Welfare-Enhancing Collusion in the Presence of a Competitive Fringe

Following the structure of many commodity markets, we consider a few large firms and a competitive fringe of many small suppliers choosing quantities in an infinite-horizon setting subject to demand shocks. We show that a collusive agreement among the large firms may not only bring an output contraction but also an output expansion (relative to the noncollusive output level). The latter occurs during booms, when the fringe’s market share is more important, and is due to the strategic substitutability of quantities (we will never observe an output-expanding collusion in a price-setting game). In addition and depending on the fringe’s market share the time at which maximal collusion is most difficult to sustain can be either at booms or recessions.

Un lingote de plomo plano-convexo hallado en la Ribera de Cabanes (Castellón)

Se presenta el estudio de un lingote de plomo de forma plano-convexa localizado hace años en un campo de cultivo de la Ribera de Cabanes (Castellón). La pieza fue cedida recientemente para efectuar su estudio morfo-tipológico, análisis de composición y de isótopos cuyos resultados indican una probable cronología protohistórica (época Ibérica) y un origen en las minas de Cartagena. Se efectúa también una breve contextualización del entorno del hallazgo, caracterizada por un poblamiento importante con diversos asentamientos del Hierro Antiguo e Ibéricos, entre los que se ha identificado indicios de circulación y producción metalúrgica.We present the study of a flat-convex lead ingot finded years ago in the Ribera de Cabanes (Castellón, Spain). The results of its morpho-typological study, analysis of composition and isotopes indicate a probable protohistoric chronology (Iberian Age) and an origin in the mines of Cartagena. We present also a brief contextualization of the archaeological environment, with some Iron Age settlements among which has been identified some signs of circulation and metallurgical production

Welfare-enhancing collusion in the presence of a competitive fringe

Following the structure of many commodity markets, we consider a reduced number of large firms and a competitive fringe of many small suppliers choosing quantities in an infinitehorizon setting subject to demand shocks. We show that a collusive agreement among the large firms may not only bring an output contraction but also an output expansion (relative to the non-collusive output level). The latter occurs during booms, when the fringe's market share is more important, and is due to the strategic substitutability of quantities (we will never observe an output expanding collusion in a price setting game). In addition and depending on the fringe's market share the time at which collusion is most difficult to sustain can be either at booms or recessions

Supporting personalization in a web-based course through the definition of role-based access policies

Role-based access policies model the users domain by means of complex structures where roles, which represent jobs or responsibilities assumed by users, are specialized into more concrete subroles which inherit properties and authorizations from their parents. Such an approach can be applied within the context of educational applications, where different roles are easily identified each of which has different views of the same information items and different capabilities to modify them. Moreover, even though this approach, has only been oriented towards modeling security requirements, it can be extended to support personalized access to the information. In this paper, we describe how to combine the basic principles of RBAC policies and adaptation with a view of providing personalized access to the different types of users of a web-based course. Moreover, we also present Courba, a platform to generate personalized web-based courses using XML to support the definition of access policies.Role-based access policies model the users domain by means of complex structures where roles, which represent jobs or responsibilities assumed by users, are specialized into more concrete subroles which inherit properties and authorizations from their parents. Such an approach can be applied within the context of educational applications, where different roles are easily identified each of which has different views of the same information items and different capabilities to modify them. Moreover, even though this approach, has only been oriented towards modeling security requirements, it can be extended to support personalized access to the information. In this paper, we describe how to combine the basic principles of RBAC policies and adaptation with a view of providing personalized access to the different types of users of a web-based course. Moreover, we also present Courba, a platform to generate personalized web-based courses using XML to support the definition of access policies

Cuantificación y representación gráfica de los materiales ceramicos mayas: una propuesta metodológica.

Sin resume

Supporting personalization in a web-based course through the definition of role-based access policies

Role-based access policies model the users domain by means of complex structures where roles, which represent jobs or responsibilities assumed by users, are specialized into more concrete subroles which inherit properties and authorizations from their parents. Such an approach can be applied within the context of educational applications, where different roles are easily identified each of which has different views of the same information items and different capabilities to modify them. Moreover, even though this approach, has only been oriented towards modeling security requirements, it can be extended to support personalized access to the information. In this paper, we describe how to combine the basic principles of RBAC policies and adaptation with a view of providing personalized access to the different types of users of a web-based course. Moreover, we also present Courba, a platform to generate personalized web-based courses using XML to support the definition of access policies.Role-based access policies model the users domain by means of complex structures where roles, which represent jobs or responsibilities assumed by users, are specialized into more concrete subroles which inherit properties and authorizations from their parents. Such an approach can be applied within the context of educational applications, where different roles are easily identified each of which has different views of the same information items and different capabilities to modify them. Moreover, even though this approach, has only been oriented towards modeling security requirements, it can be extended to support personalized access to the information. In this paper, we describe how to combine the basic principles of RBAC policies and adaptation with a view of providing personalized access to the different types of users of a web-based course. Moreover, we also present Courba, a platform to generate personalized web-based courses using XML to support the definition of access policies