On 5/31/07, Lt. Castillo <trequer@hotmail.com> wrote:

Hi all:
I have a question about ID3 algorithm (sorry my english). Some documentation I read said that an atribut can't appear more than once in the tree.

Yes, I think this is correct. Because once you select an attribute at a node, you split the instances.
For the split instances, the gain will be zero for the same attribute. This will be true for the entire subtree below the node, so I think you will not have the same attribute appearing more than once in the tree.

But in weka I saw atributes that appear several times in a tree. My question is:
this happen because of weka is not using ID3 algorithm (I'm using J48-similiar to C4.5, I think) or is because of only the most pure form of ID3 don't allow an atribute to appear more than once in a tree?

Weka does have a seperate ID3 implementation in weka.classifiers.trees.

Devendra Laulkar

May the Source be with you.