Hierarchical Routing Mixture of Experts
This is an incremental improvement for regression tasks with multimodal data, offering a more efficient partitioning approach.
The authors tackled the problem of fitting complex multimodal data distributions in regression by proposing a hierarchical routing mixture of experts model that jointly partitions input-output space, enabling simple leaf experts to make effective predictions, with experiments showing it outperforms other regression models.
In regression tasks the distribution of the data is often too complex to be fitted by a single model. In contrast, partition-based models are developed where data is divided and fitted by local models. These models partition the input space and do not leverage the input-output dependency of multimodal-distributed data, and strong local models are needed to make good predictions. Addressing these problems, we propose a binary tree-structured hierarchical routing mixture of experts (HRME) model that has classifiers as non-leaf node experts and simple regression models as leaf node experts. The classifier nodes jointly soft-partition the input-output space based on the natural separateness of multimodal data. This enables simple leaf experts to be effective for prediction. Further, we develop a probabilistic framework for the HRME model, and propose a recursive Expectation-Maximization (EM) based algorithm to learn both the tree structure and the expert models. Experiments on a collection of regression tasks validate the effectiveness of our method compared to a variety of other regression models.