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daj95376
Joined: 23 Aug 2008
Posts: 3854
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 Posted: Tue Jul 13, 2010 4:58 pm Post subject: Puzzle 10/07/13: XY+ |
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You may wish to consider more than one step.
| Code: | +-----------------------+
| . . . | 3 . 6 | . 8 . |
| . 5 . | . 7 2 | . 4 . |
| . . 7 | . 9 4 | . . . |
|-------+-------+-------|
| 5 . . | . 3 8 | . . . |
| . 1 8 | 9 2 5 | . . . |
| 7 3 9 | 6 4 . | 5 2 . |
|-------+-------+-------|
| . . . | . . 9 | 8 . . |
| 1 2 . | . . 7 | . 3 9 |
| . . . | . . . | . 5 . |
+-----------------------+
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Play this puzzle online at the Daily Sudoku site
| Code: | after basics
+-----------------------------------------------------------------------+
| 249 49 14 | 3 15 6 | 1279 8 1257 |
| 3689 5 136 | 18 7 2 | 1369 4 136 |
| 2368 68 7 | 158 9 4 | 1236 16 12356 |
|-----------------------+-----------------------+-----------------------|
| 5 46 2 | 7 3 8 | 146 9 146 |
| 46 1 8 | 9 2 5 | 346 7 346 |
| 7 3 9 | 6 4 1 | 5 2 8 |
|-----------------------+-----------------------+-----------------------|
| 346 7 3456 | 1245 156 9 | 8 16 1246 |
| 1 2 456 | 45 8 7 | 46 3 9 |
| 89 89 46 | 124 16 3 | 12467 5 12467 |
+-----------------------------------------------------------------------+
# 78 eliminations remain
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Tue Jul 13, 2010 6:36 pm Post subject: |
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xy-wing -146 with vertex (46)r9c3; r1c5<>1
ANP(46=5)r89c3-(5=4)r8c4-(4=6)r8c7-(6=1)r7c8-r3c8=r3c4-(1=8)r2c4-(8=6)r2c1-(6=4)r5c1; r7c1<>4
Which leaves us with the following interesting code.
| Code: | *--------------------------------------------------------------------*
| 49 49 1 | 3 5 6 | 27 8 27 |
| 68 5 3 | 18 7 2 | 9 4 16 |
| 2 68 7 | 18 9 4 | 3 16 5 |
|----------------------+----------------------+----------------------|
| 5 46 2 | 7 3 8 | 1 9 46 |
| 46 1 8 | 9 2 5 | 46 7 3 |
| 7 3 9 | 6 4 1 | 5 2 8 |
|----------------------+----------------------+----------------------|
| 3 7 45 | 245 16 9 | 8 16 24 |
| 1 2 456 | 45 8 7 | 46 3 9 |
| 89 89 46 | 24 16 3 | 27 5 12467 |
*--------------------------------------------------------------------* |
Two solutions at this stage are a
Type 1 UR27 r19c79; r9c9<>27 plus a BUG+1 forces r9c9=6, or
coloring on (6) which deletes a bunch.
Ted |
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peterj
Joined: 26 Mar 2010
Posts: 974
Location: London, UK
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| Posted: Fri Jul 16, 2010 2:23 pm Post subject: |
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Not sure how best to notate this but the obvious xy-wing with one pincer at r1c3 is the start of a doubled pronged xy attack on 1s...
| Code: | (4=6)r9c3 - (6=1)r9c5; r1c5<>1
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(1=4)r1c3
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(4=9)r1c2 - (9=8)r9c2 - (8=6)r3c2 - (6=1)r3c8; r1c79<>1 |
Then, as Ted says, one of many possible turbot/colouring moves on 6 polishes it off.
Is there something that can be done with the overlapping AUR(45) and AUR(46) at bottom of grid? |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Fri Jul 16, 2010 3:32 pm Post subject: |
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| peterj wrote: | Not sure how best to notate this but the obvious xy-wing with one pincer at r1c3 is the start of a doubled pronged xy attack on 1s...
| Code: | (4=6)r9c3 - (6=1)r9c5; r1c5<>1
/
(1=4)r1c3
\
(4=9)r1c2 - (9=8)r9c2 - (8=6)r3c2 - (6=1)r3c8; r1c79<>1 |
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Peter, it is good to see your contributions again; they are frequently different/unique as is the case here.
I would have found and posted your two branches as separate steps; a xy-wing -146 with vertex (46)r9c3 and an AIC found by extending the vertex of a potential xy-wing -149 with vertex (49)r1c2. As I have previously noted, finding chains gives me great difficulties and the ones I do find are normally based on extending the vertex of a potential xy-wing.
Ted |
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