Exploring Large Action Sets with Hyperspherical Embeddings using von Mises-Fisher Sampling

Fuente: arXiv
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Main Authors: Bendada, Walid, Salha-Galvan, Guillaume, Hennequin, Romain, Bontempelli, Théo, Bouabça, Thomas, Cazenave, Tristan
Format: Preprint
Published: 2025
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author Bendada, Walid
Salha-Galvan, Guillaume
Hennequin, Romain
Bontempelli, Théo
Bouabça, Thomas
Cazenave, Tristan
author_facet Bendada, Walid
Salha-Galvan, Guillaume
Hennequin, Romain
Bontempelli, Théo
Bouabça, Thomas
Cazenave, Tristan
contents This paper introduces von Mises-Fisher exploration (vMF-exp), a scalable method for exploring large action sets in reinforcement learning problems where hyperspherical embedding vectors represent these actions. vMF-exp involves initially sampling a state embedding representation using a von Mises-Fisher distribution, then exploring this representation's nearest neighbors, which scales to virtually unlimited numbers of candidate actions. We show that, under theoretical assumptions, vMF-exp asymptotically maintains the same probability of exploring each action as Boltzmann Exploration (B-exp), a popular alternative that, nonetheless, suffers from scalability issues as it requires computing softmax values for each action. Consequently, vMF-exp serves as a scalable alternative to B-exp for exploring large action sets with hyperspherical embeddings. Experiments on simulated data, real-world public data, and the successful large-scale deployment of vMF-exp on the recommender system of a global music streaming service empirically validate the key properties of the proposed method.
format Preprint
id arxiv_https___arxiv_org_abs_2507_00518
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Exploring Large Action Sets with Hyperspherical Embeddings using von Mises-Fisher Sampling
Bendada, Walid
Salha-Galvan, Guillaume
Hennequin, Romain
Bontempelli, Théo
Bouabça, Thomas
Cazenave, Tristan
Machine Learning
Information Retrieval
This paper introduces von Mises-Fisher exploration (vMF-exp), a scalable method for exploring large action sets in reinforcement learning problems where hyperspherical embedding vectors represent these actions. vMF-exp involves initially sampling a state embedding representation using a von Mises-Fisher distribution, then exploring this representation's nearest neighbors, which scales to virtually unlimited numbers of candidate actions. We show that, under theoretical assumptions, vMF-exp asymptotically maintains the same probability of exploring each action as Boltzmann Exploration (B-exp), a popular alternative that, nonetheless, suffers from scalability issues as it requires computing softmax values for each action. Consequently, vMF-exp serves as a scalable alternative to B-exp for exploring large action sets with hyperspherical embeddings. Experiments on simulated data, real-world public data, and the successful large-scale deployment of vMF-exp on the recommender system of a global music streaming service empirically validate the key properties of the proposed method.
title Exploring Large Action Sets with Hyperspherical Embeddings using von Mises-Fisher Sampling
topic Machine Learning
Information Retrieval
url https://arxiv.org/abs/2507.00518