Vladimir Davidiuk, Yuriy Dementiev, Artur Ignatiev
et al.
We study the problem of fairly and efficiently allocating indivisible goods among agents with additive valuations. We focus on envy-freeness up to any good (EFX) -- an important fairness notion in fair division of indivisible goods. A central open question in this field is whether EFX allocations always exist for any number of agents. While prior work has established EFX existence for settings with at most three distinct valuations (Prakash HV et al. 2025) and for two types of goods (Gorantla, Marwaha, and Velusamy 2023), the general case remains unresolved. In this paper, we extend the existent knowledge by proving that EFX allocations satisfying Pareto optimality (PO) always exist and can be computed in quasiliniear time when there are two types of goods, given that the valuations are positive. This result strengthens the existing work of (Gorantla, Marwaha, and Velusamy 2023), which only guarantees the existence of EFX allocations without ensuring Pareto optimality. Our findings demonstrate a fairly simple and efficient algorithm constructing an EFX+PO allocation.
We study the problem of allocating indivisible goods among agents with additive valuation functions to achieve both fairness and efficiency under the constraint that each agent receives exactly the same number of goods (the \emph{balanced constraint}). While this constraint is common in real-world scenarios such as team drafts or asset division, it significantly complicates the search for allocations that are both fair and efficient. Envy-freeness up to one good (EF1) is a well-established fairness notion for indivisible goods. Pareto optimality (PO) and its stronger variant, fractional Pareto optimality (fPO), are widely accepted efficiency criteria. Our main contribution establishes both the existence and polynomial-time computability of allocations that are simultaneously EF1 and fPO under balanced constraints in two fundamental cases: (1) when each agent has a personalized bivalued valuation, and (2) when agents have at most two distinct valuation types,. Our algorithms leverage novel applications of maximum-weight matching in bipartite graphs and duality theory, providing the first polynomial-time solutions for these cases and offering new insights for constrained fair division problems.
The costly provision of public goods serves as a model problem for the evolution of cooperative behavior, presenting a social dilemma between the collective benefits of shared resources and the individual incentive to free-ride in resource production. The spatial structure of populations can also impact cooperation over public goods, as diffusion of public goods and intentional motion of individuals towards regions with greater resources can interact with population and public goods dynamics to produce heterogeneous patterns in the spatial distribution of strategies and resources. In this paper, we build off a model introduced by Young and Belmonte for the reaction dynamics of interacting individuals and explicit public good, deriving a system of PDEs that describes the spatial profiles of strategies and the public good in the presence of both diffusive motion of individuals and resources and chemotaxis-like directed motion of individuals in response to gradients in the concentration of public goods. Through linear stability analysis, we show that spatial patterns in strategic and public goods profiles can emerge due to either Turing instability with high defector diffusivity or a directed-motion instability through strong sensitivity of cooperators towards increasing resource concentration. We further explore the emergent spatial patterns with a mix of weakly nonlinear stability analysis and numerical simulation, showing that diffusion-driven instability appears to increase cooperation and public goods across the spatial domain, while directed motion of cooperators towards regions with great public goods provision tends to decrease cooperation and environmental quality across the environment.
The management of transportation, warehousing, and distribution of perishable goods from the farm to consumers zone has been major concern in the agri-food industry, considering decay of products and effect of methane gas to the environment from this decayed product. A multi-period, strategic and tactical planning model was developed to take care of shipment route for these perishable goods from the farm gate to the consumer’s zone with different cold-hubs via different routes options. The S-T model addressed sensitivity and ambiguity associated with seasonal demand and product loss due to delay in shipment, to ensure timely and efficient delivery of products. Five contradicting objectives (Profit, Power Rating, Credit Performance, Response time and Distributors Reputation) were optimized, initially a single objective optimization was employed to attain a single best solution and then a multi-objective optimization to achieve a compromise solution using Chebyshev goal programming. The model bases its analysis on five objective factors: customer response time, power rating, credit performance, distributor reputation, and profit. Following the tactical and strategic requirements in the aforementioned S-T framework, only three distribution centers of mixed capacity were established for a mid-term planning. In addition to determining the location and capacity of each cold hub, the research model was also able to determine which customers, if any, should be moved to independent distributors.
