Redundant Sudoku rules. Issue 3 (May 2014)

• Record Type: Journal Article
• Authors: DEMOEN, BART; GARCIA DE LA BANDA, MARIA
• Is Part Of: Theory and practice of logic programming. Volume 14:Issue 3(2014)
• Page Start: 363
• Page End: 377
• Publication Date: 2014-05
• Subjects: Logic programming -- Periodicals; Artificial intelligence -- Computer programs -- Periodicals; Constraint programming (Computer science) -- Periodicals; 005.115
• DOI: 10.1017/S1471068412000361
• Languages: English
• ISSNs: 1471-0684

Abstract

<abstract abstract-type="normal"> <title>Abstract</title> <p>The rules of Sudoku are often specified using 27 <monospace>all_different</monospace> constraints, referred to as the <italic>big</italic> constraints. Using graphical proofs and exploratory logic programming, the following main and new result is obtained: Many subsets of six of these big constraints are redundant (i.e., they are entailed by the remaining 21 constraints), and six is maximal (i.e., removing more than six constraints is not possible while maintaining equivalence). The corresponding result for binary inequality constraints, referred to as the <italic>small</italic> constraints, is stated as a conjecture.</p> </abstract>