🤖 AI Summary
研究了在约束值和梯度存在噪声情况下在线凸优化问题,提出LEDGER方法来控制预算违规,并分析了其预期遗憾与预期预算违规之间的关系。
📝 Abstract
We study constrained online convex optimization with adversarial constraints when constraint values and gradients are observed through unbiased noise. Gaussian value noise of standard deviation $\sigma$ yields a worst-case lower bound of $\Omega(\min\{\sigma,1\}T/\log^7T)$ on the maximum of expected regret and expected hard violation, even with known gradients. This rules out any jointly $O(T^{1-\delta})$ guarantee for fixed $\delta>0$ and fixed positive noise level. We therefore study budget violation: the largest cumulative overspend over any window within a fixed horizon. We introduce \LEDGER, which tracks observed net consumption in a nonnegative balance and sets constraint weights before the current feedback noise. Under common feasibility and conditional finite-variance feedback, for fixed problem parameters, \LEDGER\ achieves $O(\sqrt T/V)$ expected regret and $O(\sqrt V\,T^{3/4}+\sigma\sqrt T)$ expected budget violation for $V\in[T^{-1/2},1]$. This gives the pair $(O(\sqrt T),O(T^{3/4}))$ at $V=1$ and $(O(T^{2/3}),O(T^{2/3}))$ at $V=T^{-1/6}$, without a Slater condition. The budget-focused endpoint $V=T^{-1/2}$ gives $(O(T),O(\sqrt T))$. The same update yields $O((1+E[P_T])\sqrt T/V)$ expected dynamic regret for predictable feasible comparator paths, without common feasibility or path-length input. Its budget bound instead depends on the shortest feasible path, up to a dimension factor.