There are puzzles which do have a unique solution but have not (yet?) yielded to logic that does not backtrack. For example
- Code: Select all
*2*|***|5** 721|436|598
**9|7**|*** 639|758|241
***|**1|*3* 548|291|736
---+---+--- ---+---+---
4**|*7*|**9 412|375|689
3**|*2*|**7 => 396|824|157
8**|*6*|**4 857|169|324
---+---+--- ---+---+---
*6*|9**|*** 163|982|475
***|**3|8** 974|513|862
**5|***|*1* 285|647|913
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Pete Forman