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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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 Posted: Fri Mar 06, 2009 7:30 am Post subject: mm 1335 3/6/09 diabolical |
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| Code: |
+-------+-------+-------+
| 1 9 . | . 7 . | . . 2 |
| 8 5 7 | . . . | . . 6 |
| . . . | . 4 8 | . . . |
+-------+-------+-------+
| . . . | . . 5 | . 2 . |
| 2 . . | . . . | . . 5 |
| . 3 . | 2 . . | 1 . . |
+-------+-------+-------+
| . . . | 7 6 . | . . . |
| 9 . . | . . . | . 3 8 |
| 7 . . | . 8 . | . 6 1 |
+-------+-------+-------+
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Play this puzzle online at the Daily Sudoku site
I'd say this is the hardest MM puzzle I seen so far.
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after a couple rounds in the ring.
two steps.
| Code: | .---------------------.---------------------.---------------------.
| 1 9 4 | 356 7 36 | 358 58 2 |
| 8 5 7 | 139 2 139 | 349 149 6 |
| 36 26 236 | 159 4 8 | 59 1579 79 |
:---------------------+---------------------+---------------------:
| 46 7 689 | 468 1 5 | 4689 2 3 |
| 2 1468 1689 | 468 3 467 | 4689 4789 5 |
| 456 3 568 | 2 9 467 | 1 478 47 |
:---------------------+---------------------+---------------------:
| 345 1248 12358 | 7 6 12349 | 2459 459 49 |
| 9 1246 126 | 14 5 124 | 7 3 8 |
| 7 24 235 | 349 8 2349 | 2459 6 1 |
'---------------------'---------------------'---------------------' |
(9)r7c9 = (9)r3c9 - (9=5)r3c7 - (5)r7c9 = (5)r7c8; r7c8 <> 9
that newly opened {4,5} cell in r7c8 can be used
(5=4)r7c8 - (4)r2c8 = (4-3)r2c7 = (3-8)r1c7 = (8)r1c8; r1c8 <> 5
singles follow. |
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Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
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| Posted: Fri Mar 06, 2009 11:02 am Post subject: |
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Norm,
I can't follow this bit: (5)r7c9 = (5)r7c8
You must have meant the grouped link: (5)r13c8=(5)r7c8
Eh?
Congrats on the short solution path! The puzzle did not yield so easily for me. I used several long (but interesting) AICs, including one continuous loop and one strong link discontinuity loop. |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Fri Mar 06, 2009 3:36 pm Post subject: |
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| Asellus wrote: | You must have meant the grouped link: (5)r13c8=(5)r7c8
Eh?
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Or the grouped link (5)r79c7=(5)r7c8.
Yes, congrats on breaking this contrary puzzle. |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Fri Mar 06, 2009 6:23 pm Post subject: |
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| Quote: | You must have meant the grouped link: (5)r13c8=(5)r7c8
Eh? |
| Quote: | | Or the grouped link (5)r79c7=(5)r7c8. |
yes, the grouped link 
(5)r79c7 = (5)r7c8
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I have been keeping track of these "diabolicals" and I am not sure there is precedence for this difficulty, is there?
so I am wondering if there is a move or pattern still in there.
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| Quote: | | one continuous loop and one strong link discontinuity loop |
did one include the 4's ?
if so I looked at the 4's for a long time. |
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Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
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| Posted: Sat Mar 07, 2009 5:47 am Post subject: |
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| Quote: | | did one include the 4's ? |
Neither of those involved <4>s and I'm not now able to recreate the sequence of longish AICs I found last night. However, I can see an interesting AIC "almost loop" involving <4>s:
(4=7)r6c9 - (7=9)r3c9 - (9=5)r6c7 - (5=8)r1c8 - ALS[(8)r6c8=(4)r6c89]; r6c16|r5c78|r4c7<>4
Notice how the grouped <4>s at one end of the AIC include the single <4> at the other end. That's something one might overlook but is entirely valid. We know that one of those two grouped <4>s must be true.
We can now do the same thing with <5>s:
(5=8)r1c8 - ALS[(8)r6c8=(7)r6c89] - (7=6)r6c6 - (6=3)r1c6 - ALS[(3)r1c7=(5)r1c78]; r1c4|r3c78<>5
And, that solves the puzzle. |
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