This blog deals with grid-based puzzles and the various types of logic and ideas used to solve them. It also contains notices, information and results about various puzzle and sudoku championships across the globe.
Place numbers in the grid such that each row, column and 3x3 box contain the numbers 1 to 9. All adjacent cells with two digits summing to 5 are marked by V, while those summing to 10 are marked by X. The cells edges which do not contain an X or a V cannot have digits summing to 5 or 10.