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competition #1008

 
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Sun Apr 13, 2008 11:06 pm    Post subject: competition #1008 Reply with quote

Code:
5..|.84|..1
...|.7.|.9.
...|...|478
---+---+---
.3.|...|2..
.7.|5.8|.4.
..1|...|.3.
---+---+---
32.|...|...
...|.5.|...
9..|12.|..7


w-wing on {3,6} to start
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Sun Apr 13, 2008 11:23 pm    Post subject: Reply with quote

Yes, but what to end? It has me stumped.

Keith
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Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Mon Apr 14, 2008 3:08 am    Post subject: Reply with quote

I couldn't see a {36} W-Wing. This is the basic grid I got:
Code:
+-------------+-------------+------------+
| 5   9  7    | 23  8   4   | 36   26 1  |
| 124 48 2348 | 236 7   126 | 5    9  23 |
| 12  6  23   | 239 19  5   | 4    7  8  |
+-------------+-------------+------------+
| 46  3  49   | 7   169 169 | 2    8  5  |
| 26  7  29   | 5   3   8   | 1    4  69 |
| 8   5  1    | 269 4   269 | 7    3  69 |
+-------------+-------------+------------+
| 3   2  5    | 8   69  7   | 69   1  4  |
| 7   1  68   | 4   5   369 | 3689 26 23 |
| 9   48 468  | 1   2   36  | 368  5  7  |
+-------------+-------------+------------+

In fact, rather than being a W-Wing, there is an AIC involving those remote {36}s that fixes r9c6 as <3>:
(3=6)r9c6-(6)r9c3=(6)r8c3-(6)r8c78=(6)r789c7-(6=3)r1c7-(3)r2c9
=(3)r8c9-(3)r8c6=(3)r9c6; r9c6=3

While that AIC is not too hard to see (try setting r1c7 to <3> and then to <6> and see that r9c6 is <3> in either case), the puzzle can be solved without it. The easiest route is some fairly simple Medusa Multi-coloring. However, without coloring, here's a path:

(1) 48 UR r29c23: r9c3<>4 and r2c3<>8
(2) 68 Type 4 UR r89c37: r89c7<>6
(3) XY Chain: r3c5-r3c1-r5c1-r4c1-r4c3; r4c5<>9
(4) XY Chain: r9c6-r9c3-r8c3-r8c8-r8c9; r8c6<>3
(5) XYZ Wing, pivot r4c6; r6c6<>6
(6) XY Chain: r6c6-r8c6-r8c8-r8c9-r2c9; r2c6<>2
(7) XY Wing, pivot r2c6; r7c5<>9
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Mon Apr 14, 2008 3:32 am    Post subject: Reply with quote

Quote:
I couldn't see a {36} W-Wing.

<36> in R9C6 and R1C7, with strong link on <6> in R7.

Keith
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Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Mon Apr 14, 2008 4:03 am    Post subject: Reply with quote

Thanks! Now I see it.
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Victor



Joined: 29 Sep 2005
Posts: 207
Location: NI

PostPosted: Mon Apr 14, 2008 6:49 pm    Post subject: Reply with quote

Edit! If you read some stuff I'd written here, please ignore: not for the first time, I didn't think carefully enough & wrote some rubbish.
Final statement still true: thanks S_N - really nice puzzle!
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Earl



Joined: 30 May 2007
Posts: 677
Location: Victoria, KS

PostPosted: Mon Apr 14, 2008 7:58 pm    Post subject: another Reply with quote

Assellus,

Could you do the steps in your two UR's, 48 & 68.
It would help those of us not adept at complex UR's.

Earl
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Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Mon Apr 14, 2008 8:18 pm    Post subject: Re: another Reply with quote

Earl wrote:
Assellus,

Could you do the steps in your two UR's, 48 & 68.
It would help those of us not adept at complex UR's.

Earl

First of all, that extra "s" is appropriate I hope you realize.

The 48 UR is the tricky one. Note that the <8>s in both r2 and c2 are strongly linked. And, note that the <4>s in in both c2 and r9. These are what allow the eliminations.

First, if r2c2 is <4>, then r2c8 must be <8> (due to the strong link), r9c2 is <8>, and r9c3 cannot be <4>. If r2c2 is not <4>, then r9c2 must be <4> (strong link) and r9c3 cannot be <4>. So, r9c3 cannot be <4> in either case.

Next, the <8> situation is done the same way. If r9c2 is <8>, r9c3 and r2c2 must be <4>, so r2c3 cannot be <8>. If r9c2 is not <8>, then r2c2 is <8>. So, r2c3 cannot be <8>.

This solves r9c2 as <4> and the 68 UR becomes a standard Type 4. R89c3 are both {68} bivalues. r89c7 are the "roof," both cells on that side of the UR having extra digits. The <8>s in the roof are strongly linked. Thus, the <6>s are eliminated from both roof cells (whichever of them is <8>, the other cannot be <6>).
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ravel



Joined: 21 Apr 2006
Posts: 536

PostPosted: Tue Apr 15, 2008 10:54 am    Post subject: Reply with quote

A one step solution.
Code:
 *-------------------------------------------------*
 | 5    9   7     | 23   8    4    | 36    26  1   |
 | 124  48  2348  | 236  7    126  | 5     9   23  |
 |*12   6  -23    |#239 *19   5    | 4     7   8   |
 |----------------+----------------+---------------|
 | 46   3   49    | 7    169  169  | 2     8   5   |
 |-26   7  *29    | 5    3    8    | 1     4  #69  |
 | 8    5   1     |@269  4    269  | 7     3  @69  |
 |----------------+----------------+---------------|
 | 3    2   5     | 8    69   7    | 69    1   4   |
 | 7    1   68    | 4    5    369  | 3689  26  23  |
 | 9    48  468   | 1    2    36   | 368   5   7   |
 *-------------------------------------------------*
One of r3c4 and r5c9 must be 9:
r3c4<>9 => r6c4=9 => r6c9=6 => r5c9=9

r3c4=9 => r3c5=1 => r3c1=2
r5c9=9 => r5c3=2
==> r3c3<>2, r5c1<>2
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Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Tue Apr 15, 2008 7:57 pm    Post subject: Reply with quote

ravel,

That's nice... an otherwise useless Skyscraper activating <2> pincers. The same thing falls out quickly with Medusa multi-coloring.
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