Walter Kosters

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Walter A. Kosters, a Dutch computer scientist and mathematician, and associate professor of CS at LIACS, the Leiden Institute of Advanced Computer Science at Leiden University. His research interests include neural networks, genetic algorithms, analysis of algorithms, concrete mathematics, NP-completeness, bioinformatics, data mining and artificial intelligence. Along with Hendrik Jan Hoogeboom et al., Walter Kosters works on the computational complexity of Tetris, and maintains the How to Construct Tetris Conﬁgurations site.

=Nonograms= Along with Joost Batenburg, Walter Kosters researches on Nonograms, picture logic puzzles where a pixel grid has to be filled with black and white pixels, based on a description that indicates the lengths of the consecutive black segments for each row and column. In this puzzle type, the numbers are a form of discrete tomography that measures how many unbroken lines of filled-in squares there are in any given row or column. While the Nonograms that can be found in puzzle books can typically be solved by applying a series of highly local reasoning steps regarding single rows and columns, the general Nonogram problem is NP-hard.

=Selected Publications=
 * Ron Breukelaar, Erik D. Demaine, Susan Hohenberger, Hendrik Jan Hoogeboom, Walter Kosters, David Liben-Nowell (2004). Tetris is hard, even to approximate. International Journal of Computational Geometry & Applications, Vol. 14
 * Hendrik Jan Hoogeboom, Walter Kosters (2004). Tetris and Decidability. Information Processing Letters, Vol. 9
 * Hendrik Jan Hoogeboom, Walter Kosters (2004). How to Construct Tetris Conﬁgurations. International Journal of Intelligent Games & Simulation, Vol. 3
 * Hendrik Jan Hoogeboom, Walter Kosters (2005). The Theory of Tetris. Nieuwsbrief van de Nederlandse Vereniging voor Theoretische Informatica, Vol. 9
 * Joost Batenburg, Walter Kosters (2009). Solving Nonograms by combining relaxations. Pattern Recognition, Vol. 42, No. 8
 * Jonathan K. Vis, Walter Kosters, Antonio Terroba (2010). Tennis Patterns: Player, Match and Beyond. BNAIC 2010, pdf
 * Antonio Terroba, Walter Kosters, Jonathan K. Vis (2010). Tactical Analysis Modeling through Data Mining: Pattern Discovery in Racket Sports. KDIR 2010, pdf
 * Jonathan K. Vis, Walter Kosters, Joost Batenburg (2011). Discrete Tomography: A Neural Network Approach. BNAIC 2011 pdf
 * Joost Batenburg, Walter Kosters (2012). Nonograms. LIACS - Leiden Institute of Advanced Computer Science, pdf
 * Joost Batenburg, Walter Kosters (2012). On the Difficulty of Nonograms. ICGA Journal, Vol. 35, No. 4
 * Hendrik Jan Hoogeboom, Walter Kosters, Jan van Rijn, Jonathan K. Vis (2014). Acyclic Constraint Logic and Games. ICGA Journal, Vol. 37, No. 1
 * Jaap van den Herik, Walter Kosters, Aske Plaat, Johanna Hellemons (2015). The 18th Computer Olympiad 2015. ICGA Journal, Vol. 38, No. 4 » 18th Computer Olympiad

=External Links=
 * Walter Kosters
 * Nonogram — Turn your picture into a puzzle
 * The Mathematics Genealogy Project - Walter Kosters
 * How to Construct Tetris Conﬁgurations by Hendrik Jan Hoogeboom and Walter Kosters

=References=

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