Kernekoncepter
Turing complete dynamical systems exhibit positive topological entropy under suitable conditions, indicating chaotic behavior.
Resumé
The article explores the relationship between Turing completeness and topological entropy of dynamical systems. It first proves that a natural class of Turing machines, called regular Turing machines, have positive topological entropy. This implies that any Turing complete dynamics with a continuous encoding that simulates a universal machine in this class is also chaotic, exhibiting positive topological entropy.
The key results are:
Theorem 1 shows that any regular Turing machine has positive topological entropy.
Corollary 1 states that the Turing complete C^∞ area-preserving diffeomorphism of the disk constructed in prior work has positive topological entropy whenever the simulated universal Turing machine is regular.
The technique used to construct Turing complete area-preserving diffeomorphisms also yields the construction of Turing complete stationary Euler flows on 3D manifolds. Corollary 4 shows that these Euler flows have positive topological entropy if the simulated Turing machine is regular.
The article also discusses the notion of universal Turing machines and provides examples of regular universal Turing machines. It poses open questions about whether all universal Turing machines have positive topological entropy, and whether there exist universal Turing machines that are not regular.