A1 Refereed original research article in a scientific journal
An algebraic geometric approach to Nivat's conjecture
Authors: Jarkko Kari, Michal Szabados
Publisher: Elsevier Inc.
Publication year: 2020
Journal: Information and Computation
Journal name in source: Information and Computation
Volume: 271
eISSN: 1090-2651
DOI: https://doi.org/10.1016/j.ic.2019.104481
We study multidimensional configurations (infinite words) and subshifts of low pattern complexity using tools of algebraic geometry. We express the configuration as a multivariate formal power series over integers and investigate the setup when there is a non-trivial annihilating polynomial: a non-zero polynomial whose formal product with the power series is zero. Such annihilator exists, for example, if the number of distinct patterns of some finite shape D in the configuration is at most the size |D| of the shape. This is our low pattern complexity assumption. We prove that the configuration must be a sum of periodic configurations over integers, possibly with unbounded values. As a specific application of the method we obtain an asymptotic version of the well-known Nivat's conjecture: we prove that any two-dimensional, non-periodic configuration can satisfy the low pattern complexity assumption with respect to only finitely many distinct rectangular shapes D.