On the number of return words in infinite words with complexity 2n+1

In this article, we count the number of return words in some infinite words with complexity 2n+1. We also consider some infinite words given by codings of rotation and interval exchange transformations on k intervals. We prove that the number of return words over a given word w for these infinite words is exactly k.Comment: see also http://liafa.jussieu.fr/~vuillon/articles.htm

Coding rotations on intervals

We show that the coding of rotation by $\alpha$ on $m$ intervals with rationally independent lengths can be recoded over $m$ Sturmian words of angle $\alpha.$ More precisely, for a given $m$ an universal automaton is constructed such that the edge indexed by the vector of values of the $i$th letter on each Sturmian word gives the value of the $i$th letter of the coding of rotation.Comment: LIAFA repor

Combinatoire des motifs d'une suite sturmienne bidimensionnelle

RésuméNous étudions une généralisation des suites sturmiennes en construisant une “surface plissée”, donnée par l'approximation d'un plan par trois sortes de faces carrées orientées suivant les trois plans de coordonnées. À cette surface, on associe par projection un pavage du plan par trois sortes de losanges. On définit sur ce pavage une fonction de complexité en comptant le nombre de motifs distincts d'une fenêtre de taille donnée. Nous donnons, en étudiant les prolongements des motifs, la forme explicite de cette fonction dans le cas d'une fenêtre triangulaire et d'une fenêtre en forme de parallélogramme.AbstractWe study a generalization of sturmian sequences by constructing a “stepped surface”, given by a plane approximation with three kinds of square faces oriented according to the three coordinate planes. With a projection operation, we build a tiling of the plane by three kinds of diamonds. We define in this tiling a complexity function by counting the number of patterns in a given height window. We give the explicit form of this function in the case of triangular windows and parallelogram windows

Some special solutions to the Hyperbolic NLS equation

The Hyperbolic Nonlinear Schrodinger equation (HypNLS) arises as a model for the dynamics of three-dimensional narrowband deep water gravity waves. In this study, the Petviashvili method is exploited to numerically compute bi-periodic time-harmonic solutions of the HypNLS equation. In physical space they represent non-localized standing waves. Non-trivial spatial patterns are revealed and an attempt is made to describe them using symbolic dynamics and the language of substitutions. Finally, the dynamics of a slightly perturbed standing wave is numerically investigated by means a highly acccurate Fourier solver.Comment: 33 pages, 10 figures, 70 references. Other author's papers can be found at http://www.denys-dutykh.com

Non lattice periodic tilings of R3 by single polycubes

International audienceIn this paper, we study a class of polycubes that tile the space by translation in a non lattice periodic way. More precisely, we construct a family of tiles indexed by integers with the property that Tk is a tile having k ≥ 2 has anisohedral number. That is k copies of Tk are assembled by translation in order to form a metatile. We prove that this metatile is lattice periodic while Tk is not a lattice periodic tile

2L-CONVEX POLYOMINOES: GEOMETRICAL ASPECTS

International audienceA polyomino P is called 2L-convex if for every two cells there exists a monotone path included in P with at most two changes of direction. This paper studies the geometrical aspects of a sub-class of 2L-convex polyominoes called I0,0 and states a characterization of 2L it in terms of monotone paths. In a second part, four geometries are introduced and the tomographical point of view is investigated using the switching components (that is, the elements of this sub-class that have the same projections). Finally, some unicity results are given for the reconstruction of these polyominoes according to their projections

Non lattice periodic tilings of R3 by single polycubes

International audienceIn this paper, we study a class of polycubes that tile the space by translation in a non lattice periodic way. More precisely, we construct a family of tiles indexed by integers with the property that Tk is a tile having k ≥ 2 has anisohedral number. That is k copies of Tk are assembled by translation in order to form a metatile. We prove that this metatile is lattice periodic while Tk is not a lattice periodic tile

Geometric Palindromic Closure

http://www.boku.ac.at/MATH/udt/vol07/no2/06DomVuillon13-12.pdfInternational audienceWe define, through a set of symmetries, an incremental construction of geometric objects in Z^d. This construction is directed by a word over the alphabet {1,...,d}. These objects are composed of d disjoint components linked by the origin and enjoy the nice property that each component has a central symmetry as well as the global object. This construction may be seen as a geometric palindromic closure. Among other objects, we get a 3 dimensional version of the Rauzy fractal. For the dimension 2, we show that our construction codes the standard discrete lines and is equivalent to the well known palindromic closure in combinatorics on words

How many faces can polycubes of lattice tilings by translation of R3 have?

International audienceWe construct a class of polycubes that tile the space by translation in a lattice- periodic way and show that for this class the number of surrounding tiles cannot be bounded. The first construction is based on polycubes with an L-shape but with many distinct tilings of the space. Nevertheless, we are able to construct a class of more complicated polycubes such that each polycube tiles the space in a unique way and such that the number of faces is 4k + 8 where 2k + 1 is the volume of the polycube. This shows that the number of tiles that surround the surface of a space-filler cannot be bounded