arXiv subjects

Ana Meca

Publications and source records attributed to Ana Meca.

15 recordsLinked to original sources

arXiv2025

The Shapley value and the strength of weak players in Big Boss games

Big Boss Games represent a specific class of cooperative games where a single veto player, known as the Big Boss, plays a central role in determining resource allocation and maintaining coalition stability. In this paper, we introduce a novel allocation scheme for Big Boss games, based on two classical solution concepts: the Shapley value and the $\tau$-value. This scheme generates a coalitionally stable allocation that effectively accounts for the contributions of weaker players. Specifically, we consider a diagonal of the core that includes the Big Boss's maximum aspirations, the $\tau$-value, and those of the weaker players. From these allocations, we select the one that is closest to the Shapley value, referred to as the Projected Shapley Value allocation (PSV allocation). Through our analysis, we identify a new property of Big Boss games, particularly the relationship between the allocation discrepancies assigned by the $\tau$-value and the Shapley value, with a particular focus on the Big Boss and the other players. Additionally, we provide a new characterization of convexity within this context. Finally, we conduct a statistical analysis to assess the position of the PSV allocation within the core, especially in cases where computing the Shapley value is computationally challenging.

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arXiv2024

HarvestTech agriculture cooperatives: Beneficiaries and compensations

Agricultural industries face increasing pressure to optimize efficiency and reduce costs in a competitive and resource-constrained global market. As firms seek innovative ways to enhance productivity, cooperative strategies have emerged as a promising solution to address these challenges. In this context, game theory provides a powerful framework for analyzing and structuring such cooperative efforts, ensuring that each firm's contribution is fairly rewarded. This paper presents an innovative approach to address challenges in agricultural crop processing through inter-firm cooperation. A new class of totally balanced games is introduced, which models the strategic interactions among companies processing agricultural products. The objective is to identify profit allocations that fairly compensate firms contributing to cost reduction and surplus processing for others. To achieve this, the allocations resulting from each type of compensation will be thoroughly examined, and a coalitionally stable compensation procedure will be established. The study demonstrates the feasibility and effectiveness of cooperative strategies for optimizing agricultural processes. Lastly, the findings will be applied to a case study.

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arXiv2024

Cooperative Agri-Food Export under Minimum Quantity Commitments

International trade can be a profitable business for agri-food communities. However, access to international markets can be costly and thus unattainable for small and medium sized enterprises (SMEs). This problem is exacerbated under trade policies which require minimum quantity commitments (MQCs) on export volumes, e.g., licensing tariff rate quota (TRQ) mechanisms. We show how cooperative exporting among agri-food SMEs can tackle the barriers posed by the MQCs, and give market access to a broader range of SMEs. We formulate a class of cooperative games associated with these situations and find a gain-sharing mechanism that result in allocations in their corresponding cores. Thus, grand coalitions of cooperative exporting SMEs can form in stable manners. This allocation rule shares the export surplus only among the "essential" SME exporters, that is, the players who are sufficiently cost efficient. Thus, less cost efficient "complimentary" SMEs whose capacities are needed to maintain MQCs receive no benefit from collaborative exporting and their participation have to be altruistic. We propose two modifications to our original allocation rule to share a portion of export surplus among the complementary SMEs through taxing the essential SMEs: the first through egalitarian, and the second through revenue-based rates. We compare the performance of these allocations with the numerical examples and discuss their practical implications.

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arXiv2024

Evaluating the impact of items and cooperation in inventory models with exemptable ordering costs

In this paper we introduce and analyse, from a game theoretical perspective, several multi-agent or multi-item continuous review inventory models in which the buyers are exempted from ordering costs if the price of their orders is greater than or equal to a certain amount. For all models we obtain the optimal ordering policy. We first analyse a simple model with one firm and one item. Then, we study a model with one firm and several items, for which we design a procedure based on cooperative game theory to evaluate the impact of each item on the total cost. Then, we deal with a model with several firms and one item for each firm, for which we characterise a rule to allocate the total cost among the firms in a coalitionally stable way. Finally, we discuss a model with several firms and several items, for which we characterise a rule to allocate the total cost among the firms in a coalitionally stable way and to evaluate the impact of each item on the cost that would be payable to each firm when using the allocation rule. All the concepts and results of this article are illustrated using data from a case study.

