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daj95376
Joined: 23 Aug 2008
Posts: 3854
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 Posted: Sun Mar 20, 2011 6:11 pm Post subject: Puzzle 11/03/20: ~ Difficult BBDB |
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| Code: | +-----------------------+
| . . 1 | 2 8 . | . 9 . |
| . 5 . | . . . | . 1 . |
| 8 . 9 | . . . | . . . |
|-------+-------+-------|
| 4 . . | 7 1 . | . 2 5 |
| 7 . . | 6 . 9 | 1 4 8 |
| . . . | . 5 . | . . 3 |
|-------+-------+-------|
| . . . | . 4 . | . . . |
| 2 8 . | 5 3 . | . 6 . |
| . . . | 9 6 2 | . . . |
+-----------------------+
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Play this puzzle online at the Daily Sudoku site |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Sun Mar 20, 2011 8:31 pm Post subject: |
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An aur() and two standard moves does the trick......
| Quote: | aur(47)r89c37 internal sis: r9c3=3,r9c7=35; r3c7<>2
(3)r9c3-(3=6)r7c3-(6=2)r6c3-r6c2=r3c2;
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np(35)r7c8|r9c7-(35=2)r7c7
kite (7) hinge b1; r9c9<>7=4
BUG+1; r3c7=5 |
Ted |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Sun Mar 20, 2011 8:45 pm Post subject: |
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#1...the most interesting thing I found with this puzzle is that finned x-wing on 7's in columns 2 and 7 can also be seen as a almost skyscraper.
| Code: | +------------------+----------+-------------------+
| 3 4(7) 1 | 2 8 56 | 45(7) 9 467 |
| 6 5 (27) | 3 9 4 | 8 1 27 |
| 8 24 9 | 1 7 56 | 2345 35 246 |
+------------------+----------+-------------------+
| 4 69 8 | 7 1 3 | 69 2 5 |
| 7 3 5 | 6 2 9 | 1 4 8 |
| 19 1269 (26) | 4 5 8 | 69 7 3 |
+------------------+----------+-------------------+
| 159 169 (36) | 8 4 7 | 235 35 12 |
| 2 8 4-7 | 5 3 1 | 4(7) 6 9 |
| 15 1(7) 47(3) | 9 6 2 | 45(37) 8 147 |
+------------------+----------+-------------------+ |
ok, so the almost skyscraper would be (7)r9c2 = (7)r1c2 - (7)r1c7 = (7)r8c7
if that skyscraper is true, then the 7 in r8c3 is obviously eliminated.
but, the 7 in r9c7 is stopping all that from happening.
so if the skyscraper is false, then the 7 in r9c7 is true, leads too this kraken column 7... it says that r8c3 is not 7
(7-3)r9c7 = (3)r9c3 - (3=6)r7c3 - (6=2)r6c3 - (2=7)r2c3
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(7)r8c7
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(7)r1c7 - (7)r2c7 = (7)r9c2
| Code: |
+------------------+----------+----------------+
| 3 4(7) 1 | 2 8 56 | 45 9 467 |
| 6 5 2(7) | 3 9 4 | 8 1 (27) |
| 8 24 9 | 1 7 56 | 2345 35 246 |
+------------------+----------+----------------+
| 4 69 8 | 7 1 3 | 69 2 5 |
| 7 3 5 | 6 2 9 | 1 4 8 |
| 19 1269 26 | 4 5 8 | 69 7 3 |
+------------------+----------+----------------+
| 59-1 69-1 36 | 8 4 7 | 235 35 (12) |
| 2 8 4 | 5 3 1 | 7 6 9 |
| 15 (17) 37 | 9 6 2 | 345 8 4-1 |
+------------------+----------+----------------+ |
#2... (1=7)r9c2 - (7)r1c2 = (7)r2c3 - (7=2)r2c9 - (2=1)r7c9; r7c12 and r9c9 not 1
#3... BUG+1... r3c7 = 5 |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Sun Mar 20, 2011 10:40 pm Post subject: |
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Norm, It is surreal that you posted an almost skyscraper because I worked the dame pattern in daj 11/03/18 Moderate BBDB; almost skyscraper(5)r9c35 with fin (5)r6c5. sorry to say, I was unable to obtain additional deletions other than the normal finned x-wing deletion.
Ted |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Mon Mar 21, 2011 2:30 am Post subject: |
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| storm_norm wrote: | #1...the most interesting thing I found with this puzzle is that finned x-wing on 7's in columns 2 and 7 can also be seen as a almost skyscraper.
| Code: | +------------------+----------+-------------------+
| 3 4(7) 1 | 2 8 56 | 45(7) 9 467 |
| 6 5 (27) | 3 9 4 | 8 1 27 |
| 8 24 9 | 1 7 56 | 2345 35 246 |
+------------------+----------+-------------------+
| 4 69 8 | 7 1 3 | 69 2 5 |
| 7 3 5 | 6 2 9 | 1 4 8 |
| 19 1269 (26) | 4 5 8 | 69 7 3 |
+------------------+----------+-------------------+
| 159 169 (36) | 8 4 7 | 235 35 12 |
| 2 8 4-7 | 5 3 1 | 4(7) 6 9 |
| 15 1(7) 47(3) | 9 6 2 | 45(37) 8 147 |
+------------------+----------+-------------------+ |
ok, so the almost skyscraper would be (7)r9c2 = (7)r1c2 - (7)r1c7 = (7)r8c7
if that skyscraper is true, then the 7 in r8c3 is obviously eliminated.
but, the 7 in r9c7 is stopping all that from happening.
so if the skyscraper is false, then the 7 in r9c7 is true, leads too this kraken column 7... it says that r8c3 is not 7
(7-3)r9c7 = (3)r9c3 - (3=6)r7c3 - (6=2)r6c3 - (2=7)r2c3
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(7)r8c7
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(7)r1c7 - (7)r1c2 = (7)r9c2
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First, an interesting find!!!
The problem, for me, with almost structures containing a fin candidate is that the fin candidate is often false. So, I have a hard time assuming that a fin candidate is true ... instead of trying to eliminate it first.
Norm's cells can be used to eliminate the fin candidate:
| Code: | (7)r9c23 = (7)r98c3 - als(7=3)r267c3 - (3)r9c3 = (3)r9c7 => r9c7<>7
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Afterwards, it's no longer an almost Skyscraper. |
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peterj
Joined: 26 Mar 2010
Posts: 974
Location: London, UK
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| Posted: Mon Mar 21, 2011 7:41 am Post subject: |
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Three steps also
| Code: | anp(2=35)r7c89 - (3=6)r7c3 - (6=2)r6c3 - r2c3=r2c9 ; r3c7<>2, r7c9<>2
kite(7) c2, r2 ; r9c9<>7
BUG+1 ; r3c7=5 |
Ted, my ANP seems to be the first chain in your AUR stream. |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Mon Mar 21, 2011 2:06 pm Post subject: |
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| daj95376 wrote: |
The problem, for me, with almost structures containing a fin candidate is that the fin candidate is often false. So, I have a hard time assuming that a fin candidate is true ... instead of trying to eliminate it first.
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Danny, Trying first to determine if a fin may be eliminated seems, to me, to be a waste of effort because it is still necessary to determine what eliminations the almost pattern provides if the fin may not be eliminated. Assuming the fin is true is the same amount of effort but directly provides the desired info: either it provides some common deletions as the basic pattern or it doesn't.
Ted |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Tue Mar 22, 2011 11:23 pm Post subject: |
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I can usually find a longer way and this was no exception.
Skyscraper, XY-Chain, two XY-Wings, Type 1 UR and flightless W-Wing. |
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