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iSGTW Link of the week - How low can a Sudoku go?

Link of the week - How low can a Sudoku go?


What is the minimum number of clues required to solve a Sudoku? The BOINC-powered Sudoku project is keen to find out.
Image courtesy of the Sudoku project

There are two ways to solve a Sudoku: by hand, or by writing a computer program to do it for you.

For "ordinary" Sudoku-where you begin with 25 to 30 "clue" numbers-this is a relatively simple proposition. But what happens when you start with half as many clues?

Can you still solve a Sudoku which begins with only ten clues? What about five clues? How low can a Sudoku go while still ensuring it has only one unique solution?

Running the numbers

So far, all known minimal Sudokus with a unique solution begin with 17 "clue" numbers. Further, any puzzles with fewer than eight clues have resulted in at least two different solutions. Thus, minimal Sudokus are thought to require 8-17 numbers.

A new BOINC-powered distributed computing project-Sudoku-is determined to close this gap, aiming to discover the smallest possible start configuration required to solve a Sudoku that has only one, unique solution.

Those involved in the project say initial evaluations have reduced the range to 11-17 initial clues; the next step is to use volunteer computing to increase this lower number, until one user either finds a new minimal example, or it can be shown that no such examples exist for up to 16 givens.

You can participate by downloading and running the BOINC program on your computer.

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