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arXiv2024

On benefits of cooperation under strategic power

We introduce a new model involving TU-games and exogenous structures. Specifically, we consider that each player in a population can choose an element in a strategy set and that, for every possible strategy profile, a TU-game is associated with the population. This is what we call a TU-game with strategies. We propose and characterize the maxmin procedure to map every game with strategies to a TU-game. We also study whether or not the relevant properties of TU-games are transmitted by applying the maxmin procedure. Finally, we examine two relevant classes of TU-games with strategies: airport and simple games with strategies.

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arXiv2024

Dynamic Realization Games in Newsvendor Inventory Centralization

Consider a set N of n (>1) stores with single-item and single-period nondeterministic demands like in a classic newsvendor setting with holding and penalty costs only. Assume a risk-pooling single-warehouse centralized inventory ordering option. Allocation of costs in the centralized inventory ordering corresponds to modelling it as a cooperative cost game whose players are the stores. It has been shown that when holding and penalty costs are identical for all subsets of stores, the game based on optimal expected costs has a non empty core (Hartman et. al., 2000, Muller \textit{et. al.}, 2002). In this paper we examine a related inventory centralization game based on demand realizations that has, in general, an empty core even with identical penalty and holding costs (Hartman and Dror, 2005). We propose a repeated cost allocation scheme for dynamic realization games based on allocation processes introduced by Lehrer (2002a). We prove that the cost subsequences of the dynamic realization game process, based on Lehrer's rules, converge almost surely to either a least square value or the core of the expected game. We extend the above results to more general dynamic cost games and relax the independence hypothesis of the sequence of players' demands at different stages.

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arXiv2024

p-additive games: a class of totally balanced games arising from inventory situations with temporary discounts

We introduce a new class of totally balanced cooperative TU games, namely p -additive games. It is inspired by the class of inventory games that arises from inventory situations with temporary discounts (Toledo, 2002) and contains the class of inventory cost games (Meca et al. 2003). It is shown that every p-additive game and its corresponding subgames have a nonempty core. We also focus on studying the character concave or convex and monotone of p-additive games. In addition, the modified SOC-rule is proposed as a solution for p-additive games. This solution is suitable for p-additive games since it is a core-allocation which can be reached through a population monotonic allocation scheme. Moreover, two characterizations of the modified SOC-rule are provided.

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arXiv2024

Cooperation and profit allocation in distribution chains

We study the coordination of actions and the allocation of profit in supply chains under decentralized control in which a single supplier supplies several retailers with goods for replenishment of stocks. The goal of the supplier and the retailers is to maximize their individual profits. Since the outcome under decentralized control is inefficient, cooperation among firms by means of coordination of actions may improve the individual profits. Cooperation is studied by means of cooperative game theory. Among others we show that the corresponding games are balanced and we propose a stable solution concept for these games.

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arXiv2024

Production-Inventory games: a new class of totally balanced combinatorial optimization games

In this paper we introduce a new class of cooperative games that arise from production-inventory problems. Several agents have to cover their demand over a finite time horizon and shortages are allowed. Each agent has its own unit production, inventory-holding and backlogging cost. Cooperation among agents is given by sharing production processes and warehouse facilities: agents in a coalition produce with \ the cheapest production cost and store with the cheapest inventory cost. We prove that the resulting cooperative game is totally balanced and the Owen set reduces to a singleton: the Owen point. Based on this type of allocation we find a population monotonic allocation scheme for this class of games. Finally, we point out the relationship of the Owen point with other well-known allocation rules such as the nucleolus and the Shapley value.

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arXiv2024

Production-inventory games and pmas games: characterizations of the Owen point

Production-inventory games were introduced in Guardiola et al. (2007) as a new class of totally balanced combinatorial optimization games. From among all core-allocations, the Owen point was proposed as a specifically appealing solution. In this paper we study some relationships of the class of production-inventory games and other classes of new and known games. In addition, we propose three axiomatic characterizations of the Owen point. We use eight axioms for these characterizations, among those, inessentiality and additivity of players' demands are used for the first time in this paper.

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arXiv2024

Unitary Owen points in cooperative lot-sizing models with backlogging

Cooperative lot-sizing models with backlogging and heterogeneous costs are studied in Guardiola et al. (2020). In this model several firms participate in a consortium aiming at satisfying their demand over the planing horizon with minimal operation cost. Each firm uses the best ordering channel and holding technology provided by the participants in the consortium. The authors show that there are always fair allocations of the overall operation cost among the firms so that no group of agents profit from leaving the consortium. This paper revisits those cooperative lot-sizing models and presents a new family of cost allocations, the unitary Owen points. This family is an extension of the Owen set which enjoys very good properties in production-inventory proble, introduced by Guardiola et al. (2008). Necessary and sufficient conditions are provided for the unitary Owen points to be fair allocations. In addition, we provide empirical evidence, throughout simulation, showing that the above condition is fulfilled in most cases. Additionally, a relationship between lot-sizing games and a certain family of production-inventory games, through Owen's points of the latter, is described. This interesting relationship enables to easily construct a variety of fair allocations for cooperative lot-sizing models.

