Develops first optimal algorithm for logistic bandits.
problem Pure exploration in logistic bandits.
method Logistic track-and-stop (Log-TS) algorithm.
result Asymptotically matches lower bound for expected sample complexity.
Improved regret bounds for logistic bandits via novel confidence set construction.
problem Dependencies in parameter space for logistic bandits, especially when S ≥ d S \geq d S ≥ d . method Regret-to-confidence-set conversion (R2CS) to construct convex confidence sets.
result Strict improvement in regret bound w.r.t. S S S in logistic bandits. New algorithm reduces regret for logistic bandits without κ κ κ dependency.
problem Logistic bandits have poor frequentist regret guarantees due to large κ κ κ . method Optimistic algorithm based on self-normalized martingale tail-inequality.
result Achieves i l d e O ( T ) ilde{\mathcal{O}}(\sqrt{T}) i l d e O ( T ) regret with no κ κ κ dependency. This work improves regret minimization for logistic bandits by reducing dependence on a large constant.
problem Minimizing regret in logistic bandits with reduced dependence on a large constant.
method Experimental design procedure and warmup sampling algorithm.
result Achieves a minimax regret of \(O(\sqrt{d \dotμT\log(|\mathcal{X}|)})\) in the fixed arm setting.
Improved confidence bounds for linear logistic model with applications to bandits.
problem Improving confidence bounds for linear logistic model.
method Self-concordant analysis of the logistic loss to avoid dependence on worst-case variance.
result Significant improvement in confidence bounds, avoiding dependence on 1 / κ 1/κ 1/ κ . We address the problem of regret minimization in logistic contextual bandits, where a learner decides among sequential actions or arms given their respective contexts to maximize binary rewards. Using a fast inference procedure with Polya-Gamma distributed augmentation variables, we propose an improved version of Thomp…
New algorithms reduce regret in neural logistic bandits.
problem Learning unknown reward functions in neural networks.
method Introduced a Bernstein-type inequality for self-normalized vector-valued martingales.
result Regret bounds improved to O ~ ( d ~ κ T ) \widetilde{O}(\widetilde{d}\sqrt{κT}) O ( d κ T ) and O ~ ( d ~ T / κ ) \widetilde{O}(\widetilde{d}\sqrt{T/κ}) O ( d T / κ ) . Improved algorithm for logistic bandits with better regret bounds.
problem Understanding the impact of non-linearity in logistic bandits.
method Introducing a new algorithm and providing refined analysis.
result Improved regret bounds scaling as O ~ ( d T / κ ) \tilde{\mathcal{O}}(d\sqrt{T/κ}) O ~ ( d T / κ ) in most favorable cases. Improved Thompson Sampling for logistic bandits with information-theoretic analysis.
problem Optimizing binary reward probabilities in logistic bandit problems.
method Information-theoretic framework, focusing on the information ratio and minimax measure.
result Bound on Bayesian expected regret of O ( d / α T log ( β T / d ) ) O(d/α\sqrt{T \log(βT/d)}) O ( d / α T log ( β T / d ) ) for logistic bandits. Improved regret bound for multinomial logistic bandits with non-linearity.
problem Maximizing rewards in multinomial logistic bandits with non-linear feedback.
method Extended the definition of κ ∗ κ_* κ ∗ to multinomial setting and proposed an efficient algorithm. result Minimax-optimal regret bound of O ~ ( R d K T / κ ∗ ) \smash{\widetilde{\mathcal{O}}( R d \sqrt{ {KT}/{κ_*}} ) } O ( R d K T / κ ∗ ) , improving over existing guarantees. Two algorithms achieve optimal regret with limited adaptivity in multinomial logistic bandits.
problem Achieving optimal regret with limited adaptivity in multinomial logistic bandits.
method Presented two algorithms, B-MNL-CB and RS-MNL, for batched and rarely-switching paradigms.
result Achieved i l d e O ( T ) ilde{O}(\sqrt{T}) i l d e O ( T ) regret with limited adaptivity. New algorithm for maximizing revenue in multinomial logistic bandits.
problem Maximizing revenue in scenarios with multiple outcomes.
method MNL-UCB algorithm based on upper confidence bounds.
result Achieves regret i l d e O ( d K T ) ilde{\mathcal{O}}(dK\sqrt{T}) i l d e O ( d K T ) with small dependency on constants. A new algorithm reduces the time and space complexity for multinomial logistic bandits.
problem High-dimensional feedback in multinomial logistic bandits makes existing algorithms inefficient.
method Integrates frequent directions matrix sketching into OFUL-MLogB to reduce time and space complexity.
result Achieves a regret bound of i l d e O ( Δ T ( K d ln Δ T + m ) T ) ilde{\mathcal{O}}(Δ_T(Kd\lnΔ_T+m)\sqrt{T}) i l d e O ( Δ T ( K d ln Δ T + m ) T ) . Improved online confidence bounds for multinomial logistic models in bandits.
problem Achieving optimal regret in multinomial logistic bandits with bounded parameters and outcomes.
method Deriving an improved online confidence bound and proposing OFU-MNL++ and OFU-MN 2 ^2 2 L algorithms. result Achieved variance-dependent optimal regret for MNL bandits.
