Ching-jen Sun

Robustness of intermediate agreements and bargaining solutions

Most real-life bargaining is resolved gradually. During this process parties reach intermediate agreements. These intermediate agreements serve as disagreement points in subsequent rounds. We identify robustness criteria which are satisfied by three prominent bargaining solutions, the Nash, Proportional (and as a special case to the Egalitarian solution) and Discrete Raiffa solutions. We show that the “robustness of intermediate agreements” plus additional well-known and plausible axioms, provide novel axiomatizations of the above-mentioned solutions. Hence, we provide a unified framework for comparing these solutionsʼ bargaining theories.

Weakest collective rationality and the Nash bargaining solution

We propose a new axiom, weakest collective rationality (WCR) which is weaker than both weak Pareto optimality (WPO) in Nash’s (Econometrica 18:155–162, 1950) original characterization and strong individual rationality (SIR) in Roth’s (Math Oper Res 2:64–65, 1977) characterization of the Nash bargaining solution. We then characterize the Nash solution by symmetry (SYM), scale invariance (SI), independence of irrelevant alternatives (IIA) and our weakest collective rationality (WCR) axiom.

A note on the dynamics of incentive contracts

Laffont and Tirole (Econometrica 56:1153–1175) show that when uncertainty about an agent’s ability is small, the equilibrium must involve a large amount of pooling, but, whether the continuation equilibrium induced by an optimal first-period menu of contracts is partitional or not, remains unclear. They construct a non-partitional continuation equilibrium for a given first-period menu of contracts and conjecture that this continuation equilibrium need not be suboptimal for the whole game under small uncertainty. We show that, irrespective of the amount of uncertainty, this non-partitional continuation equilibrium generates a strictly smaller payoff for the principal than a different menu of contracts with a partitional continuation equilibrium. In this sense, Laffont and Tirole’s menu of contracts, giving rise to a non-partitional continuation equilibrium, is not optimal.

Dynamic Price Discrimination with Customer Recognition

Abstract This paper studies a general two-period model of product line pricing with customer recognition. Specifically, we consider a monopolist who can sell vertically differentiated products over two periods to heterogeneous consumers. Each consumer demands one unit of the product in each period. In the second period, the monopolist can condition the price–quality offers on the observed purchasing behavior in the first period. In this setup, the monopolist can price discriminate consumers in two dimensions: by quality as well as by purchase history. We fully characterize the monopolist’s optimal pricing strategy when there are two types of consumers. When the type space is a continuum, we show that there is no fully separating equilibrium, and some properties of the optimal contracts (price–quality pairs) are characterized within the class of partitional perfect Bayesian equilibria.

The Bargaining Correspondence: When Edgeworth Meets Nash

A new, more fundamental approach is proposed to the classical bargaining problem. The give-and-take feature in the negotiation process is explicitly modelled under the new framework. A compromise set consists of all allocations a player is willing to accept as agreement. We focus on the relationship between the rationality principles (arguments) adopted by players in making mutual concessions and the formation of compromise sets. The bargaining correspondence is then defined as the intersection of players’ compromise sets. We study the non-emptiness, symmetry, efficiency and single-valuedness of the bargaining correspondence, and establish its connection to the Nash solution. Our framework provides a rational foundation to Nash’s axiomatic approach.

ON THE TIMING OF PRODUCTION DECISIONS IN MONETARY ECONOMIES: TIMING OF PRODUCTION DECISIONS IN MONETARY ECONOMIES

In most macroeconomic models inflation tends to be harmful. In this paper we show that by simply changing the timing of production decisions by firms from “on demand” to “in advance”, some inflation can boost welfare as long as goods are sufficiently perishable. The main conclusion from this research is that by effectively hiding the strategic interaction between supply and demand, assuming production on demand is not without loss of generality.

Dynamic price dispersion in Bertrand–Edgeworth competition

This paper studies a dynamic oligopoly model of price competition under demand uncertainty. Sellers are endowed with one unit of the good and compete by posting prices in every period. Buyers each demand one unit of the good and have a common reservation price. They have full information regarding the prices posted by each firm in the market; hence, search is costless. The number of buyers coming to the market in each period is random. Demand uncertainty is said to be high if there are at least two non-zero demand states that give a seller different option values of waiting to sell. Our model features a unique symmetric Markov perfect equilibrium in which price dispersion prevails if and only if the degree of demand uncertainty is high. Several testable theoretical implications on the distribution of market prices are derived.