:  $ 3.55
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Available from
Stanford Systems Optimization Laboratory
.end
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SOL 78-19  A BIDIAGONALIZATION ALGORITHM FOR SPARSE LINEAR EQUATIONS AND
	   LEAST-SQUARES PROBLEMS
Authors:  Christopher C. Paige & Michael A. Saunders
.end
@Abstract:  A method is given for solving Ax = b and 
min||Ax-b||↓2 where the matrix A is large and sparse.  The method
is based on the bidiagonalization procedure of Golub and Kahan.  It is
analytically equivalent to the method of conjugate gradients (CG) but possesses
more favorable numerical properties.  The Fortran implementation of the method
(subroutine LSQR) incorporates reliable stopping criteria and provides
estimates of various quantities including standard errors for x and the
condition number of A.  Numerical tests are described comparing LSQR with
several other CG algorithms.  Further results for a large practical problem
illustrate the effect of pre-conditioning least-squares problems using a sparse
LU factorization of A.

Available by writing directly to:  Gail L. Stein, Systems Optimization Laboratory,
Department of Operations Research, Stanford University, Stanford, California
94305 U.S.A.
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