Squarematch - Special Solutions

Symmetric Solutions

For the 5x5, the solution pictured here is the "most symmetric".

With 3 colors and several asymmetric pieces which do not have mirror images, perfect symmetry is not possible, but there is a great deal of symmetry about the central vertical column(s).

Blue is symmetric to itself, and white and gray are symmetric to each other. If you look at it as 10 rows (and columns) of colored squares, the symmetry holds for the first nine rows, but it breaks down on the 10th row. In fact, only the last two pieces at the lower right corner break the symmetry, since there is not piece to pair with the checkerboard at the lower left.

These figures show maximally-symmetric solutions for 4x6 and 3x8. A few red lines have been added to emphasize the symmetry visually.

Here, blue and white are symmetric to each other (mostly) and green with itself.

For the 4x6, only the 4 blue squares in the middle of the right-hand green "P" are out of symmetry.

For the 3x8, there are just 8 squares out of symmetry. They can be seen in green along a line between the two yellow dots on the edge of the figure, from the middle of the left hand side to just right of center on the bottom.

Two-way solutions

The 3x8 and 4x6 can also be solved "simultaneously" in 1527 different ways by finding two 3x4 rectangles which match up along both a 3- and 4-edge, as shown in this figure. These form 1493 different 3x8's and 1416 different 4x6's.

In this case, the left and right edges of the 3x8 solution match up, so the upper 4x3 block could be placed on either the left or the right, yielding two 3x8s from this 4x6.


Furthermore, when two opposite edges match like that, each column of 3 tiles can be moved from one end to the other, yielding 8 different solutions. Such a solution might be called cylindrical, since it could be wrapped around a cylinder, with edgematching all the way around.

There are 1536 3x8 cylinders and 180 4x6 cylinders, one of which is shown here.
This 4x6 cylinder can be "unfolded" (at either end) to become a 3x8 cylinder!


Thanks to Jacques Haubrich for providing the idea to look at the 3x8, cylinders, and the transforms between 3x8 and 4x6.