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Nov 6 VH
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Earl



Joined: 30 May 2007
Posts: 677
Location: Victoria, KS

PostPosted: Thu Nov 06, 2008 2:58 am    Post subject: Nov 6 VH Reply with quote

I needed two steps: x-wing (2) then xy-wing (269).

Earl
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kragzy



Joined: 01 May 2007
Posts: 112
Location: Australia

PostPosted: Thu Nov 06, 2008 3:03 am    Post subject: Reply with quote

me two too
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arkietech



Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA

PostPosted: Thu Nov 06, 2008 3:41 am    Post subject: Reply with quote

Code:
 *-----------*
 |...|1.8|...|
 |4..|...|8.2|
 |.1.|.4.|73.|
 |---+---+---|
 |.7.|.85|.61|
 |...|...|...|
 |36.|47.|.8.|
 |---+---+---|
 |.39|.5.|.4.|
 |1.8|...|..3|
 |...|8.1|...|
 *-----------*

I did not need the x-wing just the 269 xy-wing
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Thu Nov 06, 2008 4:45 am    Post subject: Reply with quote

I used one W-Wing on 69. Sounds like it might've been part of the aforementioned 269 XY-Wing.
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cgordon



Joined: 04 May 2007
Posts: 769
Location: ontario, canada

PostPosted: Thu Nov 06, 2008 1:43 pm    Post subject: Reply with quote

I think the goal here is to look for a single step. I used <269> xy-wing but had to use it twice with pivot in R1C2 then with pivot in R3C3. Didn't see it as the one-step noted by Dan. But I was wrong once before.
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Thu Nov 06, 2008 4:45 pm    Post subject: Reply with quote

Quote:
But I was wrong once before.

I presume that was the first time that you said you were once wrong? Laughing
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Clement



Joined: 24 Apr 2006
Posts: 1111
Location: Dar es Salaam Tanzania

PostPosted: Thu Nov 06, 2008 5:32 pm    Post subject: Daily Sudoku: Thu 6-Nov-2008 VH Reply with quote

X-Wing in 2's r18c25 is all what was needed.
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arkietech



Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA

PostPosted: Thu Nov 06, 2008 6:49 pm    Post subject: Reply with quote

cgordon wrote:
I think the goal here is to look for a single step.

I come across many logical eliminations while working a puzzle. Most do not contribute to the solution. I try to eliminate these when discussing how a puzzle was solved. I think the goal should be to show only steps needed to solve rather than all steps encountered. In reviewing the puzzle I did find I needed a x-wing after the xy-wing. I don't know how I did it the first time. This is not the first time I have done something dumb like that. Embarassed
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Thu Nov 06, 2008 10:02 pm    Post subject: Reply with quote

arkietech was originally correct. I suspect that one of the eliminations was missed when trying to re-create his solution.

Code:
 after basics but sans X-Wing
 XY-Wing  [r3c3]/[r1c2]+[r3c9] => [r1c78]<>9
 puzzle subsequently solves with Naked Pair and Singles
 *-----------------------------------------------------------*
 | 7     29    3     | 1     269   8     | 56-9  5-9   4     |
 | 4     59    56    | 37    69    37    | 8     1     2     |
 | 8     1     26    | 5     4     269   | 7     3     69    |
 |-------------------+-------------------+-------------------|
 | 29    7     24    | 239   8     5     | 34    6     1     |
 | 259   8     245   | 2369  1     2369  | 34    29    7     |
 | 3     6     1     | 4     7     29    | 259   8     59    |
 |-------------------+-------------------+-------------------|
 | 26    3     9     | 267   5     267   | 1     4     8     |
 | 1     25    8     | 269   269   4     | 256   7     3     |
 | 256   4     7     | 8     3     1     | 2569  259   569   |
 *-----------------------------------------------------------*
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Thu Nov 06, 2008 10:16 pm    Post subject: Reply with quote

The W-Wing I used is present in Danny's grid. The 69s in boxes 23 are connected by the 6s in row 1.
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Thu Nov 06, 2008 11:27 pm    Post subject: Reply with quote

Marty R. wrote:
I used one W-Wing on 69. Sounds like it might've been part of the aforementioned 269 XY-Wing.

Although your W-Wing has one cell in common with the XY-Wing, the elimination is different.

However, if you'd found the M-Wing, then the eliminations would have been the same as the XY-Wing, and all of its cells would have been present in the M-Wing. Then Asellus could have told you that your solution was an XY-Wing with a mustache. Very Happy
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Fri Nov 07, 2008 1:08 am    Post subject: Reply with quote

daj95376 wrote:
Marty R. wrote:
I used one W-Wing on 69. Sounds like it might've been part of the aforementioned 269 XY-Wing.

