Initial hint of Sudoku The minimum number is "17", if it can not be solved below, the mathematician concludes

ByMiss_Bathory

A popular numerical puzzle "Sudoku" not only in Japan but also abroad. The number of hints to be placed at the beginning is often 20 to 30, and at the minimum, 17 things are confirmed, but there was no conclusion as to which line is established as a problem However, Irish mathematicians have concluded that "I can not solve if the hint is 16 or less."

Mathematician claims breakthrough in Sudoku puzzle: Nature News & amp; Comment


Gary McGuire's Minimum Sudoku Page, Sudoku Checker

University College / DublinMathematician Gary McGuire proved that in Sudoku anything less than 16 hints can not have a solution. The conclusion that McCuire's proof is probably correct as a result of discussion among mathematicians has been issued.

"Sudoku" stands for "number is limited to single". This name was made by puzzle production company Nikoli, it became a registered trademark of Nikoli, and it is familiar with "Sudoku" not only in Japan but also abroad. It is also called number Place (Nample).


ByWil C. Fry

Sudoku is the most popular thing, "In the lattice that is divided into 9x9," the same number must not appear in vertical and horizontal "" When the same figure appears in 3 x 3 small lattice In accordance with the rule "Do not become", it is to insert numbers from 1 to 9. Several numbers are initially arranged as hints from the beginning, and about 25 numbers are entered for orthodox things, and as the difficulty generally increases, the number of initial placement numbers decreases.


ByJafin 89

Among the puzzles that have appeared so far, there were 17 hints that were the smallest, and it was told that not more than 16 things could be made. There is a method of solving Sudoku with 16 hints to prove this, but it takes a considerable amount of time to calculate with a computer. Therefore, McGuire simplified the problem using "hitting-set algorithm". In 2 years I spent 7 million CPU time challenging and I got to the answer.

McGuire expects that this solution will be useful not only for Sudoku, but also for analysis of gene sequence elucidation technology, analysis by cellular networks and other researchers.

By the way, Mr. McGuire himself likes crossword puzzles more than Sudoku.