Decidability Problems for Self-induced Systems Generated by a Substitution

Timo Jolivet (1) , Anne Siegel (2)

1 IMT - Institut de Mathématiques de Toulouse UMR5219
2 Dyliss - Dynamics, Logics and Inference for biological Systems and Sequences

In this talk we will survey several decidability and undecidability results on topological properties of self-affine or self-similar fractal tiles. Such tiles are obtained as fixed point of set equations governed by a graph. The study of their topological properties is known to be complex in general: we will illustrate this by undecidability results on tiles generated by multitape automata. In contrast, the class of self affine tiles called Rauzy fractals is particularly interesting. Such fractals provide geometrical representations of self-induced mathematical processes. They are associated to one-dimensional combinatorial substitutions (or iterated morphisms). They are somehow ubiquitous as self-replication processes appear naturally in several fields of mathematics. We will survey the main decidable topological properties of these specific Rauzy fractals and detail how the arithmetic properties yields by the combinatorial substitution underlying the fractal construction make these properties decidable. We will end up this talk by discussing new questions arising in relation with continued fraction algorithm and fractal tiles generated by S-adic expansion systems.

Domaines: Informatique [cs]; Complexité [cs.CC]; Bio-informatique [q-bio.QM]

Timo Jolivet, Anne Siegel. Decidability Problems for Self-induced Systems Generated by a Substitution. MCU 2015 : Machines, Computation and Universality, 2015, Famagusta, Cyprus. ⟨10.1007/978-3-319-23111-2⟩. ⟨hal-01196152⟩