Solving Single-Digit Sudoku Subproblems

  • David Eppstein
Part of the Lecture Notes in Computer Science book series (LNCS, volume 7288)


We show that single-digit “Nishio” subproblems in n×n Sudoku puzzles may be solved in time o(2 n ), faster than previous solutions such as the pattern overlay method. We also show that single-digit deduction in Sudoku is NP-hard.


Truth Assignment Deduction Rule Variable Gadget Clause Gadget Terminal Block 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • David Eppstein
    • 1
  1. 1.Computer Science DepartmentUniversity of CaliforniaIrvineUSA

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