Hi, this is a repost of a previous thread (BDe scoring metric). I thought I
would repost it under this title to see if it gets a better response.
Basically I'm looking for an efficient way to calculate the joint of an
arbitrary subset of nodes in a Bayes net. Below is one algorithm I
proposed, but it's not terribly efficient.
Thanks,
Denver.
- ----- Original Message -----
From: "Denver Dash" <ddash@isp.pitt.edu>
To: <uai@CS.ORST.EDU>
Sent: Thursday, March 23, 2000 5:23 PM
Subject: Re: [UAI] BDe scoring metric
> Basically you need to calculate the joint over an arbitrary subset of
> variables: P(V1,V2,...Vm) where m<n (the total number of variables).
>
> One way to do this is to do the following:
>
> Make use of the fact that P(V1,V2,...,Vm) is equal to
> P(V1)P(V2|V1)P(V3|V1,V2)...P(Vm|V1,...,Vn-1).
>
> This suggests the following algorithm to calculate the joint of a subset S
> of nodes:
>
> Evidence_Set = {};
> jointProb = 1;
>
> For each node V in S do:
> Update beliefs in network given Evidence_Set.
> query node V to get P(V|Evidence_Set).
> jointProb = jointProb * P(V|Evidence_Set)
> Evidence_Set += V
>
> Of course if the nodes are in the same clique then you can find a more
> efficient way to calculate their joint (marginalize the potentials over
the
> non-included variables), but in general this won't be the case.
>
> I would also be interested if anybody knows of a more efficient way to do
> this calculation in general.
>
> Cheers,
> Denver.
> --
> Denver Dash http://www.sis.pitt.edu/~ddash
>
> ----- Original Message -----
> From: "Mohamed Bendou" <mohamed@esiea-ouest.fr>
> To: <uai@CS.ORST.EDU>
> Sent: Thursday, March 23, 2000 12:58 PM
> Subject: [UAI] BDe scoring metric
>
>
> > Hi,
> > I try to program the BDe scoring metric for learning bayesian networks.
> > Could you indicate me reference to the algorithmic aspects of
> > calculating priors on parameters?
> > I do not understand how i can calculate efficiently the prior joint
> > probabilities
> > from the prior network.
> >
> > Thank you.
> >
> >
> > Mohamed BENDOU
> >
> >
> > --
> > Mohamed BENDOU
> >
> >
>
------- End of Forwarded Message
This archive was generated by hypermail 2b29 : Thu Mar 30 2000 - 12:25:42 PST