(defklass node ()
  name
  description
  priority ; how much to stres on achieving this one
  ;givens ; distributions
  ;goals ; distributions
  computeds; distributions
  ;costs; distributions whose y-axis is the cost
  lockedp ; locked or free
  cost ; (of controlling)
  tags ; (from classes)
)   
(defklass scenaro ()
	graph
	view
	lockeds
	goals
	givens
	costs
)
(defklass views ()
	user
	likes
	dislikes
)

(defklass graph ()
	name
	nodes
)
(defmethod leafp ((n nodes))
	(not (nodes-kids n)))
(defklass distribution
   buckets ; ordered list of value.height pairs
   min
   max
)
	
(defklass nodes node kids)        
(defklass andv  nodes) 
(defklass orv   nodes)
(defklass notv  nodes )
(defklass nullv  nodes )
  
(defmethod ? ((n null))   (error "null lookup"))
(defmethod ? ((n symbol)) (? (at n)))
(defmethod ? ((n node))   (or (node-got n) (sample n)))

(defmethod ! ((n null))   (error "null setting"))
(defmethod ! ((n symbol)) (! (at n)))
(defmethod ! ((n node))   (setf (node-got n) (? n)))

(defmethod combine ((a andv)) #'least)
(defmethod combine ((a orv)) #'most)