Title
Comparison of the Representational Power of Random Forests, Binary Decision Diagrams, and Neural Networks
Abstract
In this letter, we compare the representational power of random forests, binary decision diagrams (BDDs), and neural networks in terms of the number of nodes. We assume that an axis-aligned function on a single variable is assigned to each edge in random forests and BDDs, and the activation functions of neural networks are sigmoid, rectified linear unit, or similar functions. Based on existing studies, we show that for any random forest, there exists an equivalent depth-3 neural network with a linear number of nodes. We also show that for any BDD with balanced width, there exists an equivalent shallow depth neural network with a polynomial number of nodes. These results suggest that even shallow neural networks have the same or higher representation power than deep random forests and deep BDDs. We also show that in some cases, an exponential number of nodes are required to express a given random forest by a random forest with a much fewer number of trees, which suggests that many trees are required for random forests to represent some specific knowledge efficiently.
Year
DOI
Venue
2022
10.1162/neco_a_01486
Neural Computation
DocType
Volume
Issue
Journal
34
4
ISSN
Citations 
PageRank 
0899-7667
0
0.34
References 
Authors
0
2
Name
Order
Citations
PageRank
So Kumano100.34
Tatsuya Akutsu232.07