Finite presentation of the subgroup G ⊂ SL2(C) generated by X=βα, Y=α^{-1}γ, Z=β^{-1}γ^{-1}
Prove that the subgroup G of SL2(C) generated by X = βα, Y = α^{-1}γ, and Z = β^{-1}γ^{-1} admits the following finite presentation (equivalently stated in two forms): either G = ⟨X, Y, Z | XXX = yXyX = yzYX = YzzX = yZxYzX = −I⟩, or equivalently G = ⟨X, Y, Z | ZxxYXXX = yZyZYYzYX = ZZxZYzXzX = I, XXX = yZxYzX = yXyX = −I⟩, where I is the 2×2 identity matrix and −I is the diagonal matrix with −1 on the diagonal.
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Conjecture. Let I be the 2 × 2 identity matrix, and −I be the 2 × 2 matrix with −1 on the diagonal. Then G has either of the following two finite presentations: {G} = {X, Y, Z | XXX = yXyX = yzYX = YzzX = yZxYzX = −I} or, equivalently {G} = {X, Y, Z | ZxxYXXX = yZyZYYzYX = ZZxZYzXzX = I, XXX = yZxYzX = yXyX = −I}.
— Stones, Bones, and Snakes: Tilability of the hexagonal grid via the double dimer model
(2509.21700 - Foster, 25 Sep 2025) in Conjecture (label finitegroup), Section 3: Tiling groups