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Clement · Posted: Thu Jul 19, 2012 11:52 pm Post subject: Jul 20 VH

After the Basics

Rocky Mozell · Joined: 28 Jul 2010 Posts: 34 Location: Boston, MA

I just used a 345 XYZ wing.

kent7618 · Joined: 15 Jun 2012 Posts: 8

458 xyz wing can also be used.

smc · Joined: 03 Aug 2012 Posts: 4

Is this really a valid puzzle? I don't how it can be, with the 2's and 4's forming a unique rectangle in B-4, B-8, and C-4, C-8. ~smc

Marty R. · Posted: Fri Aug 03, 2012 5:00 pm Post subject: Re: unique rectangle

smc · Joined: 03 Aug 2012 Posts: 4

Thanks for the welcome, Marty. Just making sure we're talking about the July 20 Very Hard puzzle. In row B, column 4, there is a 4, and in column 8, there is a 2. Then, in row C, column 4, there is a 2, and in column 8, a 4, which was a given. I had originally had 458 as the possibles for B4, but ruled out 4 because that would result in a unique rectangle. I kept hitting snags, and finally found that 4 is the correct answer for that cell. Why is this OK?

Marty R. · Posted: Sat Aug 04, 2012 12:50 am Post subject:

Smc,

Below is an example or a UR, or, more accurately, a Deadly Pattern (DP), so called because it's an invalid solution because the numbers can be interchanged, leading to two solutions to what is supposed to be a puzzle with a unique solution.

A DP cannot contain a given because there is no interchangeability. Hope this is clear enough.