Two-String Kite Sudoku Strategy Explained
A Two-String Kite combines one row strong link and one column strong link for the same digit. One endpoint from each link lies in the same 3×3 box. The other two endpoints become the outer tips. At least one outer tip must contain the digit, so a cell that sees both tips cannot keep it.
One row string, one column string, and a shared box transfer the truth to the two outer tips.
What is a Two-String Kite?
For candidate X, choose a row with exactly two X positions and a column with exactly two X positions. One row endpoint and one column endpoint must share a box but be different cells. The remaining row and column endpoints are the outer tips. A candidate X at the intersection peer of both tips can be eliminated.
How to verify a Two-String Kite
- Choose a row strong link. The target digit must appear exactly twice in that row.
- Choose a column strong link. The same digit must appear exactly twice in that column.
- Join the links through one box. One endpoint from each link must occupy the same 3×3 box.
- Use the outer tips. Remove the digit from a cell that sees both remaining endpoints.
Example: a kite on candidate 5
Row 4 has 5 only at c2 and c8. Column 6 has 5 only at r2 and r5. Cells r4c8 and r5c6 share the middle-right box, leaving r4c2 and r2c6 as outer tips.
- Confirm both strings. The selected row and column each contain exactly two candidates for 5.
- Confirm the box bridge. One endpoint from each string sees the other inside the same box.
- Eliminate from the common peer. A cell that sees both r4c2 and r2c6 cannot contain 5.
Common Two-String Kite mistakes
Using a weak link
Both the row and column strings must be strong links with exactly two candidates.
Skipping the box bridge
The inner endpoints must share one 3×3 box.
Targeting the wrong intersection
The eliminated cell must see both outer tips, not both inner endpoints.
Two-String Kite practice checklist
- Map row and column conjugate pairs for one digit.
- Look for one endpoint from each pair sharing a box.
- Trace the two outer tips to their common peer before deleting.
The pattern is easier to find from strong links than from its silhouette. Pair one row link with one column link, verify the shared box, and let the two outer tips define the elimination.
Two-String Kite FAQ
Why is it called a Two-String Kite?
The row and column strong links form two strings, while their box connection and outer endpoints resemble a kite structure.
Must both links use the same digit?
Yes. Every endpoint and the elimination concern one candidate digit.
Can the outer tips share a box?
They may, but the key requirement is that the elimination target sees both outer tips.
