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Greater than sudoku
This is the penultimate puzzle in our series of sudoku variations. It was kindly provided by Brainfreeze puzzles, a puzzle making company run by the mathematician Laura Taalman and the software developer Philip Riley, whose book Color Sudoku is published by Sterling Publishing.
Each of the numbers 1 to 9 must appear exactly once in each row, column, and block. In addition, adjacent cells must obey any "greater than" (>) or "less than" (<) symbol that appears on their dividing line. Note that this puzzle has no starting clues given; the greater than symbols are enough to determine a unique solution without any initial conditions at all! As an aid in solving, some cells have been shaded. Cells with a lower value than all their neighbours are blue; cells with a higher value than all their neighbours are red. Happy puzzling!
![](/issue44/puzzle/sudoku_44.png)
If you are stumped by last issue's puzzle, here is the solution.
For some challenging mathematical puzzles, see the NRICH puzzles from this month or last month.