Axiomatizing Rectangular Grids with no Extra Non-unary Relations

Autor: Eryk Kopczynski
Rok vydání: 2020
Předmět:
Zdroj: Fundamenta Informaticae. 176:129-138
ISSN: 1875-8681
0169-2968
DOI: 10.3233/fi-2020-1966
Popis: We construct a formula $\phi$ which axiomatizes non-narrow rectangular grids without using any binary relations other than the grid neighborship relations. As a corollary, we prove that a set $A \subseteq \mathbb{N}$ is a spectrum of a formula which has only planar models if numbers $n \in A$ can be recognized by a non-deterministic Turing machine (or a one-dimensional cellular automaton) in time $t(n)$ and space $s(n)$, where $t(n)s(n) \leq n$ and $t(n),s(n) = \Omega(\log(n))$.
Comment: 9 pages, 1 figure
Databáze: OpenAIRE