1 665c255d 2023-08-04 jrmu (defun powerset (s)
2 665c255d 2023-08-04 jrmu   (if (null s)
3 665c255d 2023-08-04 jrmu       (list nil)
4 665c255d 2023-08-04 jrmu       (let ((rest (powerset (cdr s))))
5 665c255d 2023-08-04 jrmu 	(append
6 665c255d 2023-08-04 jrmu 	 rest
7 665c255d 2023-08-04 jrmu 	 (mapcar (lambda (r)
8 665c255d 2023-08-04 jrmu 		   (cons (car s) r))
9 665c255d 2023-08-04 jrmu 		 rest)))))