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Jigsaw 42: Ultra hard tag?

 
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sudokuEd
Grandmaster
Grandmaster


Joined: 19 Jun 2006
Posts: 257
Location: Sydney Australia

PostPosted: Sun Apr 22, 2007 7:40 am    Post subject: Jigsaw 42: Ultra hard tag? Reply with quote

Anyone else want to work on Jigwaw 42 this week? If we get stuck for 24 hours someone gets a hint from SumoCue and runs with it.

Starting from basic moves gets to here:
Code:
.--------.--------.--------.--------.--------.--------.--------.--------.--------.
| 3      | 6      | 148    | 124789 | 12479  | 5      | 12489  | 124789 | 1278   |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 27     | 279    | 148    | 279    | 14     | 6      | 3      | 18     | 5      |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 9      | 478    | 148    | 5      | 6      | 12478  | 128    | 12378  | 12378  |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 1      | 5      | 2      | 3      | 8      | 9      | 7      | 6      | 4      |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 5      | 478    | 3      | 478    | 1247   | 1248   | 6      | 1248   | 9      |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 278    | 1237   | 6      | 1247   | 5      | 1247   | 12489  | 123489 | 1238   |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 278    | 1237   | 9      | 6      | 127    | 12478  | 1248   | 5      | 1238   |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 4      | 127    | 5      | 1289   | 129    | 3      | 1289   | 12789  | 6      |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 6      | 2489   | 7      | 12489  | 3      | 1248   | 5      | 1289   | 128    |
'--------'--------'--------'--------'--------'--------'--------'--------'--------'


1. LoL c789 -> no 9 r1c78

2. LoL r12 -> no 4 r3c36
2a. r3c2 = 4 (hidden(h) single (s) r3

3. r5c24 = {78}:7,8 locked for r5

4. X-wing on 8's in n6 and 7. 8 locked for r67

5. no 4 in r5c6 because of 4's in r9
5a. 4 in r9c4 -> 4 in n5 in r5c5 or rrc6 -> no 4 r5c6
5b. 4 in r9c6 -> no 4 r5c6

6. LoL c789 -> no 8 r1c78

7. LoLc123 -> 7 locked for c4 in r25c4

8. 2 7's in n5 -> no 7 r7c6
8a. r8c8 = 7 (hs n9)

9. naked triple 1/2/4 n2:locked for n2
9a. 2 locked for r1
9b. -> 2 locked for c6 in r57c6 (LoLc789)
9c. -> Common Peer Elimination (CPE) -> no 2 r7c9

10. no 8 r3c7 because of weak links on 8 in c6 and r8

11. naked triple 1/2/4 in c7: locked for c7
Can't find any more:
Code:
.--------.--------.--------.--------.--------.--------.--------.--------.--------.
| 3      | 6      | 148    | 89     | 79     | 5      | 124    | 124    | 178    |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 27     | 279    | 148    | 279    | 14     | 6      | 3      | 18     | 5      |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 9      | 4      | 18     | 5      | 6      | 78     | 12     | 1238   | 12378  |

:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 1      | 5      | 2      | 3      | 8      | 9      | 7      | 6      | 4      |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 5      | 78     | 3      | 78     | 124    | 12     | 6      | 124    | 9      |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 278    | 1237   | 6      | 124    | 5      | 147    | 89     | 123489 | 1238   |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 278    | 1237   | 9      | 6      | 127    | 124    | 124    | 5      | 138    |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 4      | 12     | 5      | 1289   | 129    | 3      | 89     | 7      | 6      |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 6      | 289    | 7      | 12489  | 3      | 148    | 5      | 1289   | 128    |
'--------'--------'--------'--------'--------'--------'--------'--------'--------'
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Para
Yokozuna
Yokozuna


Joined: 08 Nov 2006
Posts: 384
Location: The Netherlands

PostPosted: Sun Apr 22, 2007 11:36 am    Post subject: Reply with quote

Ok, this move comes from your givens form. (would also work for vanilla sudoku)

12. Y-wing: R8C4: no 8 <<-- R1C4 and R8C7 can together see all 9's in C5. So they can't both be 9. Any cells that see both cells can't contain an 8.

13. R8C7 = 8(hidden single); R6C7 = 9

14. R9C8 = 9(hidden single)

Code:
.--------.--------.--------.--------.--------.--------.--------.--------.--------.
| 3      | 6      | 148    | 89     | 79     | 5      | 124    | 124    | 178    |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 27     | 279    | 148    | 279    | 14     | 6      | 3      | 18     | 5      |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 9      | 4      | 18     | 5      | 6      | 78     | 12     | 1238   | 12378  |

:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 1      | 5      | 2      | 3      | 8      | 9      | 7      | 6      | 4      |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 5      | 78     | 3      | 78     | 124    | 12     | 6      | 124    | 9      |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 278    | 1237   | 6      | 124    | 5      | 147    | 9      | 12348  | 1238   |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 278    | 1237   | 9      | 6      | 127    | 124    | 124    | 5      | 138    |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 4      | 12     | 5      | 129    | 129    | 3      | 8      | 7      | 6      |
:--------+--------+--------+--------+--------+--------+--------+--------+--------:
| 6      | 28     | 7      | 1248   | 3      | 148    | 5      | 9      | 12     |
'--------'--------'--------'--------'--------'--------'--------'--------'--------'


There might be more now but this was just in a quick view.

greetings

Para
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Para
Yokozuna
Yokozuna


Joined: 08 Nov 2006
Posts: 384
Location: The Netherlands

PostPosted: Sun Apr 22, 2007 9:25 pm    Post subject: Reply with quote

I said there was more.

15. R2C2 = 9 (Hidden single)

16. Y-wing: R9C2: no 2 <<-- R8C2 + R9C9 together see all 1's in N8. So all cells that see both cells can't contain a 2.

And the rest is naked and hidden singles.

Para
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