Freeness conjecture for self-projective sets

Let b[?mASL(2,R)b[0mb[?m\mathcal{A}\subset\mathrm{SL}(2,\mathbb{R})b[0m be a finite set of matrices, let b[?mGAb[0mb[?mG_{\mathcal{A}}b[0m be the semigroup it generates, and let b[?mΛAb[0mb[?m\Lambda_{\mathcal{A}}b[0m be its limit set. Let b[?msAb[0mb[?ms_{\mathcal{A}}b[0m denote the critical exponent associated with the zeta function of b[?mAb[0mb[?m\mathcal{A}b[0m.

Freeness conjecture. If b[?mGAb[0mb[?mG_{\mathcal{A}}b[0m is a free semigroup and b[?mΛAb[0mb[?m\Lambda_{\mathcal{A}}b[0m is non-empty and not a singleton, then

dimHΛA=min{1,sA}.\dim_{\textup{H}}\Lambda_{\mathcal{A}}=\min\{1,s_{\mathcal{A}}\}.

This generalizes the exact-overlaps conjecture for self-similar sets to self-projective sets. It predicts that freeness is sufficient for the critical-exponent formula to give the Hausdorff dimension, beyond the special cases established earlier in the paper.

Sources & referencesView supporting material

Primary source

Argyrios Christodoulou and Natalia Jurga, “Self-projective sets”, arXiv:2402.12229 (2024).

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