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Puzzle 11/07/25: B XY

 
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Mon Jul 25, 2011 4:04 pm    Post subject: Puzzle 11/07/25: B XY Reply with quote

The extraneous steps may drive you to drink!

Code:
 +-----------------------+
 | . . 5 | . 9 . | 3 . . |
 | . 7 . | 5 4 . | 1 . . |
 | 1 . . | . . . | . . . |
 |-------+-------+-------|
 | . 4 . | 1 . 2 | . 8 . |
 | 8 5 . | . 6 . | . . 1 |
 | . . . | 8 . 4 | 9 . 6 |
 |-------+-------+-------|
 | 6 9 . | . . 5 | . . . |
 | . . . | 6 . . | . 9 . |
 | . . . | . 3 9 | . . 4 |
 +-----------------------+

Play this puzzle online at the Daily Sudoku site
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peterj



Joined: 26 Mar 2010
Posts: 974
Location: London, UK

PostPosted: Tue Jul 26, 2011 7:24 am    Post subject: Reply with quote

Two wings - already there on the drink front so extraneous steps had no effect...
Quote:
w-wing(2-8) r3c5, r9c2 ; r3c2<>8
xy-wing(28-6) r3c5 ; r3c6<>6
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tlanglet



Joined: 17 Oct 2007
Posts: 2461
Location: Northern California Foothills

PostPosted: Wed Jul 27, 2011 2:39 pm    Post subject: Reply with quote

Two "Conflict" steps........

(3=1)r8c2-aur(13)r68c23[(1)r7c3=(3)r2c3*]-(3=2)r2c1#-(2=6)r2c8-(6=8)r2c6-(8=2)r3c5-r78c5=r9c4-r9c2=r13c2- Conflict#; r2c3<>3, r7c3=1, r8c3*<>3(?)

axy-wing (28-6)b2q86+r3c2=(8)r3c2-(8=2)r9c2-r9c4=r1c4-(2=8r3c5- Conflict; r3c2<>8, r3c6<>6

In the first step, I have marked a deletion when within the aur, r2c3 is set to 3, but later it is determined that r2c3 can not be 3 due to a conflict.
Question: Is the deletions based on r2c3=3 valid?

Finally the first step is not required; the second move is a one-stepper.

Ted
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Wed Jul 27, 2011 3:40 pm    Post subject: Reply with quote

Ted, the first step can be broken into two, more manageable steps.

Code:
(2=6)r2c8-(6=8)r2c6-(8=2)r3c5-r78c5=r9c4-r9c2=(2)r13c2; r2c1<>2=3

 r68c23  <13> UR Type 4.2245             <> 1    r68c3

As for the first part of your chain ...

Code:
(3=1)r8c2-aur(13)r68c23[(1)r7c3=(3)r2c3]; r8c3<>3

... doesn't r8c3<>3 follow from (a Hidden UR ?):

Code:
(3*)r8c3 - (3=1*)r8c2 - (1   )r6c2 = (1*)r6c3  =>  *DP in <13>
                        ( =3*)r6c2
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Luke451



Joined: 20 Apr 2008
Posts: 310
Location: Southern Northern California

PostPosted: Wed Jul 27, 2011 6:42 pm    Post subject: Reply with quote

tlanglet wrote:
axy-wing (28-6)b2q86+r3c2=(8)r3c2-(8=2)r9c2-r9c4=r1c4-(2=8)r3c5- Conflict; r3c2<>8, r3c6<>6

V cool almost xy Ted, I like it. A wee point: I don't understand why you've started ending your chains with "-conflict" rather than writing a standard ending that proves the conflict; -(8=6)r2c6 =>r3c6<>6
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tlanglet



Joined: 17 Oct 2007
Posts: 2461
Location: Northern California Foothills

PostPosted: Thu Jul 28, 2011 1:17 pm    Post subject: Reply with quote

[quote="Luke451"]
tlanglet wrote:
axy-wing (28-6)b2q86+r3c2=(8)r3c2-(8=2)r9c2-r9c4=r1c4-(2=8)r3c5- Conflict; r3c2<>8, r3c6<6>r3c6<>6

Luke, Great Question (as I constantly hear folks respond)!

First, I am not sure why I stopped with "-conflict" but I also (always?) have in the past. It is at the same stage as when a deletion normally occurs: (8)r3c2- ...... =(8)r3c5. Also, I am not sure how to flag the conflict otherwise in order to delete the source of the conflict. I guess ideally that it would be best to continue the chain to the normal end but flag the conflict within the chain.

Ted
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