Regina Bittencourt Canvas presented at the 2018 JMM Conference in San Diego and re-created by me into glass and further delineating the boundaries by using the fine line technique. 

 

This piece melds 3 math theorems:  

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1. The four-color Map Theorem as described above, eg, any map in a plane can be created using four colors, so that regions sharing a common boundary do not share the same color.
    

2. The 21 squares are not of different sizes which makes it imperfect
    

3. It is simple because no subset of the square forms a rectangle or another square.