39,374 research outputs found

    The Complexity of Fairness through Equilibrium

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    Competitive equilibrium with equal incomes (CEEI) is a well known fair allocation mechanism; however, for indivisible resources a CEEI may not exist. It was shown in [Budish '11] that in the case of indivisible resources there is always an allocation, called A-CEEI, that is approximately fair, approximately truthful, and approximately efficient, for some favorable approximation parameters. This approximation is used in practice to assign students to classes. In this paper we show that finding the A-CEEI allocation guaranteed to exist by Budish's theorem is PPAD-complete. We further show that finding an approximate equilibrium with better approximation guarantees is even harder: NP-complete.Comment: Appeared in EC 201

    A complex systems model for transformative supply chains in emerging markets

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    Purpose: Corporations operating global value chains must grapple with a multiplicity of ethical and practical considerations, most notably when value chains extend to emerging markets. Such contexts involve interactions with diverse stakeholders who possess the ability to impact supply chain performance, but who also bring conflicting needs, values and interests. The purpose of this paper is to outline a transformative model of supply chain fairness, arguing that adopting plural fairness principles and practices generates a higher fairness equilibrium which includes all affected stakeholders in the production of fairness outcomes, with consequent positive organizational and system level impacts. Design/methodology/approach: Through a philosophically informed overview of the literature on organizational fairness, the paper applies fairness to the management of supplier relations to identify the institutional features of ethically sustainable supply chains. The proposed conceptual model uses a complex adaptive systems approach (CADs), supplemented by describing the contribution of fairness norms and practices. Findings: This paper argues that a transformative approach to supply chain fairness can suggest new structures for interaction between firms, stakeholders, mediating institutions and governments. Originality/value: Emerging market supply chains are facing significant changes. Adopting a complex adaptive systems perspective upon stakeholder relationships, this paper offers insights from the theoretical literature on fairness, and proposes a normative model of supply chain fairness which accounts for both the normative and empirical aspects of relational complexity

    Spectrum sharing models in cognitive radio networks

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    Spectrum scarcity demands thinking new ways to manage the distribution of radio frequency bands so that its use is more effective. The emerging technology that can enable this paradigm shift is the cognitive radio. Different models for organizing and managing cognitive radios have emerged, all with specific strategic purposes. In this article we review the allocation spectrum patterns of cognitive radio networks and analyse which are the common basis of each model.We expose the vulnerabilities and open challenges that still threaten the adoption and exploitation of cognitive radios for open civil networks.L'escassetat de demandes d'espectre fan pensar en noves formes de gestionar la distribució de les bandes de freqüència de ràdio perquè el seu ús sigui més efectiu. La tecnologia emergent que pot permetre aquest canvi de paradigma és la ràdio cognitiva. Han sorgit diferents models d'organització i gestió de les ràdios cognitives, tots amb determinats fins estratègics. En aquest article es revisen els patrons d'assignació de l'espectre de les xarxes de ràdio cognitiva i s'analitzen quals són la base comuna de cada model. S'exposen les vulnerabilitats i els desafiaments oberts que segueixen amenaçant l'adopció i l'explotació de les ràdios cognitives per obrir les xarxes civils.La escasez de demandas de espectro hacen pensar en nuevas formas de gestionar la distribución de las bandas de frecuencia de radio para que su uso sea más efectivo. La tecnología emergente que puede permitir este cambio de paradigma es la radio cognitiva. Han surgido diferentes modelos de organización y gestión de las radios cognitivas, todos con determinados fines estratégicos. En este artículo se revisan los patrones de asignación del espectro de las redes de radio cognitiva y se analizan cuales son la base común de cada modelo. Se exponen las vulnerabilidades y los desafíos abiertos que siguen amenazando la adopción y la explotación de las radios cognitivas para abrir las redes civiles
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