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LEGAL NOTICE
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American society is growing increasingly litigeous; we regret the
necessity of the following notice.  That is, the copyright notice
below and the paragraph which follows must be included in any separate
copy of the code from this book:

Copyright (c) 1986-1993 Kenneth D. Forbus, Johan de Kleer and Xerox
Corporation.  All Rights Reserved.

Use, reproduction, and preparation of derivative works are permitted.
Any copy of this software or of any derivative work must include the
above copyright notice and this paragraph.  Any distribution of this
software or derivative works must comply with all applicable United
States export control laws.  This software is made available as is, and
Kenneth D. Forbus, Johan de Kleer and Xerox Corporation disclaim all
warranties, express or implied, including without limitation the implied
warranties of merchantability and fitness for a particular purpose, and
notwithstanding any other provision contained herein, any liability for
damages resulting from the software or its use is expressly disclaimed,
whether arising in contract, tort (including negligence) or strict
liability, even if Kenneth D. Forbus, Johan de Kleer or Xerox
Corporation is advised of the possibility of such damages.