A few days ago, an astute visitor* to the CyberJerry Sudoku page successfully responded to the Sudoku Challenge, the first CyberJerry visitor to do so. He found the Sudoku grid pictured which the Analyzer couldn't solve, and told me (in Spanish) how to solve it:

este sudoku lo saque de la pagina https://www.sudoku-online.org de categoria sudoku extremo #717, y su analizar dice que no tiene una solución, sin embargo por metodo analitico encuentro que F6 = 4 debido al 4 de E3 y el 4 de G5, tambien encuentro que I9 = 5 debido al 5 de D8 y al 5 de H4, al colocar estos dos números, ahora si dice que tiene solución única lo anterior esta pasando por que su analizador no está realizando el método más sencillo que es de eliminación directa o único número de la caja, mira la celda I1 = 8 se obtiene por ese método

this sudoku is taken from webpage https://www.sudoku-online.org category extreme sudoku #717, and your analyzer says it has no solution, however by an analytic method I find that F6 = 4 due to the 4 in E3 and the 4 in G5, also I find that I9 = 5 due to the 5 in D8 and the 5 in H4, upon placing these two numbers, now it says that it has one unique solution the above is happening because your analyzer isn't executing the simplest method which is direct elimination or the cell's only number, see how cell I1 = 8 is obtained by this method

*The Challenger is:

Manuel Navarro De La Hoz
birthplace: Galapa del departamento de Atlántico, país Colombia
his YouTube channel: Mr cocogames

I have reviewed the Sudoku in question and have confirmed that my Analyzer does indeed fail to solve it, and that Señor Navarro has described a correct method for solving it. As promised, I am hereby acknowledging the success and superior Sudoku skills of Sr Navarro, and am also working at correcting the problem in the Analyzer.

Congratulations and thanks to Sr Navarro!

2 comments:

Still working on correcting the problem. Here's what I know so far: 1. The Analyzer can indeed solve the Sudoku, but it takes too long to analyze it. A sparse grid (single solution, but with less than 20 filled cells) requires a ton of looping inside the server-side binary executable. 2. The solution seems to be to make the binary faster. Right now it uses simple logic at the machine code level, with much repetitive looping. I ought to make it more complex to reduce the looping repetitions. 3. This will be a significant change to the core logic, which I wrote in assembly over 15 years ago. It will also call for much testing to make sure it still works the same. Maybe I'll write a new blog article when (if) I've done the above.

As noted, this has involved a change to core logic. Am currently testing this new logic in version -->'3.0.test'<--, which you may also test, if you like.

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