Decision Tree and Genie Equivalent

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Gardiola
Posts: 29
Joined: Mon Mar 11, 2013 4:38 pm

Decision Tree and Genie Equivalent

Post by Gardiola »

Good Morning All,

I would like to create the equivalent of a decision tree with value maximixation.

Each node of tree, there's a random variable related to a decision variables.

By construction, a tree equivalent looks like a linear model where all the probability has to reflect the potential branching.
The final node is the financial gain utility.

My understanding is correct ? do I miss some concepts ?

The nested decision will give the optimun value in the value node.

Do you have any exemple of decision tree ?

Thanks for this .

Didier
marek [BayesFusion]
Site Admin
Posts: 430
Joined: Tue Dec 11, 2007 4:24 pm

Re: Decision Tree and Genie Equivalent

Post by marek [BayesFusion] »

Didier,

GeNIe and SMILE do not implement decision trees and this is by design -- we decided that for the types of applications that we had in mind (building complex decision support systems), it was not worth it.

Influence diagrams, which are implemented in GeNIe and SMILE, are almost equivalent to decision trees and you can represent a decision problem in each of the two. You can even translate a decision tree to an influence diagram and back. Now, the differences. For every tree, there is one unique equivalent influence diagram (ID). For every ID, there are possibly multiple trees. The reason for that is that a tree imposes a total order on its nodes, while a directed graph underlying an ID only a partial order. Trees are handier in implementing asymmetric decision problems and when small enough, may be more intuitive for humans. On the other hand, they grow exponentially, they are poor in showing independences and causal relations. If you want to understand the relationship between trees and IDs, please look at Clemen's book (listed in the reference list) and GeNIe IDs for the book on our web site. I will be glad to draw an ID for you if you send me your tree (hand-drawn is just fine, but please do make sure that you have all the numbers in it).
I hope this helps.

Marek
Gardiola
Posts: 29
Joined: Mon Mar 11, 2013 4:38 pm

Re: Decision Tree and Genie Equivalent

Post by Gardiola »

Marek

It helps

Thanks

Didier
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