Forcing among exact patterns of triods
Sourav Bhattacharya
TL;DR
The article provides a complete characterization of topologically exact patterns on triods by introducing rotation-based classifications (slow, fast, ternary) and proving that exactness corresponds to the absence of block structure in patterns. It develops a robust framework of blocks, loops, and $P$-linear maps to analyze forcing among patterns, and derives three explicit, perturbation-stable orderings on natural numbers that capture forcing within each rotation-number class. These results extend Blokh–Misiurewicz-style rotation theory to triods, offering precise predictions for coexistence of exact patterns and advancing the understanding of combinatorial dynamics on branched one-dimensional spaces.
Abstract
We obtain a complete characterization of \emph{topologically exact patterns} on \emph{triods}. Based on their \emph{rotation number} $ρ$, these \emph{exact patterns} are grouped into three classes: \emph{slow} ($ρ< \frac{1}{3}$), \emph{fast} ($ρ> \frac{1}{3}$) and \emph{ternary} ($ρ= \frac{1}{3}$). For each category, we derive a \emph{linear ordering} of the set of natural numbers, $\mathbb{N}$ that captures \emph{forcing} between the \emph{patterns}. We also show that each of these orderings is \emph{stable} under perturbations.
