Die Discussion Papers dienen einer möglichst schnellen Verbreitung von neueren Forschungsarbeiten des ZEW. Die Beiträge liegen in alleiniger Verantwortung der Autoren und stellen nicht notwendigerweise die Meinung des ZEW dar.Discussion Papers are intended to make results of ZEW research promptly available to other economists in order to encourage discussion and suggestions for revisions. The authors are solely responsible for the contents which do not necessarily represent the opinion of the ZEW.Download this ZEW Discussion Paper from our ftp server:ftp://ftp.zew.de/pub/zew-docs/dp/dp0506.pdf JEL classification: D61, H21, Q48

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This paper presents a computational evolutionary game model to study and understand fraud dynamics in the consumption tax system. Players are cooperators if they correctly declare their value added tax (VAT), and are defectors otherwise. Each player's payoff is influenced by the amount evaded and the subjective probability of being inspected by tax authorities. Since transactions between companies must be declared by both the buyer and seller, a strategy adopted by one influences the other's payoff. We study the model with a well-mixed population and different scale-free networks. Model parameters were calibrated using real-world data of VAT declarations by businesses registered in the Canary Islands region of Spain. We analyzed several scenarios of audit probabilities for high and low transactions and their prevalence in the population, as well as social rewards and penalties to find the most efficient policy to increase the proportion of cooperators. Two major insights were found. First, increasing the subjective audit probability for low transactions is more efficient than increasing this probability for high transactions. Second, favoring social rewards for cooperators or alternative penalties for defectors can be effective policies, but their success depends on the distribution of the audit probability for low and high transactions.

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This paper analyses the consequences of the upcoming Panama Canal expansion using a liner fleet deployment model (LFDM) applied to the container shipment routing problem. As the canal capacity will be increased in 2016 from 5000 TEUs to 13,000 TEUs vessels, new options will be offered to container liner shippers. Some earlier work has suggested impact on shipping patterns, transshipment and cost structures. We derive optimal results for a MIP implementation of the LFDM adapted to the Panama Canal problem for demand scenarios on different international container traffic routes corresponding to a range of ±17 % of the actual Canal traffic in 2014. Our results show positive effects on total costs from fleet redeployment of larger vessels to the Canal-crossing routes, leading to lowered vessel costs and higher utilization rates. The expansion is also environmentally advantageous since the fleet composition will induce lower bunker fuel consumption and thereby lower CO 2 emissions. However, the total Canal costs are still predicted to be a minor proportion of the cost basis without incentives for additional or alternative Canal capacity.