================ Symbolic Pattern Associator (V1.0) ================

spa.c is a general purpose symbolic pattern associator that learns
mapping from N input attributes (discrete or numerical) to M output 
attributes (discrete only). The program builds M decision trees
using a modified version of Quinlan's C4.5 (Release 2).

One specific purpose for this is to learn mappings from 
English verb stems to their past tenses, and compare the results
with connectionist models. See files under directory "data". It has been
demostrated that SPA is a better learning model for past-tense acquision.

Designer:    Charles X. Ling
Programmers: Steven Cherwenka, Huaqing Zeng
Contact: ling@csd.uwo.ca   1-519-661-3341 (o), -3515 (fax)

================ Copyright ================
The SPA can be freely used and distributed for research purpose only.

If you publish results from the SPA, I'd appreciate you let me know
first... just to make sure that the SPA is set-up and used properly.

================ Major Contributions on SPA ================
An easy-to-use N-to-M decision tree learning algorithm.

A new default strategy for the tree learning algorithms. See JAIR paper.

c4.5rules has been modified so it produces longest rules first before
shorter ones. See Cognition paper.

================ How to make it work ================
======= NOTE: SPA uses a modified version of C4.5 (Release 2), and 
	I discovered recently that C4.5 is copyrighted. For info on
	C4.5, contact Ross Quinlan: quinlan@ml2.cs.su.oz.au
	So I can only give the excutable, not the source codes. I have 
	compiled the codes on Sun 4, and left the excutables in the 
	directory data/. 
	If you need to run the SPA on other machine, let me know and
	I will try to compile it for you.

ftp ftp.csd.uwo.ca
login: anonymous
password: <your ident>
ftp> cd pub/SPA
ftp> get Readme.spa        [this file]
ftp> binary
ftp> get SPA.tar.Z
ftp> quit
uncompress SPA.tar.Z
tar xvf SPA.tar            [create SPA/data, SPA/src]
cd SPA/src
make 
cd ../data
more Readme

The codes have been tested successfully on Sun3 and Sun4.

================ Relevant papers ================
Postscript files of these two papers are kept under SPA/paper/ at our ftp site.

Ling, X., & Marinov, M. Answering the connectionist challenge.  
Cognition, 49 (3), 235--290. 1993. See SPA/papers/cognition-verb.ps

Ling, X. Symbolic pattern associator. Journal of Artificial Intelligence 
Research 1. 209--229. 1994. See SPA/papers/jair-verb.ps