Denjoy examples of class $C^1$ with affine dynamics outside the invariant Cantor set

arXiv:2607.11748 2026 Dynamics 1 ideas extracted · analyzed Aug 30, 2026

What the math gives to ML

The paper gives a constructive Denjoy blow-up mechanism: an irrational circle rotation is lifted by replacing each orbit point with an interval of length lₙ, with Σₙ lₙ < ∞, producing an invariant zero-measure exceptional set and dynamics that are affine on every complementary interval. The transferable asset is an explicit semiconjugacy from simple neutral phase dynamics to piecewise-affine transport whose local expansion is controlled by adjacent interval lengths. A neural analogue is a phase-indexed recurrent memory whose cells transport hidden states with analytically specified gains. The sharp prediction is that the product of local transport slopes telescopes exactly to an endpoint-width ratio, allowing long-horizon memory distortion to be designed and monitored.

Ideas from this paper

Unverified 2026

Denjoy Affine-Orbit Memory

Add a bounded phase variable and a bank of local affine transport maps to an RNN or state-space model. The phase follows an irrational rotation, while the hidden state is transported through cells whose widths determine local gains, giving a controllable memory mechanism with analytically known distortion rather than an unconstrained recurrent Jacobian.

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Paper: Denjoy examples of class $C^1$ with affine dynamics outside the invariant Cantor set arXiv:2607.11748