Piecewise-affine factor-map conjecture for Lorenz-attractor perturbations

From papers

Let R\mathcal{R} be the collection of all maps F:[0,1][0,1]\mathcal{F}:[0,1]\to[0,1] that serve as factor maps for first-return maps ψv:RWR\psi_v:R\setminus W\to R of the Lorenz attractor, not necessarily only for parameters vPv\in P. For a map in R\mathcal{R}, use a partition

0=c0<c1<<cn<cn+1=10=c_0<c_1<\ldots<c_n<c_{n+1}=1

and let I\mathcal{I} be the invariant set in [0,1]{c1,,cn}[0,1]\setminus\{c_1,\ldots,c_n\}. Piecewise-affine factor-map conjecture. Every FR\mathcal{F}\in\mathcal{R} satisfies: (i) F\mathcal{F} is piecewise discontinuous, orientation-preserving and affine on each (ck,ck+1)(c_k,c_{k+1}), with a jump discontinuity at every cic_i; (ii) whenever ψv\psi_v is semi-conjugated to F\mathcal{F}, there is an invariant set IvI_v for ψv\psi_v and a continuous surjection π:IvI\pi:I_v\to\mathcal{I} such that

πψv=Fπ;\pi\circ\psi_v=\mathcal{F}\circ\pi;

(iii) if xIx\in\mathcal{I} has minimal period nn under F\mathcal{F}, then π1(x)\pi^{-1}(x) contains a periodic orbit of minimal period nn for ψv\psi_v. The conjecture is motivated by numerical Lorenz systems with heteroclinic knots other than trefoils, for which a more general piecewise-continuous model may replace the beta-transformations; no resolution is supplied.

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Sources & referencesView supporting material

Primary source

Łukasz Cholewa and Eran Igra, “Kneading the Lorenz attractor”, arXiv:2511.02568 (2025).

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