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daj95376
Joined: 23 Aug 2008
Posts: 3854
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 Posted: Thu Apr 29, 2010 4:54 pm Post subject: Puzzle 10/04/29 (A) |
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Basics may prove just as interesting as the non-basic steps.
| Code: | +-----------------------+
| 2 1 . | . . . | . . 6 |
| 6 8 . | . . . | 5 . 9 |
| . . 5 | . . . | . . . |
|-------+-------+-------|
| . . 9 | 2 . 5 | . 3 8 |
| 3 . . | 8 . . | . . 1 |
| . . . | . . 4 | . . . |
|-------+-------+-------|
| . 4 . | . . . | . . 3 |
| . . . | 9 . . | . . . |
| 1 9 . | 5 3 . | 6 . 4 |
+-----------------------+
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Play this puzzle online at the Daily Sudoku site |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Fri Apr 30, 2010 3:12 pm Post subject: |
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Here is where I am after an XY-Wing.
| Code: |
+-------------+------------------+----------------+
| 2 1 347 | 47 5 9 | 348 478 6 |
| 6 8 347 | 147 27 1237 | 5 1247 9 |
| 9 37 5 | 1467 2678 123678 | 1234 1247 27 |
+-------------+------------------+----------------+
| 4 6 9 | 2 1 5 | 7 3 8 |
| 3 257 27 | 8 679 67 | 249 24569 1 |
| 8 257 1 | 3 679 4 | 29 2569 25 |
+-------------+------------------+----------------+
| 57 4 268 | 167 2678 12678 | 1289 125789 3 |
| 57 23 2368 | 9 4 1268 | 128 128 57 |
| 1 9 28 | 5 3 278 | 6 278 4 |
+-------------+------------------+----------------+
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Play this puzzle online at the Daily Sudoku site
There has to be something drastically wrong with my thinking. There is in band 2 a potential DP 57-67-56. The DP killers are a 2 in r56c2, 9 in r56c5 or 249 in r56c8. The latter forms a pseudo cell 249. Every DP killer forces a 5 in r6c9. However, that 5 placed there results in an invalidity. But put a 2 there and I think the puzzle solves OK. Where am I screwing up? |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Fri Apr 30, 2010 4:08 pm Post subject: |
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Marty, that is one messy DP you found 
I follow your analysis of what is needed to prevent the DP, but I am unable to find a path forcing r6c9=5 for r56c2=2 or r56c5=9; maybe I missed something.
Could you post you thinking for those 4 implications?
Ted |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Fri Apr 30, 2010 4:17 pm Post subject: |
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| Marty R. wrote: | Here is where I am after an XY-Wing.
| Code: |
+-------------+------------------+----------------+
| 2 1 347 | 47 5 9 | 348 478 6 |
| 6 8 347 | 147 27 1237 | 5 1247 9 |
| 9 37 5 | 1467 2678 123678 | 1234 1247 27 |
+-------------+------------------+----------------+
| 4 6 9 | 2 1 5 | 7 3 8 |
| 3 257 27 | 8 679 67 | 249 24569 1 |
| 8 257 1 | 3 679 4 | 29 2569 25 |
+-------------+------------------+----------------+
| 57 4 268 | 167 2678 12678 | 1289 125789 3 |
| 57 23 2368 | 9 4 1268 | 128 128 57 |
| 1 9 28 | 5 3 278 | 6 278 4 |
+-------------+------------------+----------------+
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There has to be something drastically wrong with my thinking. There is in band 2 a potential DP 57-67-56. The DP killers are a 2 in r56c2, 9 in r56c5 or 249 in r56c8. The latter forms a pseudo cell 249. Every DP killer forces a 5 in r6c9. However, that 5 placed there results in an invalidity. But put a 2 there and I think the puzzle solves OK. Where am I screwing up? |
I went TILT at the pseudo-cell because all of the cells are not in the same house/unit.
There is a lot that I don't understand about DPs, but one rule that has kept me from wasting a lot of time on them is that a DP can never exist if at least one candidate killer must exist in the first place.
If you examine r56c5, you'll see that candidate killer <9> exists only in these two cells in [c5]. There's no way your <567> DP can be created ... and so there's no way you can proceed on the assumption of that DP. Dead End to the DP. 
With <9> locked in [c5] and <4> locked in [r5b6], I would have passed on a DP being present. But, then again, I miss a lot of DPs.  |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Fri Apr 30, 2010 4:47 pm Post subject: |
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| Quote: | | I follow your analysis of what is needed to prevent the DP, but I am unable to find a path forcing r6c9=5 for r56c2=2 or r56c5=9; maybe I missed something. |
Ted, if r56c2=2, then r5c3=7, r3c2=7, r3c9=2 and thus the 5 in r6c9.
If r5c5=9, then 9s cannot exist on box 6 row 6.
