In a paper arXived on Friday, Roberto Fontana relates the generation of Sudoku grids to the one of Latin squares (which is unsurprising) and to maximum cliques of a graph (more surprising). The generation of a random Latin square proceeds in three steps: generate a random Latin square L with identity permutation matrix on symbol […]
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random sudokus
June 4, 2013tak1ng sudoku ser1ously
March 14, 2013“There is something deeply satisfying in encountering opacity.” (p.9) I think it was last summer at the Australasian Statistics conference in Adelaide that I saw this book by Jason Rosenhouse and Laura Taalman, Taking Sudoku seriously: The math behind the World’s most popular pencil puzzle. (Or was it in Kyoto at the ISBA meeting?!) In […]
simulated annealing for Sudokus [2]
March 17, 2012On Tuesday, Eric Chi and Kenneth Lange arXived a paper on a comparison of numerical techniques for solving sudokus. (The very Kenneth Lange who wrote this fantastic book on numerical analysis.) One of these techniques is the simulated annealing approach I had played with a long while ago. They seem to use the same penalisation […]
Sudokus with minimum number of clues
January 9, 2012Yesterday, I spotted on Mathblogging.org a Spanish post on the minimal number of clues to solve a Sudoku in a unique way. The original paper was posted on arXiv on January 1, in the Data structure and algorithms category. The authors, Gary McGuire, Bastian Tugemann, and Gilles Civario from University College Dublin, have shown by […]
Surprising sudoku
March 1, 2011Yesterday, I was finishing a sudoku grid in the metro and I ended up with four entries a,b,b,a that could be entered in two symmetric ways! Nothing mathematically surprising. However, this never happened to me before and, while it is obviously a possibility, I had not realised that sudoku creators could choose this option… This […]
