9×9 · Medium to hard
Greater Than Sudoku
Inequality signs between neighbouring cells tell you which digit is larger — often with no starting digits at all.
About greater than
What greater than sudoku feels like.
Greater than sudoku — also called comparison or inequality sudoku — replaces the starting digits with less-than and greater-than signs between neighbouring cells. Each sign points to the smaller digit, so you deduce the grid entirely from the ordering relationships plus normal sudoku rules. Many versions give no starting digits at all.
Rules
- Standard sudoku rules apply: each digit 1–9 appears once per row, column, and 3×3 box.
- Signs between adjacent cells show which digit is larger; the sign opens toward the larger value.
- Every pair of neighbouring cells with a sign must respect that inequality.
- Often there are no given digits — you solve purely from the inequalities.
History
Comparison sudoku appears in many puzzle magazines under names like Futoshiki (for the pure inequality grid) and greater-than sudoku for the 9×9 boxed version.
- Key rule
- Inequality signs between cells show which neighbour is larger
- Difficulty range
- Medium to hard
- Tips
- Look for chains of signs within a box: a run like a < b < c < d limits each cell's range.
- A cell that is greater than all its neighbours in a box is often an 8 or 9; one smaller than all is often a 1 or 2.
- The longest increasing chain in a unit pins its extremes first.