{"title":"On three welfare properties of monopoly in bilateral exchange","authors":"Francesca Busetto , Giulio Codognato , Sayantan Ghosal , Damiano Turchet","doi":"10.1016/j.jmateco.2025.103147","DOIUrl":null,"url":null,"abstract":"<div><div>We establish three welfare properties of the model of monopoly introduced by Busetto et al. (2023), where one commodity is held only by the monopolist, represented as an atom, and the other is held only by small traders, represented by an atomless part. First, we prove that a monopoly allocation is Pareto optimal if and only if it is an allocation which corresponds to an efficiency equilibrium. Second, we reformulate a paradox, due to Shitovitz (1997), to show that for any monopoly allocation there is another core allocation, distinct from both a monopoly allocation or a Walras allocation, which is, utility-wise, advantageous for the monopolist and nonadvantageous for the small traders. Finally, we prove a theorem which shows that monopoly is advantageous for the monopolist and nonadvantageous for each trader in the atomless part with respect to all Walras allocations which are not monopoly allocations.</div></div>","PeriodicalId":50145,"journal":{"name":"Journal of Mathematical Economics","volume":"119 ","pages":"Article 103147"},"PeriodicalIF":0.7000,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Mathematical Economics","FirstCategoryId":"96","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0304406825000643","RegionNum":4,"RegionCategory":"经济学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"ECONOMICS","Score":null,"Total":0}
引用次数: 0
Abstract
We establish three welfare properties of the model of monopoly introduced by Busetto et al. (2023), where one commodity is held only by the monopolist, represented as an atom, and the other is held only by small traders, represented by an atomless part. First, we prove that a monopoly allocation is Pareto optimal if and only if it is an allocation which corresponds to an efficiency equilibrium. Second, we reformulate a paradox, due to Shitovitz (1997), to show that for any monopoly allocation there is another core allocation, distinct from both a monopoly allocation or a Walras allocation, which is, utility-wise, advantageous for the monopolist and nonadvantageous for the small traders. Finally, we prove a theorem which shows that monopoly is advantageous for the monopolist and nonadvantageous for each trader in the atomless part with respect to all Walras allocations which are not monopoly allocations.
期刊介绍:
The primary objective of the Journal is to provide a forum for work in economic theory which expresses economic ideas using formal mathematical reasoning. For work to add to this primary objective, it is not sufficient that the mathematical reasoning be new and correct. The work must have real economic content. The economic ideas must be interesting and important. These ideas may pertain to any field of economics or any school of economic thought.