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

[quote]XZ-XY-YZ=YZ=YZ[quote]

The xy-wing I used was the <58> pivot and <35> <38> pincers shown below. I see the XZ-XY-YZ=YZ=YZ sequence here - but isn't the =YZ bit (removing the <3> in R7) just the expected outcome of the wing technique. And once this <3> is removed, there's simply a naked <8> in Box 3.
I guess what I'm saying is: does the "=YZ=YZ" need a special name (pincer colouring) -when it's really just back to basics - or as we used to say in the UK - "it all comes out in the wash".

keith · Posted: Sun Dec 16, 2007 10:05 pm Post subject:

[quote="cgordon"][quote]XZ-XY-YZ=YZ=YZ

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

Keith:
Yeah yeah - now I see it. You are sticking the "=YZ=YZ" bit in the middle of the "XZ-XY-YZ" bit - not at the end. What troubles me is that two prominent regulars agreed that this method was fun.
Sophisticates are not usually into hard work and unnecessary labouring.

nataraj · Posted: Mon Dec 17, 2007 11:03 pm Post subject:

Craig,

rest assured, I am not "into hard work and unnecessary labouring" (but then again I would not call myself a sophisticate ... Laughing

)

On the contrary, I am quite lazy. So when I've gone to all that trouble and finally found an xy-wing, I try and check all other possibilities, even when at first glance the xy-wing doesn't eliminate anything.

It is like a salvage operation. Or, you could say, it is two shots for the price of one. Amazingly often, the extension of such a wing, be it at either end or in the middle, yields a useful result. In my experience, it is MUCH easier to spot xy-wings that way.

Long live the flightless bird!

keith · Posted: Mon Dec 17, 2007 11:39 pm Post subject:

Nataraj,

Great picture!

(All: The inside joke here is that some of us are naming these "useless" wings that make no direct eliminations as "flightless" wings.)

Nataraj is correct: If you are looking for XY-wings and find one that does not make an elimination, look to see if you can extend it by coloring.

Or, if you have a chain XY=XY=XY, see if it can be the pivot of an extended XY-wing.

Last night I was looking at the discussions from a year or two ago. It is incredible how the human-recognizable pencil and paper techniques have evolved and improved.

Keith