Question regarding an apparent unique rectangle

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Question regarding an apparent unique rectangle

Postby groston » Wed Sep 05, 2012 4:36 am

All,

My first post to this forum. I am an advanced beginner - I play on my Android phone, using the app Enjoy Sudoku. I play at the 'Difficult' level and usually finish the puzzles in around three minutes

I ran into a situation today that I do not understand and was hoping that some one could enlighten me. The image below shows the puzzle mid-way through:

Image

To my eye, the four squares shaded green appear to be a unique rectangle, thus one needs to avoid a 'deadly pattern'. This suggests that one of the square on the right side of the rectangle needs to be a 1, making the square highlighted yellow-green an 8 - because if it were a 1, then the 'deadly pattern' emerges. I tried this approach, and it was wrong. To solve the puzzle, one needs to see the 'other' unique rectangle (shaded pink) and assign the value 2 to the top-left square of that rectangle. When following this route, the following is how the board looks just prior to being completed:

Image

This pattern seems to go against the notion of avoiding a 'deadly pattern'. Would someone kindly explain why this doesn't violate that principal, and perhaps, suggest what I should be alert to in the future should this arise again.

p.s. It should be obvious that I am not well-versed in Sudoku terminology, so please consider that when you reply.

Many thanks!

p.s. Based on my viewing of a few topics in this section of the forum, many of you seem to be heavy-duty mathematicians. I am just an engineer, so please show some mercy.
groston
 
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Re: Question regarding an apparent unique rectangle

Postby daj95376 » Wed Sep 05, 2012 5:11 am

groston wrote:This pattern seems to go against the notion of avoiding a 'deadly pattern'. Would someone kindly explain why this doesn't violate that principal, and perhaps, suggest what I should be alert to in the future should this arise again.

The four cells of a Unique Rectangle reside in two rows, two columns, and two boxes. Your green cells reside in four boxes, but your pink cells do form a legitimate UR Type 1.
daj95376
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Re: Question regarding an apparent unique rectangle

Postby groston » Wed Sep 05, 2012 12:57 pm

Thanks for the reply!
groston
 
Posts: 2
Joined: 05 September 2012


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