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May 26, VH

 
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crunched



Joined: 05 Feb 2008
Posts: 168

PostPosted: Tue May 26, 2009 4:50 am    Post subject: May 26, VH Reply with quote

Where is the Earlster?
Here is the grid after basics. It proved to be a one-stepper for me. I did the whole puzzle in about 10 minutes. That means the wizards here probably solved it in about 30 seconds.

Code:

+---------+-----------+-----------+
| 68 3  2 | 14  9  17 | 5 48 4678 |
| 1  58 4 | 6   57 2  | 9 3  78   |
| 56 9  7 | 45  8  3  | 2 1  46   |
+---------+-----------+-----------+
| 58 58 9 | 7   1  6  | 4 2  3    |
| 3  2  1 | 458 45 48 | 6 7  9    |
| 4  7  6 | 3   2  9  | 8 5  1    |
+---------+-----------+-----------+
| 9  1  3 | 2   6  48 | 7 48 5    |
| 7  4  8 | 9   3  5  | 1 6  2    |
| 2  6  5 | 148 47 17 | 3 9  48   |
+---------+-----------+-----------+

Play this puzzle online at the Daily Sudoku site
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Tue May 26, 2009 5:46 am    Post subject: Reply with quote

crunched,
you have a pointing pair of 4's in column 4 in box 2.
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arkietech



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

PostPosted: Tue May 26, 2009 11:54 am    Post subject: Reply with quote

One step:
Quote:
a 468 xy-wing did it for me
An easy one.
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giadich



Joined: 15 May 2009
Posts: 3

PostPosted: Tue May 26, 2009 4:00 pm    Post subject: Reply with quote

The HARD rated puzzle on 5-24 is much harder than this one 5-26!
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Clement



Joined: 24 Apr 2006
Posts: 1110
Location: Dar es Salaam Tanzania

PostPosted: Tue May 26, 2009 6:52 pm    Post subject: Daily Sudoku: Tue 26-May-2009 VH Reply with quote

BUG 1 Solves the puzzle.
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Wendy W



Joined: 04 Feb 2008
Posts: 144

PostPosted: Tue May 26, 2009 11:27 pm    Post subject: Reply with quote

Really easy. I thought I'd make a mistake, it was falling apart so quickly (NO -- how could that be). After basics the first XY-wing solved the whole thing.
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crunched



Joined: 05 Feb 2008
Posts: 168

PostPosted: Tue May 26, 2009 11:57 pm    Post subject: Reply with quote

storm_norm wrote:
crunched,
you have a pointing pair of 4's in column 4 in box 2.


Yep, you are correct. Below is the grid after the "pointing pair" takes out a coupla 4s:

Wendy, I had the same good fortune, that the 1st xy wing solved the puzzle. However, note how many xy-wings are in this puzzle: 4-5-8, 1-4-8, 4-5-7 & 4-6-8. Those other than the 4-6-8 are not worth anything from what I can find. Usually my luck is to have the find the last xy-wing to do any good.
Code:

+---------+----------+-----------+
| 68 3  2 | 14 9  17 | 5 48 4678 |
| 1  58 4 | 6  57 2  | 9 3  78   |
| 56 9  7 | 45 8  3  | 2 1  46   |
+---------+----------+-----------+
| 58 58 9 | 7  1  6  | 4 2  3    |
| 3  2  1 | 58 45 48 | 6 7  9    |
| 4  7  6 | 3  2  9  | 8 5  1    |
+---------+----------+-----------+
| 9  1  3 | 2  6  48 | 7 48 5    |
| 7  4  8 | 9  3  5  | 1 6  2    |
| 2  6  5 | 18 47 17 | 3 9  48   |
+---------+----------+-----------+

Play this puzzle online at the Daily Sudoku site
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cgordon



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

PostPosted: Wed May 27, 2009 1:57 pm    Post subject: Reply with quote

I saw a different xy wing using <478>. But I don't see Clement's Bug+1 with all those triples still remaining.
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Marty R.



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

PostPosted: Wed May 27, 2009 3:40 pm    Post subject: Reply with quote

cgordon wrote:
I saw a different xy wing using <478>. But I don't see Clement's Bug+1 with all those triples still remaining.

The original posted grid had locked 4s which made eliminations. Look at Crunched's grid right above your post.
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cgordon



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

PostPosted: Wed May 27, 2009 4:17 pm    Post subject: Reply with quote

Yes - I missed that - but still don't see how to use a Bug+1 with a quad left.
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Marty R.



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

PostPosted: Wed May 27, 2009 4:42 pm    Post subject: Reply with quote

cgordon wrote:
Yes - I missed that - but still don't see how to use a Bug+1 with a quad left.

Well, I'm not 100% sure of the logic, but someone will let me know if it's wrong. If you remove the 4 and 8 from the quad cell you'd be left with the BUG pattern. Thus it needs to be 4 or 8 to kill the BUG.
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Wed May 27, 2009 6:43 pm    Post subject: Reply with quote

Marty R. wrote:
cgordon wrote:
Yes - I missed that - but still don't see how to use a Bug+1 with a quad left.

Well, I'm not 100% sure of the logic, but someone will let me know if it's wrong. If you remove the 4 and 8 from the quad cell you'd be left with the BUG pattern. Thus it needs to be 4 or 8 to kill the BUG.


Marty,
that is some awesome logic. Idea Idea Idea

r1c9 <> 67
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cgordon



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

PostPosted: Wed May 27, 2009 7:20 pm    Post subject: Reply with quote

Quote:
Marty, that is some awesome logic

I once read that a BUG was an acronym for a Bivalue Universal Grave – which sounds more like something from Shawn of the Dead. I just remember techniques by rote. Thus: if there’s one triple left in the puzzle -say 123, and it sees a 13 and a 23 – shove the no that occurs three times (ie. 3) in place of the triple. Marty’s logic requires too much painful thinking. Confused
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Wendy W



Joined: 04 Feb 2008
Posts: 144

PostPosted: Thu May 28, 2009 12:15 am    Post subject: Reply with quote

CG, that is the best and most easily understandable explanation of a BUG I've ever seen.
Would you please get a job writing cell phone manuals?
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Clement



Joined: 24 Apr 2006
Posts: 1110
Location: Dar es Salaam Tanzania

PostPosted: Sat May 30, 2009 5:45 pm    Post subject: Daily Sudoku: Tue 26-May-2009 VH Reply with quote

Storm_norm wrote:
Quote:
Marty,
that is some awesome logic

The 4 in r1c9 is removed by the XY-Wing (148) with pivot(18)r9c4 and that cell(r1c9) remains with three candidates (678). All the remaining cells are bi-value, hence, the BUG pattern Smile
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Sat May 30, 2009 11:56 pm    Post subject: Re: Daily Sudoku: Tue 26-May-2009 VH Reply with quote

Clement wrote:
Storm_norm wrote:
Quote:
Marty,
that is some awesome logic

The 4 in r1c9 is removed by the XY-Wing (148) with pivot(18)r9c4 and that cell(r1c9) remains with three candidates (678). All the remaining cells are bi-value, hence, the BUG pattern Smile


or
because of the BUG either r1c9 is 4 or 8... BUG[(4=8)r1c9]

BUG[(8=4)r1c9] - (4=1)r1c4 - (1=8)r9c4; means r9c9 <> 8
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