2024 Sudoku GP1 round - XV Puzzle (deep dive)

Dear competitors,

there has been more questions and objections regarding to the XV Sudoku in Sudoku GP1 and the fact that there weren't any marked signs V and X.

Rules of XV Sudoku in Sudoku GP1:
Apply classic sudoku rules. Adjacent cells containing digits summing to 5 are marked with a "V"; adjacent cells containing digits summing to 10 are marked with an "X". Adjacent cells with no marking must not contain digits summing to 5 or 10.

I have highlighted the last sentence because this one was crucial to be able to succeed with the XV Sudoku solution. There weren't any V or X signs. But there was applied the rule for the XV distribution. Usually it is called by players as a negative rule. So you need to apply it to be able to solve the puzzle.

Using negative conditions is a technique to speed up the solution but be careful if the rules of the puzzle allows it! When all occurrences are mentioned in the rules it is applicable. Usually this is possible by Consecutive Sudoku, XV Sudoku and many others.

Karel Tesař
WPF Sudoku GP 2024
Site Administrator