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Smooth Fractal Trees: Analytic Generators and Discrete Equivalence

Henk Mulder

TL;DR

The paper addresses the problem of representing tree-based fractals with smooth dynamics by introducing analytic generator trees, where geometry is obtained via projection of internal generator trajectories. The main approach decouples branching structure (via explicit branch events and state inheritance) from local geometric realization, enabling smooth interpolation along edges. The two key contributions are a combinatorial universality theorem, which shows any discrete tree specification (e.g., IFS or L-systems) can be compiled into an analytic generator tree whose discrete scaffold matches at every finite depth, and a canopy-set equivalence theorem, which proves the canopy set of the analytic construction coincides with the discrete attractor under standard contractive assumptions. Together, these results demonstrate that global fractal structure is governed by recursive branching and contraction rather than local non-differentiability, offering a smooth, differential framework that preserves both finite combinatorial structure and asymptotic geometry. The framework is currently scoped to one-dimensional generator domains and curve realizations, but it opens avenues for reactive generators and higher-dimensional extensions while enabling differential tools to analyze fractal trees.

Abstract

We introduce a framework for constructing fractal trees via analytic generator fields, replacing discrete affine transformations and symbolic rewriting rules by the integration of smooth vector fields in an internal state space. In this setting, geometric curves are obtained as projections of generator trajectories, and branching is implemented as a primitive operation through exact inheritance of generator state. At every finite depth, the resulting structure is a finite union of analytic curve segments that is smooth across branch events. Two structural results relate this generator-driven construction to classical discrete models of tree-based fractals. First, a combinatorial universality theorem shows that any discrete tree specification, including those arising from iterated function systems and L-systems, can be compiled into an analytic generator tree whose induced discrete scaffold is isomorphic at every finite depth. Second, under standard contractive assumptions, a canopy set equivalence theorem establishes that the accumulation set of analytic branch endpoints coincides with the attractor of the corresponding discrete construction. These results separate local geometric regularity from global fractal complexity, showing that fractality is determined by recursive branching and scaling rather than by local non-smoothness. The framework provides a smooth representation of tree-based fractals that preserves both their finite combinatorial structure and their asymptotic limit geometry.

Smooth Fractal Trees: Analytic Generators and Discrete Equivalence

TL;DR

The paper addresses the problem of representing tree-based fractals with smooth dynamics by introducing analytic generator trees, where geometry is obtained via projection of internal generator trajectories. The main approach decouples branching structure (via explicit branch events and state inheritance) from local geometric realization, enabling smooth interpolation along edges. The two key contributions are a combinatorial universality theorem, which shows any discrete tree specification (e.g., IFS or L-systems) can be compiled into an analytic generator tree whose discrete scaffold matches at every finite depth, and a canopy-set equivalence theorem, which proves the canopy set of the analytic construction coincides with the discrete attractor under standard contractive assumptions. Together, these results demonstrate that global fractal structure is governed by recursive branching and contraction rather than local non-differentiability, offering a smooth, differential framework that preserves both finite combinatorial structure and asymptotic geometry. The framework is currently scoped to one-dimensional generator domains and curve realizations, but it opens avenues for reactive generators and higher-dimensional extensions while enabling differential tools to analyze fractal trees.

Abstract

We introduce a framework for constructing fractal trees via analytic generator fields, replacing discrete affine transformations and symbolic rewriting rules by the integration of smooth vector fields in an internal state space. In this setting, geometric curves are obtained as projections of generator trajectories, and branching is implemented as a primitive operation through exact inheritance of generator state. At every finite depth, the resulting structure is a finite union of analytic curve segments that is smooth across branch events. Two structural results relate this generator-driven construction to classical discrete models of tree-based fractals. First, a combinatorial universality theorem shows that any discrete tree specification, including those arising from iterated function systems and L-systems, can be compiled into an analytic generator tree whose induced discrete scaffold is isomorphic at every finite depth. Second, under standard contractive assumptions, a canopy set equivalence theorem establishes that the accumulation set of analytic branch endpoints coincides with the attractor of the corresponding discrete construction. These results separate local geometric regularity from global fractal complexity, showing that fractality is determined by recursive branching and scaling rather than by local non-smoothness. The framework provides a smooth representation of tree-based fractals that preserves both their finite combinatorial structure and their asymptotic limit geometry.
Paper Structure (43 sections, 10 theorems, 44 equations, 3 figures)

This paper contains 43 sections, 10 theorems, 44 equations, 3 figures.

Key Result

Proposition 1

Let $V : J \times \mathbb{R}^n \to \mathbb{R}^n$ be an analytic (or $C^k$, $k \ge 1$) generator field, and let $(s_0, X_0) \in J \times \mathbb{R}^n$ be an initial condition. Then there exists $\varepsilon > 0$ and a unique solution to the ordinary differential equation eq:generator_ode satisfying $X(s_0) = X_0$ (cf. Picard--Lindelöf).

Figures (3)

  • Figure 1: Analytic fractal tree constructed via generator-driven dynamics with exponential radial decay $\rho(s) = A^s$ ($A = 0.88$) and linear angular modulation $\theta(s) = \theta_0 \pm \Omega s$ ($\Omega = \pi/10$). Binary branching is implemented through exact state inheritance at fixed generator phase $s_b$, with left and right children assigned opposite curvature signs ($\sigma_1 = +1$, $\sigma_2 = -1$). All branches are analytic curves; fractality emerges from recursive branching structure rather than local geometric irregularity.
  • Figure 2: Analytic generator tree (solid curves) and its induced discrete scaffold (dotted segments). Branchpoints (filled circles) are realized directly by the generator construction. The discrete scaffold connects these branchpoints with straight chords, preserving combinatorial structure and endpoint locations.
  • Figure 3: Geometric extraction of discrete IFS parameters from a smooth analytic generator tree. Scaffold nodes (open circles) are obtained by tangent intersection rather than direct construction. The recovered contraction ratios $\hat{\lambda}_a = A$ and turning angles $|\hat{\theta}_a| = \omega$ confirm that discrete similarity data emerges from smooth generator geometry, illustrating recovery of discrete similarity data, consistent with Theorem 2.

Theorems & Definitions (27)

  • Definition 1: Analytic Generator Field
  • Proposition 1: Local Realizability
  • Remark 1: Role of Analyticity.
  • Definition 2: Branch Event
  • Definition 3: No-Offset Branching Constraint
  • Definition 4: Generator Inheritance
  • Proposition 2: Regularity Across Branch Events
  • Remark 2: Local reset versus global generator progress
  • Definition 5: Generator Tree
  • Proposition 3: Finite-Stage Smoothness
  • ...and 17 more