Multinomial Subset Routing with Sum-Max Rewards and Operational Constraints
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Abstract (arXiv)
We study online routing to subsets of experts under aggregate bandit feedback and long-run operational constraints. Expert contributions can be complementary: for each task dimension, the best selected expert determines the contribution, and the total reward aggregates these dimension-wise maxima. At the same time, capacity, budget, and fairness requirements impose lower and upper bounds on long-run expert activation frequencies. A fixed deterministic subset cannot generally satisfy such heterogeneous requirements, motivating a stochastic routing policy. We formalize this problem as Multinomial Subset Routing (MSR). The learner maintains a distribution (q) over (K) experts, samples an expert independently (M) times from (q), and routes each task to the distinct sampled experts. We propose OMD-Approachability, which combines online mirror descent with Blackwell's approachability to optimize MSR under two-sided operational constraints. We establish (O(T-1/2)) average reward regret and expected constraint violation. We also quantify the approximation gap induced by a linear surrogate, and evaluate the approach on a real-world crowdsourcing dataset.
Key facts. No citing papers in the map yet (data through 7 Oct 2026). Builds on 24 of its 33 references that are in the map. First posted on arXiv 17 Aug 2026.
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References · 24
- 2017Outrageously Large Neural Networks: The Sparsely-Gated Mixture-of-Experts Layercited by 3,413
- 2021Switch Transformers: Scaling to Trillion Parameter Models with Simple and Efficient Sparsitycited by 3,014
- 2019Introduction to Online Convex Optimizationcited by 793
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- 2023Large Language Model Routing with Benchmark Datasetscited by 166
- 2013Bandits with Knapsackscited by 163
- 2024GraphRouter: A Graph-based Router for LLM Selectionscited by 154
- 2024RouterDC: Query-Based Router by Dual Contrastive Learning for Assembling Large Language Modelscited by 84
- 2014Bandits with concave rewards and convex knapsackscited by 83
- 2015Linear Contextual Bandits with Knapsackscited by 82
- 2014Combinatorial Multi-Armed Bandit and Its Extension to Probabilistically Triggered Armscited by 78
- 2018Thompson Sampling for Combinatorial Semi-Banditscited by 78
12 more
- 2018Adversarial Bandits with Knapsackscited by 73
- 2013Thompson Sampling for Complex Bandit Problemscited by 43
- 2015An efficient algorithm for contextual bandits with knapsacks, and an extension to concave objectivescited by 43
- 2024MetaLLM: A High-performant and Cost-efficient Dynamic Framework for Wrapping LLMscited by 39
- 2020FrugalML: How to Use ML Prediction APIs More Accurately and Cheaplycited by 33
- 2022Contextual Bandits with Packing and Covering Constraints: A Modular Lagrangian Approach via Regressioncited by 30
- 2017Combinatorial Semi-Bandits with Knapsackscited by 23
- 2023Combinatorial Stochastic-Greedy Banditcited by 18
- 2020Submodular Bandit Problem Under Multiple Constraintscited by 15
- 2025Learning to Route LLMs from Bandit Feedback: One Policy, Many Trade-offscited by 13
- 2021Efficient Online ML API Selection for Multi-Label Classification Taskscited by 11
- 2023Sum-max Submodular Banditscited by 3
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