Is Online Linear Optimization Sufficient for Strategic Robustness?
2026-02-12 • Computer Science and Game Theory
Computer Science and Game TheoryMachine Learning
AI summaryⓘ
The authors study how to bid effectively in repeated first-price auctions where bidders have incomplete information. They focus on algorithms that not only minimize regret (meaning they perform nearly as well as the best fixed bid in hindsight) but are also robust against manipulations by the seller. They show that using simple online linear optimization methods, one can design bidding strategies that maintain strategic robustness while improving computational and statistical efficiency compared to previous approaches. Their methods work both when the bidder knows the distribution of values and when they do not, even removing some prior technical assumptions.
Bayesian first-price auctionsregret minimizationstrategic robustnessno-regret algorithmsonline gradient ascentonline linear optimizationno-swap-regretvalue distributioncomputational efficiencystatistical efficiency
Authors
Yang Cai, Haipeng Luo, Chen-Yu Wei, Weiqiang Zheng
Abstract
We consider bidding in repeated Bayesian first-price auctions. Bidding algorithms that achieve optimal regret have been extensively studied, but their strategic robustness to the seller's manipulation remains relatively underexplored. Bidding algorithms based on no-swap-regret algorithms achieve both desirable properties, but are suboptimal in terms of statistical and computational efficiency. In contrast, online gradient ascent is the only algorithm that achieves $O(\sqrt{TK})$ regret and strategic robustness [KSS24], where $T$ denotes the number of auctions and $K$ the number of bids. In this paper, we explore whether simple online linear optimization (OLO) algorithms suffice for bidding algorithms with both desirable properties. Our main result shows that sublinear linearized regret is sufficient for strategic robustness. Specifically, we construct simple black-box reductions that convert any OLO algorithm into a strategically robust no-regret bidding algorithm, in both known and unknown value distribution settings. For the known value distribution case, our reduction yields a bidding algorithm that achieves $O(\sqrt{T \log K})$ regret and strategic robustness (with exponential improvement on the $K$-dependence compared to [KSS24]). For the unknown value distribution case, our reduction gives a bidding algorithm with high-probability $O(\sqrt{T (\log K+\log(T/δ)})$ regret and strategic robustness, while removing the bounded density assumption made in [KSS24].