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keith · Posted: Mon Jun 04, 2007 5:13 am Post subject: MM Diabolical June 3, 2007

Did you try this one?

Mogulmeister · Joined: 03 May 2007 Posts: 1151

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

Mogulmeister · Joined: 03 May 2007 Posts: 1151

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.

Marty R. · Posted: Thu Jun 07, 2007 4:34 am Post subject:

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

Mogulmeister · Joined: 03 May 2007 Posts: 1151

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

Mogulmeister · Joined: 03 May 2007 Posts: 1151

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

Marty R. · Posted: Thu Jun 07, 2007 3:42 pm Post subject:

keith · Posted: Sat Jun 09, 2007 1:53 pm Post subject:

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