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Marty R. · Posted: Sat Jun 10, 2006 6:12 pm Post subject: Unique parallelograms?

I have shown only the numbers in one stack which I believe to be relevant to my question.

Do I have to set the upper left cell to "6"? If it is not "6", then it looks like the "deadly pattern." I have seen deadly patterns discussed only within the context of Unique Rectangles; however, should not the same principles apply to any four-cornered figure in two boxes, such as parallelograms and trapezoids?

Ruud · Joined: 18 Jan 2006 Posts: 31

Hi Marty,

Unique Rectangles exist because they share exactly 2 rows, 2 columns and 2 boxes.

You parallelogram shares 2 boxes, 4 rows and 2 columns. These 2 extra rows give ample opportunity to avoid 2 solutions.

There is a shape that can be used for uniqueness, which is the Unique Swordfish:

Marty R. · Posted: Sat Jun 10, 2006 9:12 pm Post subject:

Thanks Ruud, you saved me from a heap of frustration, even though I'm not seeing why the parallelogram wouldn't constitute the deadly pattern. Question

keith · Posted: Sat Jun 10, 2006 10:43 pm Post subject: Parallelograms

Marty,

Let's try this. Assume this is a fragment of a solution:

Marty R. · Posted: Sun Jun 11, 2006 12:15 am Post subject:

Keith, thank you. I was going to tell you I still didn't understand, but after staring more, I think I get it. I was sure those 38s were interchangeable, which they appear to be, but I was not considering what was outside the stack. So I guess they're not interchangeable and I'm not going to now suggest that the technique name be changed to "Unique Quadrilaterals." Laughing