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

Production-inventory games were introduced in [Guardiola, L.A., Meca, A., Puerto, J. (2008). Production-Inventory games: A new class of totally balanced combinatorial optimization games. Games Econom. Behav. doi:10.1016/j.geb.2007.02.003] 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

Cooperation on capacitated inventory situations with fixed holding costs

[Abstract] In this paper we analyze a situation in which several firms deal with inventory problems concerning the same type of product. We consider that each firm uses its limited capacity warehouse for storing purposes and that it faces an economic order quantity model where storage costs are irrelevant (and assumed to be zero) and shortages are allowed. In this setting, we show that firms can save costs by placing joint orders and obtain an optimal order policy for the firms. Besides, we identify an associated class of costs games which we show to be concave. Finally, we introduce and study a rule to share the costs among the firms which provides core allocations and can be easily computed.Ministerio de Ciencia e Innovación; MTM2011-23205Galicia. Consellería de Economía e Industria; INCITE09-207-064-PRComunidad Valenciana. Generalidad; ACOMP/2014Ministerio de Ciencia e Innovación; MTM2011-27731-C0

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.Ministerio de Economía y Competitividad | Ref. PGC2018-097965-B-100Ministerio de Economía y Competitividad | Ref. MTM2017-87197-C3-1-PMinisterio de Economía y Competitividad | Ref. MTM2017-87197-C3-2-PMinisterio de Economía y Competitividad | Ref. MTM2014-53395-C3-1-PMinisterio de Economía y Competitividad | Ref. MTM2014-53395-C3-3-PMinisterio de Economía y Competitividad | Ref. MTM2014-54199-PXunta de Galicia | Ref. ED431C-2016-015Xunta de Galicia | Ref. ED431C-2016-040Xunta de Galicia | Ref. ED431G/0

Efficient Effort Equilibrium in Cooperation with Pairwise Cost Reduction

There are multiple situations in which bilateral interaction between agents results in considerable cost reductions. Such interaction can occur in settings where agents are interested in sharing resources, knowledge or infrastructures. Their common purpose is to obtain individual advantages, e.g. by reducing their respective individual costs. Achieving this pairwise cooperation often requires the agents involved to make some level of effort. It is natural to think that the amount by which one agent could reduce the costs of the other may depend on how much effort the latter exerts. In the first stage, agents decide how much effort they are to exert, which has a direct impact on their pairwise cost reductions. We model this first stage as a non-cooperative game, in which agents determine the level of pairwise effort to reduce the cost of their partners. In the second stage, agents engage in a bilateral interaction between independent partners. We study this bilateral cooperation as a cooperative game in which agents reduce each other's costs as a result of cooperation, so that the total reduction in the cost of each agent in a coalition is the sum of the reductions generated by the rest of the members of that coalition. In the non-cooperative game that precedes cooperation with pairwise cost reduction, the agents anticipate the cost allocation that results from the cooperative game in the second stage by incorporating the effect of the effort exerted into their cost functions. Based on this model, we explore the costs, benefits, and challenges associated with setting up a pairwise effort network. We identify a family of cost allocations with weighted pairwise reduction which are always feasible in the cooperative game and contain the Shapley value. We show that there are always cost allocations with weighted pairwise reductions that generate an optimal level of efficient effort and provide a procedure for finding the efficient effort equilibrium

Cost-Analysis of Subcutaneous vs Intravenous Administration of Natalizumab Based on Patient Care Pathway in Multiple Sclerosis in Spain

Análisis de costes; Administración subcutánea; Esclerosis múltipleAnàlisi de costos; Administració subcutània; Esclerosi múltipleCost-analysis; Subcutaneous administration; Multiple sclerosisIntroduction A subcutaneous (SC) formulation of natalizumab has been recently authorised for multiple sclerosis patients. This study aimed to assess the implications of the new SC formulation, and to compare the annual treatment costs of SC versus intravenous (IV) natalizumab therapy from both the Spanish healthcare system (direct health cost) and the patient (indirect cost) perspectives. Methods A patient care pathway map and a cost-minimisation analysis were developed to estimate SC and IV natalizumab annual costs over a 2-year time horizon. Considering the patient care pathway and according to natalizumab experience (IV) or estimation (SC), a national expert panel involving neurologists, pharmacists, and nurses provided information/data regarding resource consumption for drug and patient preparation, administration, and documentation. One hour of observation was applied to the first six (SC) or 12 (IV) doses, and 5 min for successive doses. The Day hospital (infusion suite) facilities at a reference hospital were considered for IV administrations and the first six SC injections. For successive SC injections, either a reference hospital or regional hospital in a consulting room was considered. Productivity time associated with travel (56 min to reference hospital, 24 min to regional hospital) and waiting time pre- and post-treatment (SC 15 min, IV 25 min) were assessed for patients and caregivers (accompanying 20% of SC and 35% of IV administrations). National salaries for healthcare professionals were used for cost estimation (€, year 2021). Results At years 1 and 2, total time and cost savings (excluding drug acquisition cost) per patient, driven by saving on administration and patient and caregiver productivity for SC at a reference hospital versus IV at a reference hospital, were 116 h (a reduction of 54.6%) and €3682.82 (a reduction of 66.2%). In the case of natalizumab SC at a regional hospital, the total time and cost saving were 129 h (a reduction of 60.6%) and €3883.47 (a reduction of 69.8%). Conclusions Besides the potential benefits of convenient administration and improving work–life balance, as suggested by the expert panel, natalizumab SC was associated with cost savings for the healthcare system by avoiding drug preparation, reducing administration time, and freeing up infusion suite capacity. Additional cost savings could be derived with regional hospital administration of natalizumab SC by reducing productivity loss