Although your W-Wing has one cell in common with the XY-Wing, the elimination is different.

However, if you'd found the M-Wing, then the eliminations would have been the same as the XY-Wing, and all of its cells would have been present in the M-Wing. Then Asellus could have told you that your solution was an XY-Wing with a mustache. Very Happy

Are you sure there wasn't also a Sashimi Franken Sue de what's her name Ariadne's thread BUG lite bifurcation in there as well? Laughing
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Fri Nov 07, 2008 5:10 am    Post subject: Reply with quote

Quote:
Are you sure there wasn't also a Sashimi Franken Sue de what's her name Ariadne's thread BUG lite bifurcation in there as well?


remember the show called "V". that episode where the woman had a lizard as a baby?

this is what happens when franken sue gets married to ariadne, they have FISH !!
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Fri Nov 07, 2008 5:38 am    Post subject: Reply with quote

Marty R. wrote:
Are you sure there wasn't also a Sashimi Franken Sue de what's her name Ariadne's thread BUG lite bifurcation in there as well? Laughing

Yeah Exclamation Exclamation Exclamation Exclamation Exclamation Exclamation One of them too Exclamation Laughing
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Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Fri Nov 07, 2008 6:03 am    Post subject: Reply with quote

Norm wrote:
this is what happens when franken sue gets married to ariadne, they have FISH !!

Seems only appropriate since Ariadne's half-brother was the minotaur, the offspring of Ariadne's mother and a bull.

Is there actually a sudoku technique named Ariadne's Thread, or do you only wish there were, Marty?

By the way, I picture that mustache attached to a pair of those funny glasses. They don't fool me! I can still see that XY-Wing!
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Fri Nov 07, 2008 6:08 am    Post subject: Reply with quote

Quote:
Is there actually a sudoku technique named Ariadne's Thread, or do you only wish there were, Marty?

Excerpt from Sudopedia:

"Ariadne's Thread is the name used for a method to solve a complex problem, such as a Sudoku puzzle, by exploring possible alternatives, backtracking when an error is encountered. The process ends when either no more alternatives are available, or when a valid solution is found."

I always check first before I make fun of the language of Sudoku (which is always great fun). Laughing
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Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Fri Nov 07, 2008 6:17 am    Post subject: Reply with quote

Marty wrote:
Excerpt from Sudopedia:


Ah! I'm disappointed. It sounds inaptly named. In mythology, Ariadne's thread was magical and was able to unroll itself precisely in the solution to Daedalus's otherwise virtually insoluable labyrinth.
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Fri Nov 07, 2008 9:25 am    Post subject: Reply with quote

yes, definitely not aptly named. ariadne's thread sounds like a recursive algorithm. its the opposite of what the magical being would do since when you find your way through a maze, you yourself act as a recursive program. the magical being doesn't back track.
Medusa and Kraken are other myth names. Kraken being the large squid. But if I remember a movie "clash of the Titans" the Kraken was a very large four armed human/fish/whatever. The kraken was turned into stone when Perseus revealed the head of medusa.

oh poor poseidon. Medusa was the woman he use to love. in fact, she was turned into medusa because she was caught in aphrodites temple with poseidon. The Kraken was the creature he was in charge of and they were both destroyed. how is that for a bad day?
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cgordon



Joined: 04 May 2007
Posts: 769
Location: ontario, canada

PostPosted: Fri Nov 07, 2008 1:18 pm    Post subject: Reply with quote

Actually, Theseus, with Ariadne’s help, escaped from the labyrinth built by Daedalus. But then Daedalus got incarcerated and managed to escape with his son Icarus using wings. But Icarus failed to listen to his wise father. He didn’t use his wings properly and his journey came to an incomplete end. The moral of the story for some of you above:
“Listen to the ‘wise’ – you can’t finish with just one set of wings."
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daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Fri Nov 07, 2008 4:42 pm    Post subject: Reply with quote

Ariadne's Thread:

I don't have a direct quote on why it's aptly named, so I'll paraphrase the explanation I read awhile back.

Ariadne's boyfriend/son/??? had to go into a labyrinth for some reason and then find his way back out. He used the string she provided to help him search the labyrinth using a Depth-First Search approach (like placing your hand on the wall while walking through a maze). Once he found what he was after, he used the thread to find his way out.

It was a pure brute-force approach with backtracking!
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