
Effective 11 May 1992, domestic and foreign availability of the AutoClass III 
program is only through COSMIC, NASA's software distribution agency.

Request "AutoClass III - Automatic Class Discovery from Data (ARC-13180)".

COSMIC
University of Georgia
382 East Broad Street
Athens, GA  30602  USA
voice: (706) 542-3265  fax: (706) 542-4807
telex: 41- 190 UGA IRC ATHENS
e-mail:	cosmic@@uga.bitnet  or service@@cossack.cosmic.uga.edu								    
	or Tom H. Broom tom@cosmic.cosmic.uga.edu

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

If you have any questions about the procedures, please contact:

Will Taylor		
e-mail: taylor@@ptolemy.arc.nasa.gov
voice: (415)604-3364
fax: (415)604-3594

----------------------------------------------------------------------
ARC-13180 - AutoClass: Automatic Class Discovery from Data
-------------------------------------------------------------
The standard approach to classification in much of artificial
intelligence and statistical pattern recognition research
involves partitioning of the data into separate subsets, known as
classes.  AUTOCLASS III, from NASA Ames Research Center, uses the
Bayesian approach in which classes are described by probability
distributions over the attributes of the objects, specified by a
model function and its parameters.  The calculation of the
probability of each object's membership in each class provides a
more intuitive classification than absolute partitioning
techniques.

AUTOCLASS III is applicable to most data sets consisting of
independent instances, each described by a fixed length vector of
attribute values.  An attribute value may be a number, one of a
set of attribute specific symbols, or omitted.  The user
specifies a class probability distribution function by
associating attribute sets with supplied likelihood function
terms.  AUTOCLASS then searches in the space of class numbers and
parameters for the maximally probable combination.  It returns
the set of class probability function parameters, and the class
membership probabilities for each data instance.

AUTOCLASS III, ARC-13180, is written in Common Lisp, and is
designed to be platform independent.  This program has been
successfully run on Symbolics and Explorer Lisp machines.  It has
been successfully used with the following implementations of
Common LISP on the Sun: Franz Allegro CL, Lucid Common Lisp, and
Austin Kyoto Common Lisp and similar UNIX platforms; under the
Lucid Common Lisp implementations on VAX/VMS v5.4, VAX/Ultrix
v4.1, and MIPS/Ultrix v4, rev. 179; and on the Macintosh personal
computer.  The minimum Macintosh required is the IIci.  This
program will not run under CMU Common Lisp or VAX/VMS DEC Common
Lisp.  A minimum of 8Mb of RAM is required for Macintosh
platforms and 16Mb for workstations.  The standard distribution
medium for this program is a .25 inch streaming magnetic tape
cartridge in UNIX tar format.  It is also available on a 3.5 inch
diskette in UNIX tar format and a 3.5 inch diskette in Macintosh
format.  An electronic copy of the documentation is included on
the distribution medium.  Program $900; documentation $21.
----------------------------------------------------------------------
