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An Enhanced Projection Pursuit Tree Classifier with Visual Methods for Assessing Algorithmic Improvements

da Silva, Natalia, Cook, Dianne, Lee, Eun-Kyung

arXiv.org Machine Learning

This paper presents enhancements to the projection pursuit tree classifier and visual diagnostic methods for assessing their impact in high dimensions. The original algorithm uses linear combinations of variables in a tree structure where depth is constrained to be less than the number of classes -- a limitation that proves too rigid for complex classification problems. Our extensions improve performance in multi-class settings with unequal variance-covariance structures and nonlinear class separations by allowing more splits and more flexible class groupings in the projection pursuit computation. Proposing algorithmic improvements is straightforward; demonstrating their actual utility is not. We therefore develop two visual diagnostic approaches to verify that the enhancements perform as intended. Using high-dimensional visualization techniques, we examine model fits on benchmark datasets to assess whether the algorithm behaves as theorized. An interactive web application enables users to explore the behavior of both the original and enhanced classifiers under controlled scenarios. The enhancements are implemented in the R package PPtreeExt.



Arbitrarily Scalable Environment Generators via Neural Cellular Automata

Neural Information Processing Systems

We study the problem of generating arbitrarily large environments to improve the throughput of multi-robot systems. Prior work proposes Quality Diversity (QD) algorithms as an effective method for optimizing the environments of automated warehouses. However, these approaches optimize only relatively small environments, falling short when it comes to replicating real-world warehouse sizes. The challenge arises from the exponential increase in the search space as the environment size increases.







f649556471416b35e60ae0de7c1e3619-Paper-Conference.pdf

Neural Information Processing Systems

As a motivating example, consider deploying a robot agent at scale in a varietyofhomeenvironments. Therobotshouldgeneralize byperforming robustlynotonlyintest homes, butinanyenduser'shome.


ReCo: RetrieveandCo-segment forZero-shotTransfer

Neural Information Processing Systems

There isarichbody ofsemantic segmentation literature thatproposes solutions tosubsets ofthese challenges, but to our knowledge no existing work addresses their full combination.