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Real-world scheduling is decision making under vague constraints of diierent importance, often using uncertain data, where compromises between antagonistic criteria are allowed. We explain in theory and by detailed examples a new combination of fuzzy set based constraints and repair based heuristics that help to model these scheduling problems. We simplify(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)
The World Wide Web is the largest database of the world - a huge amount of knowledge, information and services primarily intended for human users. Unfortunately, data on the Web requires intelligent interpretation and cannot be easily used by programs. It requires advanced data extraction and integration techniques to automatically process data. Lixto(More)
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)
Due to complexity reasons of realistic scheduling applications, often iterative improvement techniques that perform a kind of local search to improve a given schedule are proposed instead of enumeration techniques that guarantee optimal solutions. In this paper we describe an experimental comparison of four iterative improvement techniques for schedule(More)
We present a scheduling methodology for applications where the generation of schedules is constrained by antagonistic and vague knowledge. Besides temporal and capacity constraints, compatibility constraints between consecutive jobs are managed. We model the vague constraints and uncertain data by fuzzy set theory. The importance of single jobs and and the(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 neighborhood relation. In the move selection process, we make use of the basic prohibition mechanisms of tabu(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)
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)