Online Resource Allocation with Replenishable Budgets

Online Resource Allocation (ORA) is a fundamental framework for sequential decision-making problems under budget constraints. Classical ORA models typically assume that resources are monotonic, meaning that selecting actions can only decrease the available budget. In this work, we study a more general setting with replenishable budgets, in which actions may either consume or replenish resources over time. This extension is necessary to capture scenarios such as inventory systems or energy markets in which capacity can be actively recovered. We develop a dual-based algorithm that recovers best-of-both-world guarantees for standard ORA when the replenishment factor $\beta =0$, and improves them when $\beta >0$. In particular, our algorithm attains $\tilde{\mathcal{O}}(\sqrt{T})$ regret in the stochastic setting and $\tilde{\mathcal{O}}(\sqrt{T})$ $\alpha$-regret in the adversarial setting, where $\alpha$ depends on the per-round budget and on the replenishment factor of the void action. Moreover, the algorithm ensures strict satisfaction of the budget constraints.