- Code: Select all
*-----------------------------------------------------------------------*
| 5 18 9 | 4 6 3 | 128 7 128 |
| 6 27 27 | 19 8 19 | 4 5 3 |
| 1-8 3 4 | 7 5 2 | 189 a1689 1689 |
|-----------------------+-----------------------+-----------------------|
| 7 4 5 | 3 19 6 | 189 2 189 |
| 9 6 1 | 2 4 8 | 7 3 5 |
| 238 28 238 | 19 7 5 | 6 19 4 |
|-----------------------+-----------------------+-----------------------|
|d1238 9 6 | 5 13 7 |c1238 4 c128 |
| 4 1258 238 | 6 139 19 | 12358 b18 7 |
| 13 157 37 | 8 2 4 | 1359 169 169 |
*-----------------------------------------------------------------------*
There is a two stringed kite in the cells I've marked abcd.
If r3c8 (Cell a) is not 8 then r8c8 (Cell b) must be 8 (only 2 8's in Column 8). So both r7c79 (Cells c) can't be 8, so r7c1 (Cell d) must be 8 (Only 3 8's in Row 7).
You can reverse the argument and assume that Cell d is not 8 and conclude that Cell a must be 8. So at least one of Cells a and d must be 8. They might both be 8 but they can't both be not 8.
Since r3c1 sees both of Cells a and d it can't be 8, so it is 1. The puzzle solves easily after that.
Here is a link to a site that discusses two stringed kites (and a lot else as well)
http://hodoku.sourceforge.net/en/tech_sdp.php#t2skLeren