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MM Diabolical June 3, 2007

 
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keith



Joined: 19 Sep 2005
Posts: 3178
Location: near Detroit, Michigan, USA

PostPosted: Mon Jun 04, 2007 5:13 am    Post subject: MM Diabolical June 3, 2007 Reply with quote

Did you try this one?
Code:
Puzzle: MM060307  Diabolical
+-------+-------+-------+
| . . 3 | . 6 . | 5 . . |
| 1 . . | . . . | . . 9 |
| . . 2 | 4 . 8 | . 1 . |
+-------+-------+-------+
| 8 2 . | 3 . 7 | . 5 . |
| . . . | . . . | . . . |
| . 3 . | 2 . 9 | . 8 7 |
+-------+-------+-------+
| . 9 . | 8 . 4 | 7 . . |
| 5 . . | . . . | . . 1 |
| . . 6 | . 3 . | 4 . . |
+-------+-------+-------+

You can do the "usual" advanced stuff, or you can solve R1C9.
Keith
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Mogulmeister



Joined: 03 May 2007
Posts: 695

PostPosted: Wed Jun 06, 2007 4:10 am    Post subject: Reply with quote

Nice puzzle- I worked this through twice and indeed, focussing on just r1c9 and using just strong links theory managed to solve r1c9 and after that the puzzle resolved easily. If you don't do that, then the puzzle needs more lengthy use of other techniques.

Provoked 2 thoughts:

1)What thought process leads to singling out r1c9 ?

2)I'm not sure I'd have seen it and would have ploughed on with x-wings etc
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Mogulmeister



Joined: 03 May 2007
Posts: 695

PostPosted: Wed Jun 06, 2007 10:45 pm    Post subject: Reply with quote

Well I've thought about point 1.

It is clear with this puzzle that the 8's are very nicely aligned in conjugate pairs - in fact there are two x-wings sitting one inside the other so crack one of those 8's and the rest being connected will tumble.


If we look at the grid early on:



We see 2 strong link structures in orange (2's) pincers at r1c6 r7c9 and pink (4's) pincers at r1c1 and r4c9 both eliminate their respective candidates in r1c9 leaving only 8. When this is done the puzzle unravels easily.
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Marty R.



Joined: 12 Feb 2006
Posts: 5164
Location: Rochester, NY, USA

PostPosted: Thu Jun 07, 2007 4:34 am    Post subject: Reply with quote

The 15-25-12 XY-Wing based in r9c6 was all that was needed.
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Mogulmeister



Joined: 03 May 2007
Posts: 695

PostPosted: Thu Jun 07, 2007 8:38 am    Post subject: Reply with quote

True enough Marty - but I was looking at Keith's hypothesis about directly solving r1c9.
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Mogulmeister



Joined: 03 May 2007
Posts: 695

PostPosted: Thu Jun 07, 2007 2:27 pm    Post subject: Reply with quote

I overlooked your XY wing when I did my original first attempt.
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Marty R.



Joined: 12 Feb 2006
Posts: 5164
Location: Rochester, NY, USA

PostPosted: Thu Jun 07, 2007 3:42 pm    Post subject: Reply with quote

Mogulmeister wrote:
True enough Marty - but I was looking at Keith's hypothesis about directly solving r1c9.


I'm not a good thinker like some of you guys. I'm a mechanic and take the path of least resistance.
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keith



Joined: 19 Sep 2005
Posts: 3178
Location: near Detroit, Michigan, USA

PostPosted: Sat Jun 09, 2007 1:53 pm    Post subject: Reply with quote

I did not decide to focus on R1C9 when I first solved it. I noticed that R1C9 could be solved by two forks (skyscrapers), and the puzzle falls apart.

Keith
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