Message #2978

From: andreyastrelin@yahoo.com
Subject: Re: [MC4D] RE: MagicTile Solving
Date: Mon, 10 Mar 2014 00:48:28 -0700

Melinda,
the question about number of vertices of the puzzle where two faces may have more than one common vertex is not easy. For example, look at these two puzzles:
https://www.dropbox.com/s/0epazx6q6crnvh1/%7B4%2C4%7D%204C.xml https://www.dropbox.com/s/0epazx6q6crnvh1/%7B4%2C4%7D%204C.xml
https://www.dropbox.com/s/w5hi3lep8hu3msi/%7B4%2C4%7D%204C_B.xml https://www.dropbox.com/s/w5hi3lep8hu3msi/%7B4%2C4%7D%204C_B.xml
They have the same coloring pattern (it’s 2x2 torus) and the same set of face-centered puzzles. First puzzle has 4 faces, 8 edges and 4 vertices - as it should have. Second puzzle contains one extra element in the symmetry group (central symmetry), so it has 4 faces, 4 edges and 2 vertices. I’ve tried to reduce it to 1 vertex, but still can’t do it with the current engine. Actually it’s very special case that can work only with digonal faces, so i’m not surprised…

Andrey