The ``subtraction world'' is a software package that includes a Tcl/Tk graphical interface reprenting a ``blackboard'' on which to do multi-column subtraction problems, together with a reimplementation of Brown and VanLehn's ``repair theory'' within the Soar cognitive architecture.
The code and other materials were originally developed by Randolph M. Jones, Peter M. Wiemer-Hastings, and John E. Laird, at the Artificial Intelligence Laboratory of the University of Michigan. Subsequent versions were created by Randolph M. Jones, while at Colby College and Soar Technology, Inc.
Below you can see a picture of the interface. When time permits, this document will fill in more information on the subtraction world and the courses it has been used for.
The most recent version of the subtraction world is 2.0.
To use subtraction world version 2.0, you will need Soar Version 7.2, which is available from the Soar Software Page.