SARS-CoV-2 Infection in Multiple Sclerosis

To understand COVID-19 characteristics in people with multiple sclerosis (MS) and identify high-risk individuals due to their immunocompromised state resulting from the use of disease-modifying treatments. Retrospective and multicenter registry in patients with MS with suspected or confirmed COVID-19 diagnosis and available disease course (mild = ambulatory; severe = hospitalization; and critical = intensive care unit/death). Cases were analyzed for associations between MS characteristics and COVID-19 course and for identifying risk factors for a fatal outcome. Of the 326 patients analyzed, 120 were cases confirmed by real-time PCR, 34 by a serologic test, and 205 were suspected. Sixty-nine patients (21.3%) developed severe infection, 10 (3%) critical, and 7 (2.1%) died. Ambulatory patients were higher in relapsing MS forms, treated with injectables and oral first-line agents, whereas more severe cases were observed in patients on pulsed immunosuppressors and critical cases among patients with no therapy. Severe and critical infections were more likely to affect older males with comorbidities, with progressive MS forms, a longer disease course, and higher disability. Fifteen of 33 patients treated with rituximab were hospitalized. Four deceased patients have progressive MS, 5 were not receiving MS therapy, and 2 were treated (natalizumab and rituximab). Multivariate analysis showed age (OR 1.09, 95% CI, 1.04-1.17) as the only independent risk factor for a fatal outcome. This study has not demonstrated the presumed critical role of MS therapy in the course of COVID-19 but evidenced that people with MS with advanced age and disease, in progressive course, and those who are more disabled have a higher probability of severe and even fatal diseas

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio

Cost allocation in inventory transportation systems

In this paper we deal with the cost allocation problem arising in an inventory transportation system with a single item and multiple agents that place joint orders using an EOQ policy. In our problem, the fixed order cost of each agent is the sum of a first component (common to all agents) plus a second component which depends on the distance from the agent to the supplier. We assume that agents are located on a line route, in the sense that if any subgroup of agents places a joint order, its fixed cost is the sum of the first component plus the second component of the agent in the group at maximal distance from the supplier. For these inventory transportation systems we introduce and characterize a rule which allows us to allocate the costs generated by the joint order. This rule has the same flavor as the Shapley value, but requires less computational effort. We show that our rule has good properties from the point of view of stability.Ministerio de Ciencia e Innovación | Ref. CSD2006-00032Ministerio de Ciencia e Innovación | Ref. MTM2008-06778-C02-01Ministerio de Ciencia e Innovación | Ref. ECO2008-03484-C02-02/ECOGeneralitat Valenciana | Ref. ACOMP/2011/129Xunta de Galicia | Ref. INCITE09-207- 064-PR

Cooperation on capacitated inventory situations with fixed holding costs

In this paper we analyze a situation in which several firms deal with inventory problems concerning the same type of product. We consider that each firm uses its limited capacity warehouse for storing purposes and that it faces an economic order quantity model where storage costs are irrelevant (and assumed to be zero) and shortages are allowed. In this setting, we show that firms can save costs by placing joint orders and obtain an optimal order policy for the firms. Besides, we identify an associated class of costs games which we show to be concave. Finally, we introduce and study a rule to share the costs among the firms which provides core allocations and can be easily computed.Ministerio de Ciencia e Innovación | Ref. MTM2008-06778-C02-01Ministerio de Ciencia e Innovación | Ref. ECO2008-03484-C02-02Ministerio de Ciencia e Innovación | Ref. MTM2011-23205Ministerio de Ciencia e Innovación | Ref. MTM2011-27731-C03Xunta de Galicia | Ref. INCITE09-207-064-PRGeneralitat Valenciana | Ref. ACOMP/2013/09

Cooperative game theory and inventory management

Supply chain management is related to the coordination of materials, products and information flows among suppliers, manufacturers, distributors, retailers and customers involved in producing and delivering a final product or service. In this setting the centralization of inventory management and coordination of actions, to further reduce costs and improve customer service level, is a relevant issue. In this paper, we provide a review of the applications of cooperative game theory in the management of centralized inventory systems. Besides, we introduce and study a new model of centralized inventory: a multi-client distribution network.Ministerio de Ciencia e Innovación, FEDER | Ref. ECO2008-03484-C02-02Ministerio de Ciencia e Innovación, FEDER | Ref. MTM2008-06778-C02-01Xunta de Galicia | Ref. INCITE09-207-064-P