Classification conjecture for fault-line tilings in the Jeandel–Rao shift

Let Ω4\Omega_4 be the Wang shift under consideration, let X4Ω4X_4\subset\Omega_4 be the associated subshift, and let Yi+Y_i^+ and YiY_i^- be the horizontal-shift orbit closures of the tilings yi+y_i^+ and yiy_i^- for i{0,1}i\in\{0,1\}. Write Yi2Yi+σ\overline{Y_i^-\odot^2Y_i^+}^\sigma for the corresponding shift orbit closure, and let y0,y1,y2,y3y_0,y_1,y_2,y_3 be the tilings specified in the source. Fault-line classification conjecture. Every tiling in Ω4\Omega_4 has at most one horizontal fault line; if it has one, that fault line consists of 00's or 11's, and

Ω4X4=(Y02Y0+σY12Y1+σ){y0,y1,y2,y3}σ.\Omega_4\setminus X_4=\left(\overline{Y_0^-\odot^2Y_0^+}^\sigma\cup\overline{Y_1^-\odot^2Y_1^+}^\sigma\right)\setminus\overline{\{y_0,y_1,y_2,y_3\}}^\sigma.

Here y2=ȷηω6ω7ω8ω9ω10ω11ρ(z2)y_2=\jmath\,\eta\,\omega_6\,\omega_7\,\omega_8\,\omega_9\,\omega_{10}\,\omega_{11}\,\rho(z_2) and y3=ȷηω6ω7ω8ω9ω10ω11ρ(z3)y_3=\jmath\,\eta\,\omega_6\,\omega_7\,\omega_8\,\omega_9\,\omega_{10}\,\omega_{11}\,\rho(z_3), with z2z_2 and z3z_3 as specified in the source. The statement classifies the complement of X4X_4 as fault-line tilings, apart from the indicated exceptional orbit closure; its resolution is not established by the supplied text.

Sources & referencesView supporting material

Primary source

Sébastien Labbé, “Substitutive structure of Jeandel-Rao aperiodic tilings”, arXiv:1808.07768 (2019).

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