Amalia Polydoropoulou, Adonis Velegrakis, Georgios Papaioannou
et al.
This paper develops a composite Port Resilience Index (PRI) to address the specific vulnerabilities and operational challenges of Greek ports in respect to climate-related hazards. Based on stakeholder engagement from Living Labs in three key ports (Chios, Volos, and Heraklion), the study identifies and quantifies the impacts of climate-related hazards using a structured Multi-Criteria Decision Analysis (MCDA) framework. Specifically, the Analytic Hierarchy Process (AHP) is used to elicit expert judgments and prioritize resilience criteria across five impact areas: Infrastructure, Operational and Supply Chain, Digital, Socioeconomic and Environmental, and Governance and Compliance Resilience. Nineteen indicators, spanning physical infrastructure, operational reliability, digital readiness, and socioeconomic factors, are evaluated to construct a composite PRI, enabling a transparent and stakeholder-informed benchmarking process. The results reveal significant variation in resilience levels, with Volos exhibiting the highest PRI (0.643) and Chios the lowest (0.217), thereby highlighting port-specific adaptation needs. Conducting a sensitivity analysis we validated the robustness of the PRI construction methodology across various weighting scenarios. The key contributions of this study are: (i) the development of a replicable, data-driven PRI model; (ii) the integration of local stakeholder input via Living Labs; and (iii) the innovative application of AHP to climate resilience planning in the port industry. Moreover, while focused on Greek ports, the framework offers a replicable model that can be adapted to other regions facing similar climate challenges. Ultimately, the PRI serves as both a diagnostic and strategic tool to guide policy, investment, and disaster preparedness in ports
In real-world social and economic systems, the provisioning of public goods generally entails continuous interactions among individuals, with decisions to cooperate or defect being influenced by dynamic factors such as timing, resource availability, and the duration of engagement. However, the traditional public goods game ignores the asynchrony of the strategy adopted by players in the game. To address this problem, we propose a spatial public goods game that integrates an M/M/1 queueing system to simulate the dynamic flow of player interactions. We use a birth-death process to characterize the stochastic dynamics of this queueing system, with players arriving following a Poisson process and service times being exponentially distributed under a first-come-first-served basis with finite queue capacity. We also incorporate reputation so that players who have cooperated in the past are more likely to be chosen for future interactions. Our research shows that a high arrival rate, low service rate, and the reputation mechanism jointly facilitate the emergence of cooperative individuals in the network, which thus provides an interesting and new perspective for the provisioning of public goods.
Frederik C. Rust, Leslie R. Sampson, Adriana A. Cachia
et al.
Background: Foresight can be used to define futuristic orientated research and development (RD) that is required to position the road transport sector for a challenging future.
Objectives: To develop a set of futuristic RD projects that could be added to a balanced SANRAL RD portfolio to position SANRAL and the transport sector for the future on a 15-year horizon.
Method: Inputs into and ranking of the drivers, trends and technologies that will impact the transport sector were obtained from interviews with eminent thinkers, participants in workshops and a survey leading to five potential future scenarios. Qualitative and quantitative data analysis yielded several key solutions (KSs) and key interventions (KIs) to position the sector. This was complemented with the novel use of technology trees to analyse the linkages between new and existing knowledge and to identify gaps in knowledge and subsequently the identification of key RD opportunities.
Results: Through backcasting from the desired future scenario as well as using 412 stakeholder inputs, 12 KSs and 61 KIs were defined and ranked. The top 30, most futuristic KIs were analysed using 18 hierarchical technology trees to define RD opportunities.
Conclusion: The analysis emphasised the importance of new technologies such as data science, machine learning, smart transport and advanced materials to position the sector.
Contribution: The use of a novel, structured technology foresight approach that utilises scenario development combined with hierarchical technology trees was demonstrated. To position the road transport sector for a challenging future, 12 new thematic KSs and 61 KIs were developed.
