Lessons from Modeling Sudoku in Excel

In a previous paper, Chlond [Chlond, M. J. 2005. Classroom exercises in IP modeling: Sudoku and the log pile. INFORMS Trans. Ed.5(2), http://ite.pubs.informs.org/Vol5No2/Chlond/ (last accessed on May 11, 2006)] presented the formulation of Sudoku as an integer program. Chlond claims that a spreadsheet formulation is not straightforward but we present a simple Excel formulation. In light of the current use of Excel in the classroom it can be highly instructive to formulate the problem using Excel. In addition, the formulation of this relatively simple model enables instructors to introduce students to the capability of programming Solver using VBA. In a follow-on paper (Rasmussen and Weiss [Rasmussen, R. A., H. J. Weiss. 2007. Advanced lessons on the craft of optimization modeling based on modeling sudoku in excel. INFORMS Trans. Ed. To appear]), we demonstrate advanced lessons that can be learned from using Premium Solver's powerful features to model Sudoku.