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christophM / interpretable-ml-book

Book about interpretable machine learning
https://christophm.github.io/interpretable-ml-book/
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typo on number of rules #232

Closed cmencar closed 2 years ago

cmencar commented 3 years ago

Ch. "INTERPRETABLE MODELS", section "RuleFit", subs. "Theory", subsubs. "step 1". The the number of rules created from an ensemble of M trees should be

K = \sum_{i=1}^M{2^{t_m-1}}

That is, the number of rules grows exponentially with the number of terminal nodes.

christophM commented 2 years ago

The formula is from the original paper, page 7: https://arxiv.org/pdf/0811.1679.pdf

If you go down the tree, there are also many duplicated rules, as sub-paths to the terminal nodes are shared between the terminal nodes.