Stochastic One-Sided Full-Information Bandit
Pith reviewed 2026-05-25 19:36 UTC · model grok-4.3
The pith
An elimination-based algorithm achieves the best-known regret bounds for the stochastic one-sided full-information bandit problem.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The central discovery is that an elimination based algorithm achieves distribution independent regret upper bound O(√(T·log (TK))), and distribution dependent bound O((log T + log K)f(Δ)), and has the best theoretical regret upper bound so far for the stochastic one-sided full-information bandit.
What carries the argument
Elimination-based algorithm that uses one-sided reward observations to generate unbiased estimates for all arms and eliminates suboptimal ones.
If this is right
- The regret bounds apply to the modeling of online repeated second-price auctions.
- Suboptimal arms can be removed efficiently leading to the logarithmic dependence on T and K in the gap-dependent bound.
- The algorithm improves upon prior theoretical guarantees for this bandit variant.
- Empirical tests confirm better performance compared to alternative approaches.
Where Pith is reading between the lines
- The technique of using one-sided feedback for unbiased estimates could apply to other auction or ranking-based decision problems.
- Analyzing the specific form of f(Δ) might reveal how the bound behaves under particular gap structures.
- The bounds suggest potential for low-regret reserve price selection in repeated auctions with many bidders.
Load-bearing premise
The one-sided observations from playing arm i suffice to produce unbiased estimates of all relevant arm means, allowing the elimination procedure to remove suboptimal arms at the rate needed for the stated regret bounds to hold.
What would settle it
A simulation or theoretical construction where the algorithm's regret grows faster than O(sqrt(T log(TK))) as T increases, under arbitrary reward distributions, would falsify the distribution-independent bound.
Figures
read the original abstract
In this paper, we study the stochastic version of the one-sided full information bandit problem, where we have $K$ arms $[K] = \{1, 2, \ldots, K\}$, and playing arm $i$ would gain reward from an unknown distribution for arm $i$ while obtaining reward feedback for all arms $j \ge i$. One-sided full information bandit can model the online repeated second-price auctions, where the auctioneer could select the reserved price in each round and the bidders only reveal their bids when their bids are higher than the reserved price. In this paper, we present an elimination-based algorithm to solve the problem. Our elimination based algorithm achieves distribution independent regret upper bound $O(\sqrt{T\cdot\log (TK)})$, and distribution dependent bound $O((\log T + \log K)f(\Delta))$, where $T$ is the time horizon, $\Delta$ is a vector of gaps between the mean reward of arms and the mean reward of the best arm, and $f(\Delta)$ is a formula depending on the gap vector that we will specify in detail. Our algorithm has the best theoretical regret upper bound so far. We also validate our algorithm empirically against other possible alternatives.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper studies the stochastic one-sided full-information bandit problem with K arms, where playing arm i yields a reward sample from arm i's unknown distribution together with reward observations for all arms j ≥ i. It proposes an elimination-based algorithm and claims it attains a distribution-independent regret bound of O(√(T log(TK))) and a distribution-dependent bound of O((log T + log K) f(Δ)), where f(Δ) is a gap-dependent function specified in the paper; the algorithm is asserted to have the best known theoretical regret upper bound and is supported by empirical comparisons.
Significance. If the stated regret bounds hold under the one-sided feedback model, the work supplies improved theoretical guarantees for a structured bandit setting that directly models repeated second-price auctions. The elimination procedure and the explicit rates constitute a technical contribution that extends classical stochastic bandit analysis to partial-observation regimes, with potential implications for online mechanism design.
minor comments (3)
- [Abstract] Abstract: the function f(Δ) is referenced but not defined or sketched; a one-sentence description or pointer to the precise expression (presumably in §4 or §5) would improve readability.
- [Experiments] The empirical section should report the precise number of independent runs, the range of T and K tested, and the exact baselines (including any prior one-sided algorithms) to allow direct replication of the claimed superiority.
- [Preliminaries] Notation: the definition of the gap vector Δ and the precise form of the elimination threshold should be stated once in a dedicated preliminary section rather than introduced inline in the algorithm description.
Simulated Author's Rebuttal
We thank the referee for the positive assessment of our work, the recognition of its significance for structured bandit problems and online mechanism design, and the recommendation of minor revision. No specific major comments were raised in the report.
Circularity Check
No circularity: derivation relies on standard concentration and elimination
full rationale
The paper presents an elimination algorithm for the one-sided full-information bandit and derives distribution-independent regret O(√(T log(TK))) and distribution-dependent O((log T + log K) f(Δ)) bounds. These follow from unbiased estimates obtained directly from one-sided observations and standard concentration inequalities applied to empirical means; elimination thresholds are set accordingly. No step reduces a claimed prediction to a fitted parameter by construction, no self-citation is load-bearing for the central bounds, and the modeling assumptions (unbiasedness from one-sided feedback) are external to the regret derivation itself. The result is therefore self-contained against external benchmarks.
Axiom & Free-Parameter Ledger
Reference graph
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[13]
+ Pr{j /∈St}µ∗) =µ∗ − 1 K K∑ j=1 I{j ∈St}ε 8 ≤µ∗ − ε 24. Then choose ε = √ c lnK/T , and sum over t which satisfies c lnK 2ε2 ≤ t ≤ c lnK ε2 , we complete the proof. ⊓ ⊔
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