/*
 * @(#)$Id: minus,v 1.1 1994/09/16 09:37:56 dream Exp $
 *
 * $Log: minus,v $
 * Revision 1.1  1994/09/16 09:37:56  dream
 * Initial revision
 *
 */

minus(x,y)<==>p_ind(y,x,[~,prev,pred(prev)]).