We study the logistic bandit, in which rewards are binary with success probability exp ( β a ⊤ θ ) / ( 1 + exp ( β a ⊤ θ ) ) \exp(βa^\top θ) / (1 + \exp(βa^\top θ)) exp ( β a ⊤ θ ) / ( 1 + exp ( β a ⊤ θ )) and actions a a a and coefficients θ θ θ are within the d d d -dimensional unit ball. While prior regret bounds for algorithms that address the logistic bandit exhibit exponential dependence on the slop…
Improved regret bound for MNL MDPs with variance-aware approach.
problem Optimal reinforcement learning for MNL MDPs with structured variance.
method Introducing a problem-dependent constant measuring average variance, proposing an algorithm with improved regret bound.
result Minimax optimal regret bound of O ( d H 2 σ ˉ T T ) O(dH^2\barσ_T\sqrt{T}) O ( d H 2 σ ˉ T T ) for structured MDPs. FOLKLORE algorithm speeds up online multiclass logistic regression.
problem Efficiently solving online multiclass logistic regression without high computational cost.
method Developed FOLKLORE algorithm with improved runtime and regret bound.
result First practical algorithm for online multiclass logistic regression.
This work explores adaptations of successful multi-armed bandits policies to the online contextual bandits scenario with binary rewards using binary classification algorithms such as logistic regression as black-box oracles. Some of these adaptations are achieved through bootstrapping or approximate bootstrapping, whil…
Unified CS for GLMs improves bandit regret bounds.
problem Improving regret bounds for GLMs in bandit settings.
method Unified likelihood ratio-based CS with PAC-Bayesian bound.
result Unified CS attains poly(S)-free regret for Bernoulli.
We study two randomized algorithms for generalized linear bandits. The first, GLM-TSL, samples a generalized linear model (GLM) from the Laplace approximation to the posterior distribution. The second, GLM-FPL, fits a GLM to a randomly perturbed history of past rewards. We analyze both algorithms and derive $\tilde{O}(…
This paper tackles open problem of tight bounds for KBs with Bernoulli rewards.
problem Open problem of tight bounds for Kernelized Bandits with Bernoulli rewards.
method Focus on Bernoulli model, not subgaussian noise, and optimize function in RKHS.
result Open problem remains unsolved in this context.
Contextual bandits are widely used in Internet services from news recommendation to advertising, and to Web search. Generalized linear models (logistical regression in particular) have demonstrated stronger performance than linear models in many applications where rewards are binary. However, most theoretical analyses …
We propose a new online algorithm for cumulative regret minimization in a stochastic linear bandit. The algorithm pulls the arm with the highest estimated reward in a linear model trained on its perturbed history. Therefore, we call it perturbed-history exploration in a linear bandit (LinPHE). The perturbed history is …
A new thompson sampling method controls for time-varying effects.
problem Dynamic experiments in online services with time-varying effects.
method Odds-ratio Thompson Sampling
result The proposed method works robust to time-varying effects.
Information-theoretic Bayesian regret bounds of Russo and Van Roy capture the dependence of regret on prior uncertainty. However, this dependence is through entropy, which can become arbitrarily large as the number of actions increases. We establish new bounds that depend instead on a notion of rate-distortion. Among o…
New algorithm reduces regret in bandit optimization for high-dimensional data.
problem Optimizing decisions in uncertain environments with high-dimensional data.
method Inspired by online Newton step, proposes a simple and efficient BCO algorithm.
result Achieves optimal regret bounds for κ κ κ -convex functions. New GLB algorithm handles non-stationary data with forgetting.
problem Non-stationary GLB with non-convex projection or burn-in phases.
method Self-concordant GLB with sliding window or exponential weights for forgetting.
result Novel confidence-based algorithm for maximum likelihood estimator.
Learning linear predictors with the logistic loss---both in stochastic and online settings---is a fundamental task in machine learning and statistics, with direct connections to classification and boosting. Existing "fast rates" for this setting exhibit exponential dependence on the predictor norm, and Hazan et al. (20…
The paper achieves nearly optimal regret bounds for contextual multinomial logit bandits.
problem The contextual multinomial logit (MNL) bandit problem with varying rewards.
method Established lower bounds and proposed OFU-MNL+ algorithm with matching upper bounds.
result Achieved minimax optimal regret bounds for both uniform and non-uniform reward settings.
Gaptron algorithm reduces mistakes in online multiclass classification.
problem Online multiclass classification with limited information.
method Randomized first-order algorithm exploiting the gap between zero-one loss and surrogate losses.
result First linear time algorithm with O ( K T ) O(K\sqrt{T}) O ( K T ) expected regret. A new algorithm reduces regret in bandit problems with adversarial corruptions.
problem Optimizing decision-making in bandit problems with variable uncertainties and adversarial interference.
method Proposes HCW-GLB-OMD, an OMD-based estimator with Hessian-based confidence weights for robustness.
result Achieves instance-wise minimax optimality with a κ κ κ -factor in the corruption term. RAVEN-UCB addresses non-stationary MAB problems with tighter regret bounds.
problem Non-stationary environments in multi-armed bandits.
method Combines variance-aware adaptation with three innovations: confidence bounds, adaptive control, and recursive updates.
result Achieves tighter regret bounds than UCB1 and UCB-V.
