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daj95376
Joined: 23 Aug 2008
Posts: 3854
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 Posted: Sun Jun 20, 2010 9:27 pm Post subject: Puzzle 10/06/20: (B) XY |
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| Code: | +-----------------------+
| 8 5 . | 4 1 . | . . . |
| 1 4 . | 5 . . | . . . |
| . . 3 | 7 . . | . . . |
|-------+-------+-------|
| 6 3 8 | 2 . 7 | . . . |
| 5 . . | . 8 . | . . . |
| . . . | 6 . 3 | . . 8 |
|-------+-------+-------|
| . . . | . . . | 1 6 5 |
| . . . | . . . | 4 2 . |
| . . . | . . 4 | 7 . 9 |
+-----------------------+
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Play this puzzle online at the Daily Sudoku site
| Code: | after basics
+--------------------------------------------------------------+
| 8 5 279 | 4 1 269 | 36 379 267 |
| 1 4 279 | 5 3 269 | 8 79 267 |
| 29 6 3 | 7 29 8 | 5 14 14 |
|--------------------+--------------------+--------------------|
| 6 3 8 | 2 45 7 | 9 145 14 |
| 5 27 24 | 9 8 1 | 36 347 67 |
| 479 79 1 | 6 45 3 | 2 457 8 |
|--------------------+--------------------+--------------------|
| 3479 789 49 | 38 279 29 | 1 6 5 |
| 79 18 6 | 18 79 5 | 4 2 3 |
| 23 12 5 | 13 6 4 | 7 8 9 |
+--------------------------------------------------------------+
# 53 eliminations remain
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peterj
Joined: 26 Mar 2010
Posts: 974
Location: London, UK
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| Posted: Mon Jun 21, 2010 3:33 pm Post subject: |
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First time through this solved using an x-wing and an xy-wing (and maybe a UR1) so went back to look for a more-xy one stepper..
| Quote: | | xy-chain (with ANP) (2=4)r5c3 - (4=79)r68c1 - (7=2)r3c1; r12c3<>2 |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Mon Jun 21, 2010 4:03 pm Post subject: |
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Ouch !!! _  _ _
I was so fixated on an interesting UR solution that I forgot to cross-check the other potential solutions. Here's what caught my attention:
| Code: | after basics: the X-Wing is extraneous
+--------------------------------------------------------------+
| 8 5 279 | 4 1 269 | 36 379 267 |
| 1 4 279 | 5 3 269 | 8 79 267 |
| 29 6 3 | 7 29 8 | 5 *14 *14 |
|--------------------+--------------------+--------------------|
| 6 3 8 | 2 #45 7 | 9 #*145 *14 |
| 5 27 24 | 9 8 1 | 36 347 67 |
| 479 79 1 | 6 #45 3 | 2 #457 8 |
|--------------------+--------------------+--------------------|
| 3479 789 49 | 38 279 29 | 1 6 5 |
| 79 18 6 | 18 79 5 | 4 2 3 |
| 23 12 5 | 13 6 4 | 7 8 9 |
+--------------------------------------------------------------+
# 53 eliminations remain
(*) <14> UR r34c89 (overlapping)
(#) <45> UR r46c58
( <14> UR says r4c8<>14 ) and ( <45> UR says r4c8=1 or r6c8=7 )
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Together, they force r6c8=7 and the puzzle cracks with singles remaining. |
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peterj
Joined: 26 Mar 2010
Posts: 974
Location: London, UK
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| Posted: Mon Jun 21, 2010 5:35 pm Post subject: |
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That's the second of these overlapping URs in as many days... need to up my game on looking for UR moves, just doesn't come naturally!
And you have to play them concurrently for the elimination to appear.. |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Tue Jun 22, 2010 6:24 am Post subject: |
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I think that is what makes this a good puzzle - I too do not automatically look for uniqueness solutions - this one is elegant.
Fwiw, I saw an almost XY Wing <479> formation r68c1,r7c3 with the fin being 9 in r6c1.
If fin is TRUE (47=9)r6c1-(9=2)r3c1-r12c3=(2-4)r5c3 so r5c3<>4
If fin is FALSE then xy-wing<479> and r5c3<>4
Either way puzzle solved.
We know that the fin can not be 9 because the fin = TRUE chain would create no 4 in b4. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Tue Jun 22, 2010 3:49 pm Post subject: |
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Type 1 UR (14)
W-Wing (29) uses both numbers and both were also transported
X-Wing (9)
UR (27) in boxes 13; either DP killer forces r8c1=9 |
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