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We submitted two kinds of strategies to the iterated prisoner's dilemma (IPD) competitions organized by Graham Kendall, Paul Darwen and Xin Yao in 2004 and 2005 1. Our strategies performed exceedingly well in both years. One type is an intelligent and optimistic enhanced version of the well known TitForTat strategy which we named OmegaTitForTat. It(More)
Tagging is a promising method for organising and refinding information. However, studies comparing tagging mechanisms to organising information in folder hierarchies are relatively scarce. A study with the software framework tagstore shows that tagging does not necessarily mean slower filing performance. For experienced users, tagging required less time,(More)
Generating high-quality schedules for a rotating workforce is a critical task in all settings where a certain staffing level must be guaranteed beyond the capacity of single employees, such as for instance in industrial plants, hospitals, or airline companies. Results from ergonomics [2] indicate that rotating workforce schedules have a profound impact on(More)
Network design problems, such as generalizations of the Steiner Tree Problem, can be cast as edge-cost-flow problems. An edge-cost flow problem is a min-cost flow problem in which the cost of the flow equals the sum of the costs of the edges carrying positive flow.We prove a hardness result for the Minimum Edge Cost Flow Problem (MECF). Using the one-round(More)
Designing shifts is one of the important stages in the general workforce scheduling process. In this paper we consider solving the shift design problem by using local search methods. First we propose a set of move types that give rise to a composite neighbourhood relation. In the move selection process, we make use of the basic prohibition mechanisms of(More)
The relevance of enabling mobile access to business enterprise information systems for experts working in the field has grown significantly in the last years due to the increasing availability of smartphones; the shipment of smartphones exceeded that of personal computers in 2011. However, the screen sizes and display resolutions of different devices vary(More)
The min-SHIFT DESIGN problem (ÅËË) is an important scheduling problem that needs to be solved in many industrial contexts. The issue is to find a minimum number of shifts and the number of employees to be assigned to these shifts in order to minimize the deviation from workforce requirements. Our research considers both theoretical and practical aspects of(More)
The typical process of planning and scheduling a rotating workforce in an organization consists in designing shifts and then assigning employees to these shifts and to periods of rest (days-off). Successfully solving these problems has high practical relevance: Results from ergonomics indicate that shift schedules have a profound impact on the health and(More)