we turn coffee into puzzles


Greater Than Sudoku

Each of the numbers 1-9 must each 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 neighbors are blue; cells with a higher value than all their neighbors are red.


Appeared in The Big Notebook, a publication of the Mathematical Association of America's Special Interest Group on Mathematics in Business, Industry, and Government, Volume 3, Number 1, April 2007.