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.
