COMMENT ⊗   VALID 00012 PAGES
C REC  PAGE   DESCRIPTION
C00001 00001
C00002 00002	.DEVICE XGP 
C00003 00003	.once center
C00005 00004	STAN-CS-79-710
C00008 00005	STAN-CS-78-711
C00012 00006	STAN-CS-79-712
C00013 00007	STAN-CS-79-713
C00015 00008	AIM-322
C00018 00009	STAN-CS-79-717
C00020 00010	AIM-323
C00021 00011	STAN-CS-79-719
C00023 00012	STAN-CS-79-720
C00024 ENDMK
C⊗;
.DEVICE XGP; 
.
.turn on "↔" for "→"
.turn on "%,π,α,#,&,∂,↑,↓,[,]"
.turn on "∩" for "↑"
.turn on "∪" for "↓"
.
.font 1 "nonm";
.font 2 "baxm30";
.font 3 "math30";
.font 4 "fix25";
.font 5 "grkl30";
.
.sides←1;
.require "twocol.pub[sub,sys]" source file;
.
.SELECT 1
.at "@" ⊂"####"⊃
.at "|cd" ⊂"%3α*%*"⊃
.at "≤" ⊂"%4α≤%*"⊃
.
.at "!!" txt ";"	⊂
.("txt"[1]&"∩["&"txt"[2]&"]&∪[ "&"txt"[3]&"]");
.  ⊃
.
.PLACE TEXT;
.
.next page
.once center
%1MOST RECENT CS REPORTS - JUNE 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
June 29, 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.
.begin nofill
--↔--
--↔--
.end
STAN-CS-79-710
.once preface 0
@NUMERICAL COMPUTATION OF THE SCHWARZ-CHRISTOFFEL TRANSFORMATION

Author:  Lloyd Trefethen

@ABSTRACT:  A program is described which computes Schwarz-Christoffel
transformations that map the unit disk conformally onto the interior of a
bounded or unbounded polygon in the complex plane.  The inverse map is also
computed.  The computational problem is approached by setting up a nonlinear
system whose unknowns are essentially the unknown "accessory parameters" z↓k,
and solving this system with a standard subroutine.

@New features of this work include the evaluation of integrals within the
disk rather than along the boundary, making possible the treatment of unbounded
polygons; the use of a compound form of Gauss-Jacobi quadrature to evaluate the
Schwarz-Christoffel integral, making possible high accuracy at reasonable cost;
and the elimination of constraints in the nonlinear system by a simple change
of variables.

@Application of the Schwarz-Christoffel transformation may lead to practical
methods for solving the Laplace and Poisson equations accurately in two-cimensional
problems with irregular or unbounded (but not curved or multiply connected)
geometrices.  Computational examples are presented.  The time required to solve
the mapping problem is roughly proportional to N↑3, where N is the number of
vertices of the polygon.  A typical set of computations to 8-place accuracy
with N %3≤%1 10 takes 1-10 seconds on an IBM 370/168.
.begin nofill

No. of pages:  42
Cost:  $ 2.90
--↔--
.end
STAN-CS-78-711
.once preface 0
@VERSION SPACES: AN APPROACH TO CONCEPT LEARNING

Author:  Tom Michael Mitchell↔(Thesis)

@ABSTRACT:  A method is presented for learning general descriptions of concepts
from a sequence of positive and negative training instances.  This method involves
examining a predetermined space or language of possible concept descriptions,
finding those which are consistent with the observed training instances.  Rather
than use heuristic search techniques to examine this concept description space,
the subspace (version space) of all plausible concept descriptions is represented
and updated with each training instance.  This version space approach determines
all concept descriptions consistent with the training instances, without backtracking
to reexamine past training instances or previously rejected concept descriptions.

@The computed version space summarizes the information within the training instances
concerning the identity of the concept to be learned.  Version spaces are therefore
useful for making reliable classifications based upon partially learned concepts,
and for proposing informative new training instances to direct further learning.
The uses of version spaces for detecting inconsistency in the training instances,
and for learning in the presence of inconsistency are also described.

@Proofs are given for the correctness of the method for representing version
spaces, and of the associated concept learning algorithm, for any countably
infinite concept description language.  Empirical results obtained from computer
implementations in two domains are presented.  The version space approach has
been implemented as one component of the Meta-DENDRAL program for learning
production rules in the domain of chemical spectroscopy.  Its implementation in
this program is described in detail.
.begin nofill

No. of pages:  216
Cost:  $ 7.75
--↔--
.end
STAN-CS-79-712
.once preface 0
@THE ERRATA OF COMPUTER PROGRAMMING

Author:  Donald E. Knuth

@ABSTRACT:  This report lists all corrections and changes of Volumes 1 and 3 of
%2The Art of Computer Programming%1, as of January 5, 1979.  This updates the
previous list in report CS-551, May 1976.  The second edition of Volume 2 has
been delayed two years due to the fact that it was completely revised and put
into the TEX typesetting language; since publication of this new edition is not
far off, no changes to Volume 2 are listed here.
.begin nofill