If r6c5=9, then r6c7=2 and r6c9=5.
| Quote: | | I went TILT at the pseudo-cell because all of the cells are not in the same house/unit. |
Danny, I don't know what "TILT" means, but the 249 in the DP cells combine with r56c7 for the 249 triple. (Don't they?)
| Quote: | | If you examine r56c5, you'll see that candidate killer <9> exists only in these two cells in [c5]. There's no way your <567> DP can be created ... and so there's no way you can proceed on the assumption of that DP. Dead End to the DP. |
That, then, presumably is the flaw in my thinking. I'd have never thought of that in a million years. Thanks. |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Fri Apr 30, 2010 5:28 pm Post subject: |
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| That Is Lacking Truth ? |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Fri Apr 30, 2010 5:56 pm Post subject: |
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| Quote: | | If r5c5=9, then 9s cannot exist on box 6 row 6. |
That is an incredible, egregious, embarrassing stupidism. 
I thought of it as soon as I took off for a bike ride. |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Fri Apr 30, 2010 6:08 pm Post subject: |
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| Marty R. wrote: | | Quote: | | If r5c5=9, then 9s cannot exist on box 6 row 6. |
That is an incredible, egregious, embarrassing stupidism.
I thought of it as soon as I took off for a bike ride. |
We have all done it multiple times. I don't view it as being stupid. To me it is simply being so engrossed in something that you can't see/realize the obvious.
(I am not bad at finding rational explanations for my stupid behavior.  )
Ted |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Fri Apr 30, 2010 6:18 pm Post subject: |
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| Mogulmeister wrote: | | That Is Lacking Truth ? |
I guess you are all too young to have ever wasted numerous hours playing pinball and trying to cheat by lifting the table and having the TILT light and alarm go off.
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Fri Apr 30, 2010 6:43 pm Post subject: |
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Talking about being old, it only cost 5 cents to play in my day! 
Ted |
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RiojaKid
Joined: 30 Apr 2010
Posts: 1
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| Posted: Fri Apr 30, 2010 7:12 pm Post subject: |
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| There is also a naked quintuple in c8 ... quite hard to spot, I stared at this for a long time. But once you apply this, a few basic moves and the puzzle is done. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sat May 01, 2010 1:54 am Post subject: |
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| RiojaKid wrote: | | There is also a naked quintuple in c8 ... quite hard to spot, I stared at this for a long time. But once you apply this, a few basic moves and the puzzle is done. |
Another one of the many things that I'm capable of missing.
Welcome to the forum. Stick around and enjoy the insanity.
| Quote: | | I guess you are all too young to have ever wasted numerous hours playing pinball and trying to cheat by lifting the table and having the TILT light and alarm go off. I guess you are all too young to have ever wasted numerous hours playing pinball and trying to cheat by lifting the table and having the TILT light and alarm go off. |
I am an old fossil and spent plenty of time playing pinball machines, bowling when there were pinboys, not automatic pinsetters, driving a car that started with a pedal on the floor, then modernized to start with a push button on the dashboard. Making phone calls with the assistance of a live operator and many other quaint old things. |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Sat May 01, 2010 5:15 am Post subject: |
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| Quote: | | start with a push button on the dashboard |
Now of course quite essential in some sports cars !
| Quote: | That is an incredible, egregious, embarrassing stupidism.
I thought of it as soon as I took off for a bike ride. |
Fortunately the link to one of my own, similar lapses escapes me....... |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Sat May 01, 2010 11:54 am Post subject: |
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Danny,
It is very obvious that you have been extra busy recently but as you can see, no one has posted a solution for this puzzle. I have looked at it twice without success; I was even unable to find the naked quintuple.
When you have the opportunity, please post your solution
Thanks ..............
Ted |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Sat May 01, 2010 12:14 pm Post subject: |
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I needed three steps:
w-wing 28
skyscraper 2
xy-wing 59 |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Sat May 01, 2010 12:59 pm Post subject: |
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Thanks Dan.
I must have messed up basics even though I did it twice. After basics, I only have a single bivalue 28 cell which makes it very difficult to find a w-wing 28. I guess that could also explain the missing quintuple.
Ted |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Sat May 01, 2010 1:48 pm Post subject: |
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| Sorry I was on the wrong puzzle! |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Sat May 01, 2010 2:32 pm Post subject: |
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| Quote: | 1. r38c2 r3c9 <237> ALS  or XY Wing if you prefer with vertex at r3c2: r8c9<>2
2.XY Wing <257> vertex at r6c9: r3c2<>7
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Sat May 01, 2010 3:55 pm Post subject: |
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Remember my comment about basics ? Even the lowly Locked Candidate 1 for <2> is needed to expose the second XY-Wing.
| Code: | c1b7 Locked Pair <> 57 r8c2,r789c3
r3 b2 Locked Candidate 1 <> 8 r3c78
<37+2> XY-Wing r3c2/r3c9+r8c2 <> 2 r8c9
r8 Naked Pair <> 57 r8c68
c8 Hidden Triple *** = 569 r567c8
r6 b6 Locked Candidate 1 * <> 2 r6c2
<25+7> XY-Wing r6c9/r3c9+r6c2 <> 7 r3c2
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wapati
Joined: 10 Jun 2008
Posts: 472
Location: Brampton, Ontario, Canada.
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| Posted: Sat May 01, 2010 6:49 pm Post subject: |
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| tlanglet wrote: | Talking about being old, it only cost 5 cents to play in my day!
Ted |
5 cent cokes, big chocolate bars were a nickel, bread was that or 10 cents.
Are we all creeping up? BTW, I couldn't afford pinball. I may be older.
Bowling alleys always had human pin-setters.
Marty, live operators for phone calls, way to go! |
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