Benjamin Heymann

On the Role of Tie-Breaking Rules in the Convergence of Fictitious Play for Symmetric First-Price Auctions

Benjamin Heymann

We study continuous-time fictitious play in 2-bidder, symmetric first-price auctions with independently distributed discrete values and a discrete bid set. We first exhibit a minimal instance --- two bidders, two values, three positive bids --- on which fictitious play with the standard …

jp, fr (code pays fourni par la source)

An Asymptotic Analysis of the Shapley Value for Dataset Valuation

Mélissa Tamine, Benjamin Heymann, Maxime Vono, Patrick Loiseau

We propose an asymptotic analysis of the Shapley value in a dataset valuation setting in which utilities are modeled as smooth functionals of empirical distributions via reproducing kernel Hilbert space (RKHS) mean embeddings. We prove that, despite its combinatorial definition, the Shapley …

An Asymptotic Analysis of the Shapley Value for Dataset Valuation

Mélissa Tamine, Benjamin Heymann, Maxime Vono, Patrick Loiseau

We propose an asymptotic analysis of the Shapley value in a dataset valuation setting in which utilities are modeled as smooth functionals of empirical distributions via reproducing kernel Hilbert space (RKHS) mean embeddings. We prove that, despite its combinatorial definition, the Shapley …

fr (code pays fourni par la source)

An empirical study of Fictitious Play for estimating Nash equilibria in first-price auctions with correlated values

Benjamin Heymann, Panayotis Mertikopoulos

This study concerns the computation of the Nash equilibria of first-price auctions with correlated values. Although some equilibrium computation methods exist for auctions with independent values, the correlation of bidders' values introduces significant complications that render the existing methods unsatisfactory. Our empirical …

jp, fr, af (code pays fourni par la source)

An empirical study of Fictitious Play for estimating Nash equilibria in first-price auctions with correlated values

Benjamin Heymann, Panayotis Mertikopoulos

This study concerns the computation of the Nash equilibria of first-price auctions with correlated values. Although some equilibrium computation methods exist for auctions with independent values, the correlation of bidders' values introduces significant complications that render the existing methods unsatisfactory. Our empirical …

fr (code pays fourni par la source)

Learning to Bid in Repeated Second-Price Auctions with Dynamic Values and Aggregated Feedback

Benjamin Heymann, Otmane Sakhi

We study the problem of learning to bid when the bidder's value is dynamic, i.e., when the current value depends on past outcomes. Specifically, we consider a bidder participating in repeated second-price auctions whose value depends on the time elapsed since their …

Learning to Bid in Repeated Second-Price Auctions with Dynamic Values and Aggregated Feedback

Benjamin Heymann, Otmane Sakhi

We study the problem of learning to bid when the bidder's value is dynamic, i.e., when the current value depends on past outcomes. Specifically, we consider a bidder participating in repeated second-price auctions whose value depends on the time elapsed since their …

jp, fr (code pays fourni par la source)

RecoAtlas: From Semantic Plausibility to Set-Level Utility in LLM Recommendation Agents

Imad Aouali, Flavian Vasile, Otmane Sakhi, Alexandre Gilotte et autres

LLM recommendation agents increasingly produce structured recommendation reports: sets of items accompanied by natural-language justifications. Yet existing evaluations often reduce this setting to reranking small shortlisted candidate sets or judge reports mainly by semantic plausibility. We introduce Recommendation Atlas (Agentic Tool-Level Assessment …

RecoAtlas: From Semantic Plausibility to Set-Level Utility in LLM Recommendation Agents

Imad Aouali, Flavian Vasile, Otmane Sakhi, Alexandre Gilotte et autres

LLM recommendation agents increasingly produce structured recommendation reports: sets of items accompanied by natural-language justifications. Yet existing evaluations often reduce this setting to reranking small shortlisted candidate sets or judge reports mainly by semantic plausibility. We introduce Recommendation Atlas (Agentic Tool-Level Assessment …

Side-by-side first-price auctions with imperfect bidders

Benjamin Heymann

We model a procurement scenario in which two \textit{imperfect} bidders act simultaneously on behalf of a single buyer, a configuration common in display advertising and referred to as \textit{side-by-side bidding} but largely unexplored in theory. We prove that the iterated best response …

Counterfactual simulations for large scale systems with burnout variables

Benjamin Heymann

International audience

fr (code pays fourni par la source)

Offline Contextual Bandit with Counterfactual Sample Identification

Alexandre Gilotte, Otmane Sakhi, Imad Aouali, Benjamin Heymann

In production systems, contextual bandit approaches often rely on direct reward models that take both action and context as input. However, these models can suffer from confounding, making it difficult to isolate the effect of the action from that of the context. …