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Steve R
Joined: 24 Oct 2005
Posts: 289
Location: Birmingham, England
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 Posted: Sun Jun 01, 2008 4:16 pm Post subject: A VH from wapati |
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This puzzle from wapati, published on 16 April 2008, is just a little more than VH:
| Code: | +-----------------------+
| . . . | 1 . . | . 4 9 |
| . 7 . | . . 5 | 6 . . |
| . . 9 | . . . | . . 5 |
-------------------------
| 7 . . | . . 2 | 9 . 4 |
| . . . | . . . | . 5 8 |
| . 8 . | 6 . . | 1 . . |
-------------------------
| . 5 . | 2 . 3 | . . . |
| 4 . . | . 6 . | . . . |
| 9 . 7 | 5 8 . | . . 3 |
+-----------------------+ |
He says it can be solved by a UR and a BUG but I couldn’t find this alternative solution.
Steve |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sun Jun 01, 2008 5:49 pm Post subject: |
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I found UR's on <18> and <23>, but they don't seem to help much.
Keith |
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Steve R
Joined: 24 Oct 2005
Posts: 289
Location: Birmingham, England
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| Posted: Sun Jun 01, 2008 6:52 pm Post subject: |
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No, they don’t. The whole thing seems much more straightforward if uniqueness arguments are set aside.
I did manage to find a second solution path employing the URs but only by using a chain! I never did see a BUG. Probably I missed something simple. I might ask wapati what he had in mind if no one comes up with the answer in the next day or so.
Steve |
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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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| Posted: Sun Jun 01, 2008 7:31 pm Post subject: |
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I used the two URs (simultaneously).
That gets us here:
| Code: |
+--------------------------+--------------------------+--------------------------+
| 56 23 56 | 1 237 8 | 237 4 9 |
| 23 7 8 | 49 49 5 | 6 123 12 |
| 1 4 9 | 37 237 6 | 8 237 5 |
+--------------------------+--------------------------+--------------------------+
| 7 1 35 | 8 35 2 | 9 6 4 |
| 236 9 2346 | 347 1 47 | 237 5 8 |
| 235 8 2345 | 6 34579 479 | 1 237 27 |
+--------------------------+--------------------------+--------------------------+
| 8 5 1 | 2 47 3 | 47 9 6 |
| 4 23 23 | 79 6 179 | 5 8 17 |
| 9 6 7 | 5 8 14 | 24 12 3 |
+--------------------------+--------------------------+--------------------------+
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In this position, there are a whole bunch of (multi-)coloring eliminations:
- 2 from r6c3
- 3 from r1c5,r3c8,r5c1
- 7 from r3c5,r5c7,r6c5,r6c6
after that:
- more coloring on 3
- more coloring on 2
- some xy-wings here:
| Code: |
+--------------------------+--------------------------+--------------------------+
| 5 23 6 | 1 27 8 | 237 4 9 |
| 23 7 8 | 49 49 5 | 6 13 12 |
| 1 4 9 | 37 23 6 | 8 27 5 |
+--------------------------+--------------------------+--------------------------+
| 7 1 35 | 8 35 2 | 9 6 4 |
| 6 9 234 | 347 1 47 | 23 5 8 |
| 23 8 45 | 6 459 49 | 1 37 27 |
+--------------------------+--------------------------+--------------------------+
| 8 5 1 | 2 47 3 | 47 9 6 |
| 4 23 23 | 79 6 179 | 5 8 17 |
| 9 6 7 | 5 8 14 | 24 12 3 |
+--------------------------+--------------------------+--------------------------+
|
- and this BUG+1
| Code: | +--------------------------+--------------------------+--------------------------+
| 5 23 6 | 1 27 8 | 37 4 9 |
| 23 7 8 | 4 9 5 | 6 13 12 |
| 1 4 9 | 37 23 6 | 8 27 5 |
+--------------------------+--------------------------+--------------------------+
| 7 1 35 | 8 35 2 | 9 6 4 |
| 6 9 234 | 37 1 47 | 23 5 8 |
| 23 8 45 | 6 45 9 | 1 37 27 |
+--------------------------+--------------------------+--------------------------+
| 8 5 1 | 2 47 3 | 47 9 6 |
| 4 23 23 | 9 6 17 | 5 8 17 |
| 9 6 7 | 5 8 14 | 24 12 3 |
+--------------------------+--------------------------+--------------------------+ |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sun Jun 01, 2008 8:22 pm Post subject: |
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Ignoring the UR's.