Shipment of goods. Delivery of goods, Transportation and communications
Giovana de Fátima Baruffi, Eliane M. Octaviano Martins
No presente artigo é proposta a mitigação da presunção de legitimidade e veracidade do ato administrativo sancionador aduaneiro como medida para assegurar direitos e garantias constitucionais do administrado no processo administrativo sancionatório aduaneiro – dentre as quais, a garantia ao devido processo legal.
A relativização da presunção de legitimidade e veracidade do ato administrativo sancionador aduaneiro consiste primordialmente no dever da Administração Pública de comprovar a ocorrência do fato imputável em face do administrado como condição para legitimar o ato administrativo sancionatório, sob pena de nulidade.
No Estado Democrático de Direito, a penalização aduaneira deve observar a presunção de boa-fé do administrado, o devido processo legal, a verificação da culpabilidade, a individualização e a dosimetria da pena, assim como a proporcionalidade na aplicação de sanções.
A mitigação da presunção de veracidade dos atos administrativos sancionatórios aduaneiros constitui medida imprescindível à garantia de segurança jurídica nas operações de comércio exterior, assegurando ao interveniente importador o adequado controle de riscos e condições de previsibilidade e segurança para planejar e investir – o que impacta diretamente no crescimento produtivo e econômico do país.
Allocating items in a fair and economically efficient manner is a central problem in fair division. We study this problem for agents with additive preferences, when items are all goods or all chores, divisible or indivisible. The celebrated notion of Nash welfare is known to produce fair and efficient allocations for both divisible and indivisible goods; there is no known analogue for dividing chores. The Nash welfare objective belongs to a large, parameterized family of objectives called the p-mean welfare functions, which includes other notable members, like social welfare and egalitarian welfare. However, among the members of this family, only the Nash welfare produces fair allocations for goods. Incidentally, Nash welfare is also the only member that satisfies the axiom of scale invariance, which is crucially associated with its fairness properties. We define the class of "normalized p-mean" objectives, which imparts the missing key axiom of scale invariance to the p-mean family. Our results show that optimizing the normalized p-mean objectives produces fair and efficient allocations when the items are goods or chores, divisible or indivisible. For instance, the normalized p-means gives us an infinite class of objectives that produce (i) proportional and Pareto efficient allocations for divisible goods, (ii) approximately proportional and Pareto efficient allocations for divisible chores, (iii) EF1 and Pareto efficient allocations for indivisible goods for two agents, and (iv) EF1 and Pareto efficient allocations for indivisible chores for two agents.
Background: The governments of important tourist source markets imposed additional travel restrictions (the Omicron restrictions) to South Africa (and neighbouring states) as a result of the identification of the Omicron variant of COVID-19 in South Africa. These restrictions interrupted and paused the recovery in international and regional passenger traffic to and from South Africa and its neighbouring states.
Objectives: To determine the impact of Omicron-related air travel restrictions on passenger demand, the number of flights operated (supply of services), average passenger loads carried and salient tourism indicators.
Method: The study identifies the monthly number of passengers and flights operated before and immediately following the imposition and lifting of Omicron-related travel restrictions. The counterfactual, to determine the traffic and tourism recovery would have been had these restrictions not been imposed is made by interpolation.
Results: Significant decreases in the annual number of passengers carried, flights operated and the average loads of passengers were identified within two geographic areas, international and regional traffic, on over-border flights affected by Omicron restrictions and the impact on tourism and employment.
Conclusion: The Omicron restrictions interrupted the recovery trend that started to emerge and caused a decline in passenger and tourism flows, tourism spending and employment.
Contribution: The study determines the impact of the Omicron restrictions on South Africa to prevent rapid government overreaction where the causation of contagion is not objectively demonstrated.
Shipment of goods. Delivery of goods, Transportation and communications
Thalis P.V. Zis, Harilaos N. Psaraftis, Martina Reche-Vilanova
The European Union (EU) transport policy recognizes the importance of the waterborne transport systems as key elements for sustainable growth in Europe. By 2030, 30% of total road freight over 300 km should shift to rail or waterborne transport, and more than 50% by 2050. Thus far, this ambition has failed but there have been several project initiatives within the EU to address these issues. In one of these projects, we consider a new waterborne transport system for Europe that is green, robust, flexible, more automated and autonomous, and able to connect both rural and urban terminals. The purpose of this paper is to describe work and preliminary results from this project. To that effect, and in order to assess any solutions contemplated, a comprehensive set of Key Performance Indicators (KPIs) has been defined, and three specific use cases within Europe are examined and evaluated according to these KPIs. KPIs represent the criteria under which the set of solutions developed are evaluated, and also compared to non-autonomous solutions. They are grouped under economic, environmental and social KPIs. KPIs have been selected after a consultation process involving project partners and external Advisory Group members. Links to EU transport and other regulatory action are also discussed.
