Monopolistic Group Design with Peer Effects

In a range of settings, private firms manage peer effects by sorting agents into different groups, be they schools, neighbourhoods or teams. This paper considers such a firm, which controls group entry by setting a series of anonymous prices. We show that private provision systematically leads to two distortions relative to the efficient solution: first, agents are segregated too finely; second, too many agents are excluded from all groups. We demonstrate that these distortions are a consequence of anonymous pricing and do not depend upon the nature of the peer effects. This general approach also allows us to assess the way the `returns to scale' of peer technology and the cost of group formation affect the optimal group structure.mechanism design, peer effects, public goods

Durable-Goods Monopoly with Varying Cohorts

mechanism design, pricing, optimal stopping

Hypertext in the Semantic Web

The Semantic Web extends the current state of the Web with well-defined meaning. We advocate the use of ontological hypertext as an application of the Semantic Web to provide a principled and structured approach to navigating the resources on the Web. This paper demonstrates how we have applied this concept to two real-world scenarios

Hypertext in the Semantic Web

The Semantic Web extends the current state of the Web with well-defined meaning. We advocate the use of ontological hypertext as an application of the Semantic Web to provide a principled and structured approach to navigating the resources on the Web. This paper demonstrates how we have applied this concept to two real-world scenarios

Linking with Meaning: Ontological Hypertext for Scholars

The links in ontological hypermedia are defined according to the relationships between real-world objects. An ontology that models the significant objects in a scholar’s world can be used toward producing a consistently interlinked research literature. Currently the papers that are available online are mainly divided between subject- and publisher-specific archives, with little or no interoperability. This paper addresses the issue of ontological interlinking, presenting two experimental systems whose hypertext links embody ontologies based on the activities of researchers and scholars

A Risk Assessment Architecture for Enhanced Engine Operation

On very rare occasions, in-flight emergencies have occurred that required the pilot to utilize the aircraft's capabilities to the fullest extent possible, sometimes using actuators in ways for which they were not intended. For instance, when flight control has been lost due to damage to the hydraulic systems, pilots have had to use engine thrust to maneuver the plane to the ground and in for a landing. To assist the pilot in these situations, research is being performed to enhance the engine operation by making it more responsive or able to generate more thrust. Enabled by modification of the propulsion control, enhanced engine operation can increase the probability of a safe landing during an inflight emergency. However, enhanced engine operation introduces risk as the nominal control limits, such as those on shaft speed, temperature, and acceleration, are exceeded. Therefore, an on-line tool for quantifying this risk must be developed to ensure that the use of an enhanced control mode does not actually increase the overall danger to the aircraft. This paper describes an architecture for the implementation of this tool. It describes the type of data and algorithms required and the information flow, and how the risk based on engine component lifing and operability for enhanced operation is determined

Genetic Affinities of Oceanic Populations based on RFLP and haplotype analysis of genetic loci on three chromosomes

Restriction fragment length polymorphisms at the renin and factor 13B loci located at chromosome lq32-lq42 were studied in 14 ethnic groups in the west Pacific region. The allele frequencies were combined with previously described 13-globin and albuminvitamin D binding protein haplotype frequencies and used to assess genetic affinities among eight major ethnic-geographic groups in this region. These population groups divide into two clusters with Australian Aborigines, Island Melanesians, and Highland Melanesians forming one cluster and east Asians, Southeast Asians, Micronesians, and Polynesians forming the other. The results indicate that Micronesians and Polynesians are derived from populations in Southeast Asia and that they originated independently of the Melanesian populations

The Semantics of Semantic Annotation

Semantic metadata will play a significant role in the provision of the Semantic Web. Agents will need metadata that describes the content of resources in order to perform operations, such as retrieval, over those resources. In addition, if rich semantic metadata is supplied, those agents can then employ reasoning over the metadata, enhancing their processing power. Key to this approach is the provision of annotations, both through automatic and human means. The semantics of these annotations, however, in terms of the mechanisms through which they are interpreted and presented to the user, are sometimes unclear. In this paper, we identify a number of candidate interpretations of annotation, and discuss the impact these interpretations may have on Semantic Web applications