Adjacency Rules
Master the exclusion zone around each queen and learn how diagonal adjacency creates cascading eliminations.
BeginnerUnderstanding the Exclusion Zone
When you place a queen on a cell, every cell directly touching it — horizontally, vertically, and diagonally — becomes unavailable. This means each queen eliminates up to 8 surrounding cells (fewer if the queen is on an edge or corner). This 'exclusion zone' is the key to cascading eliminations.
Cascading Eliminations
The real power of adjacency comes from chain reactions. Placing one queen eliminates cells in surrounding regions. If that elimination leaves a region with only one valid cell, you've found your next queen. That second queen then eliminates more cells, potentially forcing a third placement, and so on. A single well-placed queen can trigger a chain that solves half the puzzle.
Corner and Edge Placement
Queens placed in corners only eliminate 3 adjacent cells, while queens on edges eliminate 5. Interior queens eliminate all 8. This means corner and edge placements are less restrictive — but they also provide less information. When choosing between options, prefer placements that maximize eliminations.
Diagonal Traps
The most commonly forgotten adjacency is the diagonal. Many beginners correctly check rows and columns but forget that diagonal neighbors are also eliminated. When two regions touch only at a diagonal corner, remembering this rule is critical.