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alanr555 · Posted: Tue Dec 11, 2007 3:54 am Post subject:

Yes.
I agree with Storm-Norm's result.
I got stuck at the same point.

Apologies for the duplicate topic - composing in the same timeframe.
Perhaps SamGJ can merge the topics for us.

storm_norm · Joined: 18 Oct 2007 Posts: 1741

hi alanr555,

my grid is how it would look after basic moves such as naked pairs, box line interactions etc.

however, I have not given a solution because it is still early, I don't want to ruin it yet. lol

Norm

Marty R. · Posted: Tue Dec 11, 2007 6:19 am Post subject: Re: Dec 11th VH

storm_norm · Joined: 18 Oct 2007 Posts: 1741

nataraj · Posted: Tue Dec 11, 2007 7:07 am Post subject:

aside from basic moves...

xwing on 6 (c34), later
xwing on 7 (c67)

but some eliminations took me a long time to see.

BTW how come you guys got the puzzle early today. Have the timezones benn mixed up? Smile

Johan · Joined: 25 Jun 2007 Posts: 206 Location: Bornem Belgium

A [27-127-12] XYZ-wing and a swordfish* on <7> in C167. The x-wing mentioned by Norm could have saved me a lot of time, but I missed that one completely.

Victor · Joined: 29 Sep 2005 Posts: 207 Location: NI

Nice 'rich' puzzle in terms of basic moves. The X-Wing in 7s in rows 6 & 8 pretty well finishes it. (Took me a while also - searching for XY- or XYZ - wings.)

Asellus · Posted: Tue Dec 11, 2007 12:19 pm Post subject:

A comment on the elimination of those <2>s in r13c4...

The W-Wing alone eliminates both, one directly and one by transporting the pincer <2> in r3c1 to r1c8 via the strong link in Box 3.

And, the XYZ Wing with pivot r3c5 also eliminates both, one directly and one by transporting the same <2> to the same cell in the same manner.

Victor · Joined: 29 Sep 2005 Posts: 207 Location: NI

Sorry, forgot what I'd done & wrote carelessly - the X-wing is in C 6 & 7

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

I found a quad <3458> in Box 4 and then just used two X-wings:
for <3> R17: then <7> C67.
I'm not actually convinced that X-wings should be a VH technique. I used them even before I'd heard about wings - they are so obvious. In fact I got totally stuck with yesterday's Hard puzzle (Dec 10) and am sure it could only be solved with a simple x-wing. But I may be wrong - I was wrong once before (maybe twice).

alanr555 · Posted: Tue Dec 11, 2007 2:34 pm Post subject:

Looking through the comments made so far, I am amazed at
the breadth of techniques posited.

Storm-Norm provided the essential clue. The resolution boils
down to three stages

a) All the Mandatory Pairs preliminary work.
This gives the grid posted by Storm-Norm at the head of this topic.

b) Recognition of a simple rectangle in cols6,7 rows 5,9.

c) Full resolution using simple (sole candidate) techniques.

As always, the challenge is to identify the crucial factor. My thanks
go to Storm-Norm for doing this for me in this case. The detail
development of my understanding of the resolution is in the other
topic relating to this puzzle.

storm_norm · Joined: 18 Oct 2007 Posts: 1741