2-String Kite
A row strong link and a column strong link whose inner endpoints share a 3×3 box. The far endpoints' intersection cell loses the digit.
Advanced sudoku technique
What it is
A 2-String Kite is another Turbot Fish member, sibling to Skyscraper. The pattern needs three pieces: - A row where digit X has exactly two candidate cells (the row 'string'). - A column where digit X has exactly two candidate cells (the column 'string'). - The inner endpoint of the row string and the inner endpoint of the column string share a 3×3 box. Inside that shared box, only one of the two inner endpoints can hold X. Whichever doesn't, the OUTER endpoint on the same line is forced to hold X. So the two outer endpoints are connected: at least one of them holds X. Therefore the cell at the intersection of the row outer endpoint's column and the column outer endpoint's row — the cell that 'sees' both outers — drops X.
When to use it
On expert puzzles after X-Wing, Swordfish, and Skyscraper are exhausted.
Worked example
Digit 4 in row 3 has strong link R3C2↔R3C5 (only those two cells in row 3 hold 4). Digit 4 in column 7 has strong link R3C7↔R8C7. R3C5 (inner row endpoint) and R3C7 (inner column endpoint) both sit in box 2. So the outer endpoints R3C2 and R8C7 are kite-linked. The cell at column 2 × row 8 — R8C2 — sees both outers and drops 4.
Try it
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