A Regression Tsetlin Machine with Integer Weighted Clauses for Compact Pattern Representation

TL;DR

This paper introduces an integer weighted extension to the Regression Tsetlin Machine, significantly reducing computational costs and improving interpretability while maintaining or enhancing accuracy in nonlinear regression tasks.

Contribution

It proposes a novel integer weighted clause representation and a learning scheme to efficiently capture patterns and optimize weights, advancing interpretability and computational efficiency in RTMs.

Findings

Integer weighted RTMs achieve comparable or better accuracy than regular RTMs.

The integer weighting reduces computational cost proportionally to the weight value.

Integer weights improve accuracy over real-valued weights.

Abstract

The Regression Tsetlin Machine (RTM) addresses the lack of interpretability impeding state-of-the-art nonlinear regression models. It does this by using conjunctive clauses in propositional logic to capture the underlying non-linear frequent patterns in the data. These, in turn, are combined into a continuous output through summation, akin to a linear regression function, however, with non-linear components and unity weights. Although the RTM has solved non-linear regression problems with competitive accuracy, the resolution of the output is proportional to the number of clauses employed. This means that computation cost increases with resolution. To reduce this problem, we here introduce integer weighted RTM clauses. Our integer weighted clause is a compact representation of multiple clauses that capture the same sub-pattern-N repeating clauses are turned into one, with an integer weight N. This reduces computation cost N times, and increases interpretability through a sparser representation. We further introduce a novel learning scheme that allows us to simultaneously learn both the clauses and their weights, taking advantage of so-called stochastic searching on the line. We evaluate the potential of the integer weighted RTM empirically using six artificial datasets. The results show that the integer weighted RTM is able to acquire on par or better accuracy using significantly less computational resources compared to regular RTMs. We further show that integer weights yield improved accuracy over real-valued ones.