[CM] pval in markov

Rick Taube taube@uiuc.edu
Wed, 16 Mar 2005 09:47:12 -0600

> Was wondering if perhaps I am misunderstanding something about pval.

assuming that you are trying to get dynamic weights, ie weights that 
change as the pattern evolves, then no you are not misunderstanding 
anything -- this is a long standing
misfeature of the markov pattern. actually im going over all the 
pattern stuff (and rewriting/updating the pattern documentation) right 
now, ill see if i can do something about this while im at it.

> Now, the following does work:
> (setf x (new markov :of `((50 -> (51 ,(funcall (pval-thunk (pval 
> (between .2 1.0))))) (50 .1))
> 			  (51 -> (50 ,(funcall (pval-thunk (pval (between .2 1.0))))) (51 
> .1)))))

this wont do what you want -- the value of your funcall is a constant, 
not a pval.

if you want a workaround for now, since you are doing 1st order markov  
you can use the graph pattern instead:

(new graph :of `((50 :to ,(new random :of `((51 :weight ,(pval (between 
.2 1.0))) (50 :weight .1))))
                            (51 :to ,(new random :of `((50 :weight 
,(pval (between .2 1.0))) (51 :weight .1))))))