No. of pages:  58
Cost:  $ 3.35
--↔--
.end
STAN-CS-79-713
.once preface 0
@A HESSENBERG-SCHUR METHOD FOR THE PROBLEM AX + XB = C

Authors:  Gene Golub, Stephen Nash & Charles Van Loan

@ABSTRACT:  One of the most effective methods for solving the matrix equation
AX + XB = C is the Bartels-Stewart algorithm.  Key to this technique is the
orthogonal reduction of A and B to triangular form using the QR algorithm for
eigenvalues.  A new method is proposed which differes from the Bartels-Stewart
algorithm in that A is only reduced to Hessenberg form.  The resulting algorithm
is between 30 and 70 percent faster depending upon the dimensions of the
matrices A and B.  The stability of the new method is demonstrated through a
roundoff error analysis and supported by numerical tests.  Finally, it is
shown how the techniques described can be applied and generalized to other
matrix equation problems.
.begin nofill

No. of pages:  50
Available in microfiche only.
--↔--
.end
AIM-322
.once preface 0
@A FRAMEWORK FOR CONTROL IN PRODUCTION SYSTEMS

Author:  Michael Georgeff

@Abstract:  A formal model for representing control in production systems is defined.  The
formalism allows control to be directly specified independently of the conflict
resolution scheme, and thus allows the issues of control and nondeterminism to
be treated separately.  Unlike previous approaches, it allows control to be
examined within a uniform and consistent framework.

@It is shown that the formalism provides a basis for implementing control
constructs which, unlike existing schemes, retain all the properties desired
of a knowledge based system --- modularity, flexibility, extensibility and
explanatory capacity.  Most importantly, it is shown that these properties are not
a function of the lack of control constrains, but of the type of information
allowed to establish these constraints.

@Within the formalism it is also possible to provide a meaningful notion of
the power of control constructs.  This enables the types of control required
in production systems to be examined and the capacity of various schemes to
meet these requirements to be determined.

@Schemes for improving system efficiency and resolving nondeterminism are
examined, and devices for representing such meta-level knowledge are described.
In particular, the objectification of control information is shown to provide a
better paradigm for problem solving and for talking about problem solving.
It is also shown that the notion of control provides a basis for a theory of
transformation of production systems, and that this provides a uniform and
consistent approach to problems involving subgoal protection.
.begin nofill

No. of pages:  35
Cost:  $ 2.70
--↔--
.end
STAN-CS-79-717
.once preface 0
@THE PEBBLING PROBLEM IS COMPLETE IN POLYNOMIAL SPACE

Authors:  John R. Gilbert, Thomas Lengauer, & Robert E. Tarjan

@Abstract:  We examine a pebbing problem which has been used to study the
storage requirements of various models of computation.  Sethi has shown this
problem to be NP-hard and Lingas has shown a generalization to be P-space
complete.  We prove the original problem P-space complete by employing a
modificaion of Lingas's proof.  The pebbling problem is one of the few examples
of a P-space complete problem not exhibiting any obvious quantifier alternation.
.begin nofill

No. of pages:  32
Cost:  $ 2.60
--↔--
.end
AIM-323
.once preface 0
@AL USERS' MANUAL

Authors:  Shahid Mujtaba & Ron Goldman

@Abstract:  This document describes the current state of the AL system now 
in operation at the Stanford Artificial Intelligence Laboratory, and
teaches the reader how to use it.  The system consists of AL, a high-level
programming language for manipulator control useful in industrial assembly
research; POINTY, an interactive system for specifying representation of
parts; and ALAID, an interactive debugger for AL.
.begin nofill

No. of pages:  136
Cost:  $ 5.55
--↔--
.end
STAN-CS-79-719
.once preface 0
@EXTRAPOLATION OF ASYMPTOTIC EXPANSIONS BY A MODIFIED AITKEN %5d%1↑2-FORMULA

Authors:  Petter Bj%3O%1rstad, Germund Dahlquist & Eric Grosse

@Abstract:  A modified Aitken formula permits iterted extrapolations to
efficiently estimate %5d%4↓∞%1 from %5d%2↓n%1 when an asymptotic expansion
.skip
.once center
%5d%2↓n%2 = %5d%4↓∞%2 + n∩[-k](c↓0 + c↓1n∩[-1] + c↓2n∩[-2] + ...)%1

holds for some (unknown) coefficients %2c↓j%1.  We study the truncation and
irregular error and compare the method with other forms of extrapolation.
.begin nofill

No. of pages:  
Available in microfiche only.
--↔--
.end
STAN-CS-79-720
.once preface 0
@ON GRID OPTIMIZATION FOR BOUNDARY VALUE PROBLEMS

Author:  R. Glowinski

@Abstract:  We discuss in this report the numerical procedures which can be
used to obtain the optimal grid when solving by a finite element method a model
boundary value problem of elliptic type modelling the potential flow of an
incompressible inviscid fluid.  Results of numerical experiments are presented.
.begin nofill

No. of pages:  22
Available in microfiche only.
--↔--
.end