提出新算法,高效降低复杂博弈中的交换后悔,适用于在线预测校准。
Full Swap Regret and Discretized Calibration
- 设计基于嵌入空间的高效学习算法,处理大规模动作集。
- 实现 $\tilde{O}(T^{(d+1)/(d+3)})$ 交换后悔,优于传统方法。
- 可直接用于在线预测,保证 $O(T^{1/3})$ 校准误差,适合高精度场景。
我们研究结构化正则形式博弈中最小化交换后悔的问题。玩家有极大(可能无限)数量的纯策略,但每个策略可嵌入 $d$ 维空间,收益由这些嵌入的双线性函数给出。本文提出一种高效学习算法,经过 $T$ 轮后交换后悔不超过 $\tilde{O}(T^{(d+1)/(d+3)})$。为此,引入新的在线学习问题——全交换后悔最小化:学习者在有界凸 $d$ 维动作集 $\mathcal{K}$ 中反复选择随机动作,随后接收对手的损失,目标是最小化相对于最坏情况交换函数 $\mathcal{K} \to \mathcal{K}$ 的后悔。针对损失函数的凸性与光滑性不同假设,设计出后悔界从 $O(T^{d/(d+2)})$ 到 $O(T^{(d+1)/(d+2)})$ 的算法。最后,将这些工具应用于在线预测以最小化校准误差,证明多种校准概念是全交换后悔的特例。特别地,设计了高效在线预测算法,保证 $\ell_2$-校准误差不超过 $O(T^{1/3})$,且在预测值为 $\varepsilon$ 倍数时,离散校准误差不超过 $O(\max(\sqrt{\varepsilon T}, T^{1/3}))$。
原文摘要 · Abstract (English)
We study the problem of minimizing swap regret in structured normal-form games. Players have a very large (potentially infinite) number of pure actions, but each action has an embedding into $d$-dimensional space and payoffs are given by bilinear functions of these embeddings. We provide an efficient learning algorithm for this setting that incurs at most $\tilde{O}(T^{(d+1)/(d+3)})$ swap regret after $T$ rounds. To achieve this, we introduce a new online learning problem we call \emph{full swap regret minimization}. In this problem, a learner repeatedly takes a (randomized) action in a bounded convex $d$-dimensional action set $\mathcal{K}$ and then receives a loss from the adversary, with the goal of minimizing their regret with respect to the \emph{worst-case} swap function mapping $\mathcal{K}$ to $\mathcal{K}$. For varied assumptions about the convexity and smoothness of the loss functions, we design algorithms with full swap regret bounds ranging from $O(T^{d/(d+2)})$ to $O(T^{(d+1)/(d+2)})$. Finally, we apply these tools to the problem of online forecasting to minimize calibration error, showing that several notions of calibration can be viewed as specific instances of full swap regret. In particular, we design efficient algorithms for online forecasting that guarantee at most $O(T^{1/3})$ $\ell_2$-calibration error and $O(\max(\sqrt{εT}, T^{1/3}))$ \emph{discretized-calibration} error (when the forecaster is restricted to predicting multiples of $ε$).
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