Flow-based reputation with uncertainty: Evidence-Based Subjective Logic

The concept of reputation is widely used as a measure of trustworthiness based on ratings from members in a community. The adoption of reputation systems, however, relies on their ability to capture the actual trustworthiness of a target. Several reputation models for aggregating trust information have been proposed in the literature. The choice of model has an impact on the reliability of the aggregated trust information as well as on the procedure used to compute reputations. Two prominent models are flow-based reputation (e.g., EigenTrust, PageRank) and Subjective Logic based reputation. Flow-based models provide an automated method to aggregate trust information, but they are not able to express the level of uncertainty in the information. In contrast, Subjective Logic extends probabilistic models with an explicit notion of uncertainty, but the calculation of reputation depends on the structure of the trust network and often requires information to be discarded. These are severe drawbacks. In this work, we observe that the `opinion discounting' operation in Subjective Logic has a number of basic problems. We resolve these problems by providing a new discounting operator that describes the flow of evidence from one party to another. The adoption of our discounting rule results in a consistent Subjective Logic algebra that is entirely based on the handling of evidence. We show that the new algebra enables the construction of an automated reputation assessment procedure for arbitrary trust networks, where the calculation no longer depends on the structure of the network, and does not need to throw away any information. Thus, we obtain the best of both worlds: flow-based reputation and consistent handling of uncertainties

Chaos en orde in de wereldlandbouw

Gebrek aan elasticiteit, solidariteit en autoriteit / door P.C. van den Noort ; Internationale arbeidsverdeling en marktorde / door J. de Hoogh ; Redes 6-12-1979 Wageninge

Bijdrage tot de kennis van den groei van Pseudotsuga taxifolia Britton in Nederland in verband met zijn beteekenis voor den Nederlandschen boschbouw

Development of the green Douglas fir in the Netherlands in different places with different methods of planting was studied by enquiry, personal research and from the literature. The climate and soil types seemed suitable. Game, insects and fungi caused little damage. The stands studied all derived from seed from north-west America but the exact origin was never known. This could explain differences in development and frost resistance. Planting of experimental forests was therefore advised with seed from different latitudes and heights above sea-level.Even on poorer soils the yield was much higher than the best stands of Scots pine, sometimes more than double. Wood production declined over 30 years much more than in Germany through lack of thinnings by too wide a spacing.Further advantages over Scots pine were better decomposition of needles, straighter stems, harder wood as measured by resistance to crushing through a higher porportion of summer wood and early formation of heart wood. A disadvantage was the severe self-pruning. Experience on planting and culture were discussed. Growth in length was strongly influenced by rainfall in the same year.</p

Pachtprijsbeheersing en landbouwprijsbeleid in Nederland

Since 1938 there has been a policy of rent arbitration in the Netherlands. Rent arbitration appeared to be necessary through the price policy of agricultural products. The purpose was to divide agricultural income fairly between farmers and the landowners. The author argued that rent arbitration should also be treated as an instrument and not only a consequence of agricultural price policy. By giving guaranteed prices to the farmers the government influenced on the land rent, but the land rent resulting from arbitration should also influence the guaranteed prices for agricultural products.The thesis provides a detailed description and analysis of the methods of rent arbitration, and some suggestions for improving the methods. Rent arbitration had had an important influence: before rent arbitration came into force, total net rent was about 25 % of agricultural income, whereas it is now only 5 %. It was argued, however, that other influences were also at work; without rent arbitration that percentage could have decreased also.<p/