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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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 Posted: Thu Dec 13, 2007 9:10 am Post subject: recommended: today's nightmare |
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Today's Daily Nightmare once more turned out to be a very satisfying puzzle.
xy-wing and x-wing got me here:
| Code: |
+--------------------------+--------------------------+--------------------------+
| 58 135 18 | 24 359 7 | 89 6 24 |
| 679 37 2 | 46 36 8 | 1 5 49 |
| 4 59 689 | 1 569 25 | 7 3 28 |
+--------------------------+--------------------------+--------------------------+
| 2 6 3 | 8 1 9 | 4 7 5 |
| 1 457 47 | 57 2 3 | 89 89 6 |
| 58 579 789 | 57 4 6 | 3 2 1 |
+--------------------------+--------------------------+--------------------------+
| 3 8 19 | 26 56 4 | 25 19 7 |
| 79 2 5 | 3 78 1 | 6 4 89 |
| 67 147 1467 | 9 78 25 | 25 18 3 |
+--------------------------+--------------------------+--------------------------+
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I see at least two different solution paths now:
A) potential DP (57) r56c24 => r5c2=4 or r6c2=9, both lead to r5c4=5.
B) xy-chain *): (9)r7c3 ... [useless xy-wing 91-18-89 + transport to] ... (9)r5c8 makes r7c8=1
edit: *) xy-chain ? or w-wing ? M-wing ? wingding ?  |
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Earl
Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
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| Posted: Thu Dec 13, 2007 5:59 pm Post subject: Nightmare |
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There is a w-wing 18 apparently elliminating nothing, but if you color the lower pincer 8 to R3C9 that makes R1C7 = 9 and the puzzle is solved.
Earl |
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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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| Posted: Thu Dec 13, 2007 6:41 pm Post subject: |
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I'll add that to the list of powerful chains based on apperently useless wings.
So far, we have:
(9)r7c3 19-18-89-89-89 (9)r5c8 ; r7c8=1 (nataraj's)
(8)r1c3 18-19-19-18-89-49-24-28 (8)r3c9; R1C7 = 9 (Earl's)
If we start with the same useless w-wing but continue up and left we get to r5c7 with the same result
(8)r1c3 18-19-19-18-89-89 (8)r5c7 ; r1c7=9 (Earl's II)
and here's one more, it removes 1 from r7c3. It looks like a normal xy-wing but with an extension cord added in the middle:
(1)r1c3 18-89-89-89-19 (1)r7c8 ; r7c3=9 |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Thu Dec 13, 2007 11:11 pm Post subject: |
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| nataraj wrote: | I'll add that to the list of powerful chains based on apparently useless wings.
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Flightless wings?
Keith |
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TKiel
Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI
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| Posted: Fri Dec 14, 2007 12:32 am Post subject: |
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| Ostrich? |
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Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
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| Posted: Fri Dec 14, 2007 5:55 am Post subject: |
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Some might have noticed I have been intrigued recently with otherwise useless X-Wings involved with overlapping strong links. In this case, I saw the <4> X-Wing in Boxes 2 and 3 with the overlapping <2> strong link in r1. Together with the Box 2 strongly linked <2>s and several related bivalues, I thought: Medusa! I usually don't resort to Medusa so soon. But, this seemed so promising:
| Code: | +--------------+-----------------+--------------+
| 58 135 18 | 2r4g 359r 7 | 8r9g 6 2g4r |
| 679 37 2 | 4r6g 3-6 8 | 1 5 4g9r |
| 4 59 689 | 1 -569g 2g5r | 7 3 2r8g |
+--------------+-----------------+--------------+
| 2 6 3 | 8 1 9 | 4 7 5 |
| 1 457 47 | 57 2 3 | 89 89 6 |
| 58 579 789 | 57 4 6 | 3 2 1 |
+--------------+-----------------+--------------+
| 3 8 19 | 26 56 4 | 25 19 7 |
| 79 2 5 | 3 78 1 | 6 4 89 |
| 67 147 1467 | 9 78 25 | 25 18 3 |
+--------------+-----------------+--------------+ |
Very easily, <5> is eliminated from r3c5. (It contains a green <9> and sees a red <5>.) This makes the <6> in r3c5 red, eliminating <6> from r2c5 and solving the puzzle. |
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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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| Posted: Fri Dec 14, 2007 6:40 am Post subject: |
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That's it! Let's call it ostrich wing (or O-wing for short). Nobody's going to believe this... |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Fri Dec 14, 2007 7:29 am Post subject: |
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| are we "o-wing" you anything for this? |
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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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| Posted: Fri Dec 14, 2007 7:42 am Post subject: |
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it was a collaboration - but "ostrich" was suggested by Tracy, to be sure.
I can think of many more uses for the name. Take those solution methods, for example, that leave me with my mouth open ... :-O oooohhh - wing! |
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