Please take a look here
http://www.thestar.com/article/222620
Mada
We all know here, that it is most unprobable, that there is a 16 clue. But i bet those people would not even be capable to prove, that a 12 clue is not possible.But the professors are still stumped by some Sudoku characteristics, like the absolute minimum number of initial numbers that will produce a puzzle with only one solution. It could be 16 or even smaller, says Murty, and computers simply aren't up to the job of running the necessary calculation.
ravel wrote:We all know here, that it is most unprobable, that there is a 16 clue. But I bet those people would not even be capable to prove, that a 12 clue is not possible.
Would say 77 ....... and puzzles with as many as 29 starting entries can still have more than one correct solution.
There are about 10^26 different and valid (unique) and minimal Sudoku games. 5.47..*10^9 is the number of non equivalent sudoku grids (solutions) - and it was not found with graph theory methods (rather combinational theory).And there are more than enough squares to feed the obsession: the researchers say there are 5,472,730,538 different and valid Sudoku games.
ravel wrote:But i bet those people would not even be capable to prove, that a 12 clue is not possible.