Background: Logistics is an integral component for success of an organisation. So correct decision on express logistics procurement plays a critical role in success in delivering right product at right place and right time. Procurement of express logistics service is not very straight forward, instead it requires evaluation of multiple factors.
Objective: The objective of this research is to create a framework of influencing factor on express logistics buying decision.
Method: For the study, researchers has adopted secondary research along with primary research with group of 14 subject matter experts in field of Indian logistics sector. A group of experts comprises of senior managers, consultants and academicians with deep understanding of subject. We have used ISM (Interpretive Structural Modelling) and Cross Impact Matrix Multiplication Applied to Classification (MICMAC) to drive conceptual framework for logistics buying decision.
Results: Framework shows that the decision making in logistics procurement should be highly driven by factors like network reach of Logistics Service Provider (LSP), technology followed by information sharing and strategic partnership. While service quality and cost of logistics remains as frontend factors in logistics procurement decision.
Conclusion: The model output clearly suggests that final objective in buying process of express logistics is driven towards lower cost and improved service level, but it is driven by factors which directly adds value in supply chain like time to market and reverse logistics, technology and reach.
Contribution: The model provides a framework for practitioners, which can enable them in decision making process of logistics procurement.
Shipment of goods. Delivery of goods, Transportation and communications
We study the problem of designing truthful and fair mechanisms when allocating a mixture of divisible and indivisible goods. We first show that there does not exist an EFM (envy-free for mixed goods) and truthful mechanism in general. This impossibility result holds even if there is only one indivisible good and one divisible good and there are only two agents. Thus, we focus on some more restricted settings. Under the setting where agents have binary valuations on indivisible goods and identical valuations on a single divisible good (e.g., money), we design an EFM and truthful mechanism. When agents have binary valuations over both divisible and indivisible goods, we first show there exist EFM and truthful mechanisms when there are only two agents or when there is a single divisible good. On the other hand, we show that the mechanism maximizing Nash welfare cannot ensure EFM and truthfulness simultaneously.
Raphael Piendl, Martin Koning, Francois Combes
et al.
Freight transport demand models are generally based on administrative commodity type segmentation which are usually not tailored to behavioral freight transport demand modelling. Recent literature has explored new approaches to segment freight transport demand, notably based on latent class analysis, with promising results. In particular, empirical evidence from road freight transport modelling in Germany hints at the importance of conditioning and handling constraints as a sound basis for segmentation. However, this literature is currently sparse and based on small samples. Before it can be accepted that conditioning should be integrated in the state-of-the-art doctrine of freight data collection and model specification, more evidence is required. The objective of this article is to contribute to the issue. Using detailed data on shipments transported in France, a model of choice of shipment size with latent classes is estimated. The choice of shipment size is modelled as a process of total logistic cost minimization. Latent class analysis leverages the wide range of variables available in the dataset, to provide five categories of shipments which are both contrasted, internally homogenous, and directly usable to update freight collection protocols. The groups are: "‘standard temperature-controlled food products"’, "‘special transports"’, "‘bulk cargo"’, "‘miscellaneous standard cargo in bags"’, "‘palletised standard cargo"’. This segmentation is highly consistent with the empirical evidence from Germany and also leads to better estimates of shipment size choices than administrative segmentation. As a conclusion, the finding that conditioning and handling information is essential to understanding and modelling freight transport can be regarded as more robust.