Basics get to here:
| Code: | +-------------------+-------------------+-------------------+
| 2356 23 2356 | 1 237 68 | 2378 4 9 |
| 1238 7 18 | 49 49 5 | 6 123 12 |
| 1236 4 9 | 37 237 68 | 2378 1237 5 |
+-------------------+-------------------+-------------------+
| 7 1 35 | 8 35 2 | 9 6 4 |
| 236 9 2346 | 347 1 47 | 237 5 8 |
| 235 8 2345 | 6 34579 479 | 1 237 27 |
+-------------------+-------------------+-------------------+
| 18 5 18 | 2 47 3 | 47 9 6 |
| 4 23 23 | 79 6 179 | 5 8 17 |
| 9 6 7 | 5 8 14 | 24 12 3 |
+-------------------+-------------------+-------------------+ |
There is an X-wing on <7> in R17. That, and a couple of XY-wings, get you to here:
| Code: | +----------------+----------------+----------------+
| 2356 23d 2356 | 1 -237 68 | 2378 4 9 |
| 1238 7 18 | 4 9 5 | 6 123 12 |
| 1236 4 9 | 37 23a 68 | 238 1237 5 |
+----------------+----------------+----------------+
| 7 1 35@ | 8 35@ 2 | 9 6 4 |
| 236 9 2346 | 37 1 47 | 23 5 8 |
| 235 8 2345 | 6 345 9 | 1 37 27 |
+----------------+----------------+----------------+
| 18 5 18 | 2 47 3 | 47 9 6 |
| 4 23c 23b | 9 6 17 | 5 8 17 |
| 9 6 7 | 5 8 14 | 24 12 3 |
+----------------+----------------+----------------+ |
Now, we get to apply the neat things we have collectively learned in ths forum!
a and b are a W-wing with strong link @ on <3>. Coloring bcd allows us to eliminate <2> in R1C5, solving R3C5 as <2>.
| Code: | +----------------+----------------+----------------+
| 2356 23 2356 | 1 37h 68 |-23-78 4 9 |
| 1238 7 18 | 4 9 5 | 6 123 12d |
| 136 4 9 | 37g 2 68 | 38 137 5 |
+----------------+----------------+----------------+
| 7 1 35 | 8 35 2 | 9 6 4 |
| 236 9 2346 | 37f 1 47 | 23e 5 8 |
| 235 8 2345 | 6 345 9 | 1 37 27 |
+----------------+----------------+----------------+
| 18 5 18 | 2 47 3 | 47b 9 6 |
| 4 23 23 | 9 6 17 | 5 8 17c |
| 9 6 7 | 5 8 14 | 24a 12 3 |
+----------------+----------------+----------------+ |
ab together make <27>. With c and d they form an extended XY-wing, eliminating <2> in R1C7.
There is another extended wing: ab, e, f eliminates <7>. Coloring fgh, we can take out <7> in R1C7. Solving the puzzle.
(Now that I look at it, the elimination of <7> in R1C7 is the move that solves the puzzle. You do not need the first extended wing. Also, I fail to see how the UR's make the puzzle any easier to solve.)
Maybe there is some brilliant deduction on the <35> UR, but I do not see it. Seems like a question for Johan!
Keith |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sun Jun 01, 2008 10:31 pm Post subject: |
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Definitely a fun puzzle.
Type 1 UR on 18
XY-Wing 79-74-94
XY-Wing 17-12-72
Coloring 7
XY-Wing 23-27-37 with pincer coloring |
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Steve R
Joined: 24 Oct 2005
Posts: 289
Location: Birmingham, England
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| Posted: Mon Jun 02, 2008 12:15 pm Post subject: |
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I followed the same path as Keith until it came to the W-Wing. Here is the grid at that point:
| Code: | +--------------------------------------------+
| 2356 23 2356 | 1 237 68 | 2378 4 9 |
| 1238 7 18 | 4 9 5 | 6 123 12 |
| 1236 4 9 | C37 23 68 | 238 C1237 5 |
----------------------------------------------
| 7 1 35 | 8 35 2 | 9 6 4 |
| 236 9 2346 | P37 1 47 | 23 5 8 |
| 235 8 2345 | 6 345 9 | 1 P37 27 |
----------------------------------------------
| 18 5 18 | 2 47 3 | 47 9 6 |
| 4 23 23 | 9 6 17 | 5 8 17 |
| 9 6 7 | 5 8 14 | 24 12 3 |
+--------------------------------------------+ |
The conjugates with respect to 7 in the third row link the (37) pincers in r5c4 and r6c8. This alternative W-Wing eliminates 3 from r5c6 and the puzzle is solved.
Thanks to all, especially nataraj, who actually found the BUG and so enabled me to stop worrying about it.
Steve |
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wapati
Joined: 10 Jun 2008
Posts: 472
Location: Brampton, Ontario, Canada.
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| Posted: Tue Jun 10, 2008 1:12 pm Post subject: Re: A VH from wapati |
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| Steve R wrote: | This puzzle from wapati, published on 16 April 2008, is just a little more than VH:
He says it can be solved by a UR and a BUG but I couldn’t find this alternative solution.
Steve |
Just joined here. I post hard puzzles that don't require chains.
I list possible methods that I find of interest, there are always other "tricks" needed. I don't see UR as very interesting but some people won't use them so if they might be needed I mention. BUG, there are times it is the only non-chain method. |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Tue Jun 10, 2008 3:52 pm Post subject: |
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I essentially followed the path noted by Nataraj with a somewhat different sequence of steps. Including the two initial URs, I needed 13 operations plus clean-ups to complete the puzzle including x-wings, one finned x-wing, both coloring and multiple coloring, one kite, a couple of xy-wings and finally the BUG noted by Nataraj. I expected it to crumble with each new step, but it just kept going and going and going. Fun, Fun, Fun.
Ted |
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