The finiteness problem for automaton groups and semigroups has been widely studied, several partial positive results are known. However we prove that, in the most general case, the problem is undecidable. We study the case of automaton semigroups. Given a NW-deterministic Wang tile set, we construct a Mealy automaton, such that the plane admits a valid Wang tiling if and only if the Mealy autom...

Groups and semigroups generated by Mealy automata were formally introduced in the early sixties. They revealed their full potential over the years, by contributing to important conjectures in group theory. In the current chapter, we intend to provide various combinatorial and dynamical tools to tackle some decision problems all related to some extent to the growth of automaton (semi)groups. In ...

Self-assembly, the process by which objects autonomously come together to form complex structures, is omnipresent in the physical world. Recent experiments in self-assembly demonstrate its potential for the parallel creation of a large number of nanostructures, including possibly computers. A systematic study of self-assembly as a mathematical process has been initiated by L. Adleman and E. Win...

In this article we give a new proof of the undecidability of the periodic domino problem. The main difference with the previous proofs is that this one does not start from a proof of the undecidability of the (general) domino problem but only from the existence of an aperiodic tileset. The formalism of Wang tiles was introduced in [Wan61] to study decision procedures for the ∀∃∀ fragment of the...

This work reports on some useful applications of the tile model to the speciication and execution of CCS-like process calculi. This activity is part of our ongoing research on the relation between tile logic and rewriting logic. 1 Overview Tile Logic 1;2 is a framework for modular descriptions of the dynamic evolution of concurrent systems, extending rewriting logic 3;4 (in the non-conditional ...

We study the minimal complexity of tilings of a plane with a given tile set. We note that any tile set admits either no tiling or some tiling with O(n) Kolmogorov complexity of its (n× n)squares. We construct tile sets for which this bound is tight: all (n × n)-squares in all tilings have complexity Ω(n). This adds a quantitative angle to classical results on non-recursivity of tilings – that w...