Graph subshifts
Provides foundational theory for graph subshifts, linking symbolic dynamics and group theory, with implications for decidability in graph-based systems.
The paper introduces graph subshifts of finite type, extending symbolic dynamics and combinatorial group theory, and proves that subshifts containing only infinite graphs are either aperiodic or lack residual finiteness, leading to undecidability results.
We propose a definition of graph subshifts of finite type that can be seen as extending both the notions of subshifts of finite type from classical symbolic dynamics and finitely presented groups from combinatorial group theory. These are sets of graphs that are defined by forbidding finitely many local patterns. In this paper, we focus on the question whether such local conditions can enforce a specific support graph, and thus relate the model to classical symbolic dynamics. We prove that the subshifts that contain only infinite graphs are either aperiodic, or feature no residual finiteness of their period group, yielding non-trivial examples as well as two natural undecidability theorems.