Biniam Tekle Teweldebrhan, Praveen Maghelal, Abdulla Galadari
Three-dimensional printing (3DP) will lead to future changes in the structure and supply chain operation of businesses. While prevailing studies focus on qualitative assessments, this study quantitatively estimates 3DP impact on the maritime shipping volume and fleet type by (i) estimating the shipping volume reduction due to the mainstreaming of 3DP, and (ii) identifying the shipping fleet types that might be impacted by the change in the supply chain. The supply chain of the automotive industry in the Middle Eastern (ME) region was considered, and different statistical forecasting tools and linear programming models were applied to predict the demand for vehicles and quantify shipping volume reduction. Using a range of 3D printers (1–10), a 26–39% reduction in ton-miles of shipping by 2040 was predicted. Additionally, a 29–45% possible change in the volume of shipping from car carrier (roll-on/roll-off) fleets to bulk cargo fleet types was also predicted. This study also identified potential 3DP plant locations in the ME region ascertaining the potential loss and benefit that can be gained by the maritime shipping industry. It helps shipping manufacturers, operators, and owners consider future demand in terms of the quantity and types of fleets.
Exposición presentada por el profesor de Derecho Marítimo, don Renato Pezoa Huerta, en el marco del Congreso Anual Argentino del Instituto Iberoamericano de Derecho Marítimo “Transporte Multimodal y Corredor Bioceánico”, organizado por el Instituto Iberoamericano de Derecho Marítimo; Universidad Nacional de La Rioja; Escuela de Abogadas y Abogados del Estado Gobierno de La Rioja. Argentina, 03 de octubre del año 2022.
Background: Air transport connectivity to and within Africa is provided by both African and non-African airlines. These carriers are confronted by both intrinsic and extrinsic challenges, which constrain their ability to provide the level of air transport connectivity demanded to fully enable economic growth for the continent. In addition, since April 2020, the reduction in air connectivity resulting from the coronavirus disease 2019 (COVID-19) pandemic has further constrained the capacity of the air transport industry to meet the passenger and freight demand.
Objective: The primary objective of this study was to identify the challenges faced by the airline industry in sub-Saharan Africa in meeting the air transport demands of expected economic growth, and to rank the identified challenges in terms of their urgency and importance.
Method: Initial data were collected from three sources: (1) a review of the literature, (2) industry reports, and (3) as a further but secondary resource, the key inputs into air connectivity model metrics were used to identify additional possible key result areas.
From these data, the study derived open-ended questions as prompts for face-to-face (not virtual) interviews with chief executives of the airline industry. This enabled triangulation of the initial data for verification, and then prioritisation for its application in a possible subsequent project-based remediation strategy.
Results: This study revealed that lack of route liberalisation, management weaknesses, state protection, lack of competition, connectivity challenges and the need for airline partnerships were the most important challenges faced by the industry. In this study, the identified challenges were ranked by thematic analysis.
Conclusion: The key products of this study include the identification and ranking of the challenges impacting the sub-Saharan African air transport industry.
Shipment of goods. Delivery of goods, Transportation and communications
Maximizing the revenue from selling two or more goods has been shown to require the use of $nonmonotonic$ mechanisms, where a higher-valuation buyer may pay less than a lower-valuation one. Here we show that the restriction to $monotonic$ mechanisms may not just lower the revenue, but may in fact yield only a $negligible$ $fraction$ of the maximal revenue; more precisely, the revenue from monotonic mechanisms is no more than k times the simple revenue obtainable by selling the goods separately, or bundled (where k is the number of goods), whereas the maximal revenue may be arbitrarily larger. We then study the class of monotonic mechanisms and its subclass of allocation-monotonic mechanisms, and obtain useful characterizations and revenue bounds.
O comércio internacional tem como base o transporte marítimo que se encontra em um contexto energético dependente de combustíveis fósseis, mas na transição para um cenário mais sustentável, com energia renovável e combustíveis alternativos como vetores relevantes para a geração de potência em navios. Essa mudança é incentivada por questões econômicas e ambientais, através de estratégias como a implementação de regras para a redução da emissão de gases do efeito estufa pautadas nas reuniões da Organização Marítima Internacional (IMO), que apresentam regulamentações cada vez mais rígidas. Dessa forma, o presente artigo busca mostrar a relevância dos combustíveis alternativos para o transporte marítimo, analisando sua viabilidade de acordo com a movimentação do comércio internacional.