[R] learning networks with a large number of variables and pre-set parents.

[zhihua li]

hi netters: 

I have a series of  discrete variables which form a network and  I want to 
learn the network structure from some training data. I could have used 
packages like deal but there are two problems. 

First of all, I have 10000 variables. So the possible network structure is 
awfully huge, I don't know how long it will take my PC to find the 
highest-scoring network..........maybe a month? 
Secondly, I have some prior knowledge that only 500 out of the 10000 
variales are possible parents. In another word, only those arrows startting 
from the 500 variables and pointing to the remaining 99500 variables are 
allowed in the network.  In deal an assignment to "banlist" should help me 
rule out the impossible arrows. But in my case the number of "impossible 
arrows" is  500*499+99500*99549, and so the "banlist" would get 
unacceptable long. Are there any methods (in deal or other packages) to 
specify the parents set in advance? 

Thanks a lot!