(defvar *feature-names* nil
  "Used to make printing of decision trees more readable")


;;; *feature-names* has names of features
(setf *feature-names* '(class outlook temperature humidity windy))

;;;First feature must always be the classification of the example, in
;;;this case, + for good tennis days, - for bad
(setf tennis-examples
      ;; class  outlook temp    humid   windy
      '((-	sunny	hot	high	false)
	(-	sunny	hot	high	true)
	(+	overcast	hot	high	false)
	(+	rain	mild	high	false)
	(+	rain	cool	normal	false)
	(-	rain	cool	normal	true)
	(+	overcast	cool	normal	true)
	(-	sunny	mild	high	false)
	(+	sunny	cool	normal	false)
	(+	rain	mild	normal	false)
	(+	sunny	mild	normal	true)
	(+	overcast	mild	high	true)
	(+	overcast	hot	normal	false)
	(-	rain	mild	high	true)))