MAXMINLCB optimizes unknown target functions with preference feedback using a Stackelberg game approach.
problem Optimizing unknown target functions with pairwise comparisons and human feedback.
method MAXMINLCB, a zero-sum Stackelberg game, balances exploration and exploitation.
result MAXMINLCB consistently outperforms existing algorithms with a rate-optimal regret guarantee.
New algorithms for GLMs adapt to non-stationary contexts.
problem Dealing with abrupt changes in non-stationary environments.
method Upper Confidence Bound algorithms using sliding window or discounted maximum-likelihood.
result Theoretical guarantees on dynamic regret of order d^2/3 G^1/3 T^2/3.
FAB-COST improves cold-start recommendation accuracy with less data.
problem Cold-start problem in recommendation systems.
method Contextual bandit algorithm using Expectation Propagation and Assumed Density Filtering.
result FAB-COST outperforms Laplace approximation on real data.
Paper tackles combinatorial reinforcement learning with preference feedback.
problem Modeling long-term user engagement in scenarios like recommender systems and online advertising.
method Assumes a contextual MNL preference model with linear mean utilities and approximates item values. Proposes MNL-VQL algorithm.
result Achieves nearly minimax-optimal regret for linear MDPs with preference feedback.
Maximum likelihood estimator performance in logistic regression analyzed.
problem Performance of maximum likelihood estimator in logistic regression.
method Sharp non-asymptotic guarantees for existence and excess logistic risk.
result Sharp guarantees for the existence and excess risk of MLE in logistic regression.
Paper finds a lower bound for estimating low-rank matrices in logistic regression.
problem Estimating low-rank coefficient matrices in logistic regression.
method Derives a minimax lower bound on the risk.
result The bound depends on matrix dimensions, rank, and sample size.
Revises logistic-softmax likelihood for Bayesian meta-learning in few-shot classification.
problem Inherent uncertainty in logistic-softmax leads to suboptimal performance in meta-learning.
method Redesigns logistic-softmax likelihood with a temperature parameter for better control of prior confidence.
result Achieves well-calibrated uncertainty estimates and comparable/superior performance on benchmark datasets.
Novel bounds for logistic regression coreset construction and feature selection.
problem Efficiently summarize and reduce logistic regression inputs.
method Feature space sketching for logistic regression.
result Tight bounds for coreset construction and feature selection.
Unified framework for sparse logistic regression with nonconvex regularization.
problem Sparse logistic regression with nonconvex regularization.
method Unified framework, line search criteria for nonconvex terms.
result Effective classification and feature selection at lower computational cost.
Study explores geometric structure and prior for beta-logistic distribution.
problem Understanding the geometric structure and prior distributions of the beta-logistic distribution.
method Exploring dual geometric structure and uncovering α \alpha α -parallel prior. result The beta-logistic distribution admits an α \alpha α -parallel prior for any real number α \alpha α . We comment on the fact that gradient ascent for logistic regression has a connection with the perceptron learning algorithm. Logistic learning is the "soft" variant of perceptron learning.
Paper explains learning property of logistic and softmax losses for balanced and imbalanced class data.
problem Understanding and optimizing loss functions for deep neural networks with class imbalances.
method Analyzing necessary conditions for convergence of logistic and softmax losses in CNNs.
result Proposes a novel reweighted logistic loss function that improves performance over softmax loss.
Improved sketching for logistic and ℓ 1 \ell_1 ℓ 1 regression with near-linear dimensions.
problem Efficiently approximate ℓ 1 \ell_1 ℓ 1 and logistic regression problems. method New sketching techniques achieving near-linear dimensions for both problems.
result Achieved near-linear sketching dimensions for ℓ 1 \ell_1 ℓ 1 and logistic regression. Safe screening rules reduce computation time in logistic regression with ℓ 0 − ℓ 2 \ell_0-\ell_2 ℓ 0 − ℓ 2 regularization.
problem Efficiently solving logistic regression with many features and regularization.
method Screening rules based on Fenchel dual lower bounds of strong conic relaxations.
result A high percentage of features can be safely removed before solving, leading to substantial speed-up.
Proposes logistic-beta process for modeling dependent probabilities with beta marginals.
problem Limited work on flexible and computationally convenient stochastic process extensions for dependent random probabilities.
method Introduces logistic-beta process with logistic transformation and beta marginals, capable of modeling dependence in discrete and continuous domains.
result Logistic-beta processes enable effective posterior inference and design of computationally tractable dependent Bayesian nonparametric models.
Classification is the most important process in data analysis. However, due to the inherent non-convex and non-smooth structure of the zero-one loss function of the classification model, various convex surrogate loss functions such as hinge loss, squared hinge loss, logistic loss, and exponential loss are introduced. T…