

















   Purpose: "suspicious" negation 

/*  This file defines a version of 'not' wh
checks that there are
    no free variables in the goal it is given to "dis
e".  Bound
    variables introduced by the existential quantifier ^ or 
bag
    dummy variables are accepted.  If any free variables are fo
 
    a message is printed on the terminal and a break level en
d.

    It is intended purely as a debugging aid, though it







































































































rolog 
sh





























































































































































































































































































































































































































































































































































































































































































