arXiv subjects

Michiko Ogaku

Publications and source records attributed to Michiko Ogaku.

3 recordsLinked to original sources

arXiv2026

Full Subgame-Perfect Implementation of Optimal Risk Sharing on an Infinite Menu

Can a welfare-maximizing risk-sharing rule be implemented in a decentralized community? We extend the price-and-choose (P&C) mechanism of Echenique and Núñez (2025), in which players sequentially post price schedules and the last mover selects an allocation, from finite choice sets to an infinite risk-sharing menu. Each allocation is modeled as a bounded random vector that redistributes an aggregate loss $X=\sum_i X_i$, and the menu is weak$^\ast$ compact. In subgame-perfect equilibrium, the extended mechanism fully implements the set of allocations that maximize aggregate monetary utility over the admissible menu. The result remains valid when players hold heterogeneous weak$^\ast$-compact credal sets of finitely additive probabilities, or charges, dominated by a reference probability, provided that the induced max-min monetary utilities are uniformly Lipschitz on the menu. We also adapt their first-mover auction to this infinite-menu, multiple-prior environment. Under complete information about all payoff-relevant primitives, the auction admits a symmetric equilibrium that equalizes ex-ante surplus. The resulting procedure therefore achieves optimal and fair risk sharing under heterogeneous priors without trusted third-party enforcement once participants commit to it.

econ.TH↗

arXiv2026

Insuring uninsurable income

We study dynamic mechanism design in a pure-exchange economy with privately observed idiosyncratic income. In the standard infinitely lived hidden-income benchmark of Green (1987) and Thomas-Worrall (1990), constrained-efficient allocations exhibit immiseration. We propose a simple recursive mechanism -- adapted from Marcet-Marimon (1992) -- that shifts each income shock forward by one period, keeps promised utilities in a bounded set, and, under a transparent ``moderate risk-aversion'' condition, delivers sequential efficiency. In a stationary \emph{overlapping-generations} setting, we further show that under additional symmetry and curvature assumptions, a second-order approximation yields a sufficient condition for period-by-period budget balance; early cohorts pre-fund later transfers; for suitable initial promises, all cohorts are better off than under autarky. Our analysis uses a single state (promised utility), closed-form transfers, and a Bellman verification.

econ.TH↗

arXiv2025

Linguistic Indirectness in Public Cheap-Talk Games

We study linguistic indirectness when speakers attend to social ties. Social ties are modeled by a graph, and conferences are the sets of nodes that hear a message. Conference worth is a distance polynomial on the graph; allocations are given by the Myerson value of the conference-restricted worth, which yields the bargaining-power components for each participant. Aggregating these components gives an effective bias that, via a Partition-Threshold rule, pins down the number of equilibrium message partitions in a cheap talk game. Results: (i) among trees, stars maximize worth, leading to weakly fewer equilibrium partitions; (ii) on stars, we derive closed-form effective biases, with a witness-hub marginal effect of adding leaves changing sign at $δ^{\ast}=0.6$; (iii) for two stars joined by one link, two-star (hub-hub) vs big-star (hub-leaf) precision flips at 8/15 for the same number of nodes; private leaf-leaf conferences are most informative.

econ.TH↗