Reptiles are known for polyominoes, polyiamonds, polyaboloes, and other polyforms.
Few polyforms of any kind form reptiles. A bireptile is a figure of which copies can be joined to form two joined, equally enlarged copies of the original figure.
Any figure with a reptiling trivially has a bireptiling, but not every figure with a bireptiling has a reptiling. That is, bireptiles are more common than reptiles.
Below I show minimal known bireptilings for various polyiamonds.
Yoshiaki Araki has found that the J pentiamond can form a bireptile at any scale that is a multiple of 5. Click here to see his first few cases.
Click here for a bireptile at scale 4.
Click here for ten bireptiles at scale 5.
The J pentiamond also has bireptilings at scales 6, 7, and 8.
Last revised 2022-12-07.