arXiv subjects

Yukihiko Funaki

Publications and source records attributed to Yukihiko Funaki.

6 recordsLinked to original sources

arXiv2026

Sequential Pricing Mechanisms for Surplus Division

Extending the Price-and-Choose (P&C) mechanism of Echenique and Nunez (2025), we propose the Price-Accept-and-Choose (PA&C) mechanism, which preserves efficiency while eliminating P&C's first-mover advantage. We then analyze randomized and bidding variants and show that the resulting equilibrium payoffs correspond to standard solutions in transferable utility games: the Center of the Imputation Set value for P&C and the Shapley value for PA&C. In the randomized variants, these solutions arise in expectation; in the bidding variants, they are implemented on every equilibrium path. We further relate other efficient designs, such as balanced VCG payments, to additional solution concepts, forging an interpretable bridge between implementation theory and cooperative game theory.

econ.TH↗

arXiv2025

Characterizing the ELS Values with Fixed-Population Invariance Axioms

We study efficient, linear, and symmetric (ELS) values, a central family of allocation rules for cooperative games with transferable-utility (TU-games) that includes the Shapley value, the CIS value, and the ENSC value. We first show that every ELS value can be written as the Shapley value of a suitably transformed TU-game. We then introduce three types of invariance axioms for fixed player populations. The first type consists of composition axioms, and the second type is active-player consistency. Each of these two types yields a characterization of a subclass of the ELS values that contains the family of least-square values. Finally, the third type is nullified-game consistency: we define three such axioms, and each axiom yields a characterization of one of the Shapley, CIS, and ENSC values.

econ.TH↗

arXiv2025

Characterizations of Proportional Division Value in TU-Games via Fixed-Population Consistency

We study the proportional division value in TU-games, which distributes the grand coalition worth in proportion to the players' stand-alone worths. Focusing on fixed-population consistency, we characterize the proportional division value through three types of axioms: axioms concerning transformations of the grand coalition worth, composition axioms, and nullified-game consistency. The first type captures how payoffs respond when the grand coalition worth changes. The composition axioms require that the outcome be the same whether a game is solved directly or through a two-step procedure based on a reference allocation and an associated adjustment of the game. Nullified-game consistency requires that, when some players' payoffs are fixed, the solution for the remaining players in the adjusted game coincides with their original payoffs. Together with efficiency and/or fairness-related conditions where appropriate, these axioms characterize the proportional division value.

econ.TH↗

arXiv2025

Balanced contributions, consistency, and value for games with externalities

We consider fair and consistent extensions of the Shapley value for games with externalities. Based on the restriction identified by Casajus et al. (2024, Games Econ. Behavior 147, 88-146), we define balanced contributions, Sobolev's consistency, and Hart and Mas-Colell's consistency for games with externalities, and we show that these properties lead to characterizations of the generalization of the Shapley value introduced by Macho-Stadler et al. (2007, J. Econ. Theory 135, 339-356), that parallel important characterizations of the Shapley value.

econ.TH↗

arXiv2025

A Characterization of Egalitarian and Proportional Sharing Principles: An Efficient Extension Operator Approach

Some well-known solutions for cooperative games with transferable utility (TU-games), such as the Banzhaf value, the Myerson value, and the Aumann-Dreze value, fail to satisfy efficiency. Despite their desirable normative properties, this inefficiency motivates the search for a systematic method to restore efficiency while preserving their underlying normative structure. This paper proposes an efficient extension operator as a general approach to restore efficiency by extending any underlying solution to an efficient one. We consider novel axioms for those operators and characterize the egalitarian surplus sharing method and the proportional sharing method in a unified manner. As applications, we demonstrate the generality of our method by developing an efficient-fair extension of solutions for TU games with communication networks, as well as a variant for TU games with coalition structures.

econ.TH↗

arXiv2024

Random partitions, potential, value, and externalities

The Shapley value equals a player's contribution to the potential of a game. The potential is a most natural one-number summary of a game, which can be computed as the expected accumulated worth of a random partition of the players. This computation integrates the coalition formation of all players and readily extends to games with externalities. We investigate those potential functions for games with externalities that can be computed this way. It turns out that the potential that corresponds to the MPW solution introduced by Macho-Stadler et al. (2007, J. Econ. Theory 135, 339--356) is unique in the following sense. It is obtained as the expected accumulated worth of a random partition, it generalizes the potential for games without externalities, and it induces a solution that satisfies the null player property even in the presence of externalities.

econ.TH↗