subset of features after each split

[glycerine]

Hi Ryan -- this looks like a great project. I'm a big fan of Go.

I would like to restrict the features (a.k.a. the independent variables available for the next split) to a particular subset after each split/decision node in the CART tree. The features available after the first split would depend upon the feature chosen first.

Could you advise which files I should study to add the feature described above?

Thank you!

Jason