A physically universal Turing machine
: Salo Ville, Törmä Ilkka
Publisher: Academic Press
: 2023
: Journal of Computer and System Sciences
: J. Comput. System Sci.
: 132
: 16
: 44
: 0022-0000
DOI: https://doi.org/10.1016/j.jcss.2022.08.003
: https://doi.org/10.1016/j.jcss.2022.08.003
: https://research.utu.fi/converis/portal/detail/Publication/177553931
We construct a two-dimensional Turing machine that is physically universal in both the moving tape and moving head model. In particular, it is mixing of all finite orders in both models. We also provide a variant that is physically universal in the moving tape model, but not in the moving head model.