2-String Kite
A strong link in a row and one in a column, tied together in a box.
Rule
A row and a column each with only 2 places for d, one end of each in the same box → remove d from cells that see both other ends.
Two strings
Digit 5 has only two places in row 8: r8c8 and r8c3. In column 7 it also has only two: r7c7 and r5c7.
The idea
In a row, d has only two places; in a column, d also has only two places. One end of the row and one end of the column sit in the same box (as two different cells). That is the knot of the kite.
The two knot cells see each other, so they cannot both be d. Whichever of them is not d, the far end of its string is d. So at least one of the two free ends is d, and the cell where their row and column meet loses d.
How to spot it
- For each digit, find a row and a column with only two places, each having one end in the same box.
Common mistakes
- The two knot cells must be different cells.
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Related techniques
References
The examples on this page are generated from random puzzles, not taken from these sources.