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arXiv2023

Profit allocation in agricultural supply chains: exploring the nexus of cooperation and compensation

In this paper, we focus on decentralized agricultural supply chains consisting of multiple non-competing distributors satisfying the demand of their respective markets. These distributors source a single product from a farmer through an agricultural cooperative, operating in a single period. The agents have the ability to coordinate their actions to maximize their profits, and we use cooperative game theory to analyze cooperation among them. The distributors can engage in joint ordering, increasing their order size, which leads to a decrease in the price per kilogram. Additionally, distributors have the opportunity to cooperate with the farmer, securing a reduced price per kilogram at the cost price, while compensating the farmer for any kilograms not acquired in the cooperation agreement. We introduce multidistributor-farmer games and we prove that all the agents have incentives to cooperate. We demonstrate the existence of stable allocations, where no subgroup of agents can be better off by separating. Moreover, we propose and characterize a distribution of the total profit that justly compensates the contribution of the farmer in any group of distributors. Finally, we explore the conditions under which the farmer can be compensated in order to maximize their revenues when cooperating with all players.

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arXiv2023

Allocating the surplus induced by cooperation in distribution chains with multiple suppliers and retailers

The coordination of actions and the allocation of profit in supply chains under decentralized control play an important role in improving the profits of retailers and suppliers in the chain. We focus on supply chains under decentralized control in which noncompeting retailers can order from multiple suppliers to replenish their stocks. Suppliers' production capacity is bounded. The goal of the firms in the chain is to maximize their individual profits. As the outcome under decentralized control is inefficient, coordination of actions between cooperating agents can improve individual profits. Cooperative game theory is used to analyze cooperation between agents. We define multi-retailer-supplier games and show that agents can always achieve together an optimal profit and they have incentives to cooperate and to form the grand coalition. Moreover, we show that there always exist stable allocations of the total profit among the firms upon which no coalition can improve. Then we propose and characterize a stable allocation of the total surplus induced by cooperation.

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arXiv2021

Cooperation in lot-sizing problems with heterogeneous costs: the effect of consolidated periods

We consider a cooperative game defined by an economic lot-sizing problem with heterogeneous costs over a finite time horizon, in which each firm faces demand for a single product in each period and coalitions can pool orders. The model of cooperation works as follows: ordering channels and holding and backlogging technologies are shared among the members of the coalitions. This implies that each firm uses the best ordering channel and holding technology provided by the participants in the consortium. That is, they purchase, hold inventory, pay backlogged demand and make orders at the minimum cost of the coalition members. Thus, firms aim at satisfying their demand over the planing horizon with minimal operation cost. Our contribution is to show that there exist fair allocations of the overall operation cost among the firms so that no group of agents profit from leaving the consortium. Then we propose a parametric family of cost allocations and provide sufficient conditions for this to be a stable family against coalitional defections of firms. Finally, we focus on those periods of the time horizon that are consolidated and we analyze their effect on the stability of cost allocations.

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arXiv2020

Quid Pro Quo allocations in Production-Inventory games

The concept of Owen point, introduced in Guardiola et al. (2009), is an appealing solution concept that for Production-Inventory games (PI-games) always belongs to their core. The Owen point allows all the players in the game to operate at minimum cost but it does not take into account the cost reduction induced by essential players over their followers (fans). Thus, it may be seen as an altruistic allocation for essential players what can be criticized. The aim this paper is two-fold: to study the structure and complexity of the core of PI-games and to introduce new core allocations for PI-games improving the weaknesses of the Owen point. Regarding the first goal, we advance further on the analysis of PI-games and we analyze its core structure and algorithmic complexity. Specifically, we prove that the number of extreme points of the core of PI-games is exponential on the number of players. On the other hand, we propose and characterize a new core-allocation, the Omega point, which compensates the essential players for their role on reducing the costs of their fans. Moreover, we define another solution concept, the Quid Pro Quo set (QPQ-set) of allocations, which is based on the Owen and Omega points. Among all the allocations in this set, we emphasize what we call the Solomonic QPQ allocation and we provide some necessary conditions for the coincidence of that allocation with the Shapley value and the Nucleolus.

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