Non-spectrality of planar self-affine measures with three-elements digit set

The self-affine measure μM,D associated with an affine iterated function system {?d(x)=M−1(x+d)}_d∈D is uniquely determined. The problems of determining the spectrality or non-spectrality of a measure μM,D have been received much attention in recent years. One of the non-spectral problem on μM,D is to estimate the number of orthogonal exponentials in L²(μM,D) and to find them. In the present paper we show that for an expanding integer matrix M∈M₂(Z) and the three-elements digit set D given by

     

Spectrality of planar self-affine measures with two-element digit set

The iterated function system with two element digit set is the simplest case and the most important case in the study of self affine measures.The one dimensional case corresponds to the Bernoulli convolution whose spectral property is understandable.The higher dimensional analogue is not known,for which two conjectures about the spectrality and the non spectrality remain open.In the present paper,we consider the spectrality and non spectrality of planar self affine measures with two element digit set.We give a method to deal with the two dimensional case,and clarify the spectrality and non spectrality of a class of planar self affine measures.The result here provides some supportive evidence to the two related conjectures.     

Disklikeness of planar self-affine tiles

We consider the disklikeness of the planar self-affine tile generated by an integral expanding matrix and a consecutive collinear digit set . Let be the characteristic polynomial of . We show that the tile is disklike if and only if . Moreover, is a hexagonal tile for all the cases except when , in which case is a square tile. The proof depends on certain special devices to count the numbers of nodal points and neighbors of and a criterion of Bandt and Wang (2001) on disklikeness.

     

Connectedness of a class of planar self-affine tiles

We consider a class of planar self-affine tiles T that are generated by the lower triangular expanding matrices and the product-form digit sets. We give necessary and sufficient conditions for T to be connected and disk-like. Also for the disconnect case, we give a condition that enumerates the number of connected components of T.     

素数下的整自仿tiles的数字集

讨论了一维情形下有素数行列式值的整数自仿tiles,其数字集D的特征.通过比较b与p的关系得到如下结论：（i）pbD是mod p的一个完全剩余类;（ii）p｜bD=pγD0,其中γ∈N＊,D0是modp的一个完全剩余类.该结论可被推广到高维情形,加强了一些作者的结果.最后,给出与此结论相关的三个注记与例子.     

Height reducing property of polynomials and self-affine tiles

A monic polynomial \({f(x)\in {\mathbb Z}[x]}\) is said to have the height reducing property (HRP) if there exists a polynomial \({h(x)\in {\mathbb Z}[x]}\) such that

$f(x)h(x)=a_n x^n+a_{n-1}x^{n-1}+\cdots+a_1x\pm q,$

where q = f(0), |a _i | ≤ (|q| ?1), i = 1, . . . , n and a _n > 0. We show that any expanding monic polynomial f(x) has the height reducing property, improving a previous result in Kirat et al. (Discrete Comput Geom 31: 275–286, 2004) for the irreducible case. The proof relies on some techniques developed in the study of self-affine tiles. It is constructive and we formulate a simple tree structure to check for any monic polynomial f(x) to have the HRP and to find h(x). The property is used to study the connectedness of a class of self-affine tiles.

     

A class of spectral self-affine measures with four-element digit sets

The self-affine measure _μM,D${\mu }_{M,D}$ associated with an expanding matrix M∈_Mn(Z)$M\in M_n(\mathbb{Z})$ and a finite digit set D⊂Zⁿ$D\subset {\mathbb{Z}}^n$ is uniquely determined by the self-affine identity with equal weight. In this paper we construct a class of self-affine measures _μM,D${\mu }_{M,D}$ with four-element digit sets in the higher dimensions (n≥3$n\ge 3$) such that the Hilbert space L²(_μM,D)$L^2({\mu }_{M,D})$ possesses an orthogonal exponential basis. That is, _μM,D${\mu }_{M,D}$ is spectral. Such a spectral measure cannot be obtained from the condition of compatible pair. This extends the corresponding result in the plane.     

Spectrality of a class of self-affine measures with decomposable digit sets

The self-affine measure associated with an expanding matrix and a finite digit set is uniquely determined by the self-affine identity with equal weight.The spectral and non-spectral problems on the selfaffine measures have some surprising connections with a number of areas in mathematics,and have been received much attention in recent years.In the present paper,we shall determine the spectrality and non-spectrality of a class of self-affine measures with decomposable digit sets.We present a method to deal with such case,and clarify the spectrality and non-spectrality of a class of self-affine measures by applying this method.     

Spectrality of a class of self-affine measures and related digit sets

Archiv der Mathematik - This work investigates the spectrality of a self-affine measure $$mu _{M,D}$$ and the related digit set D in the case when $$|mathrm{det}(M)|=p^{alpha }$$ is a prime...     

Non-spectral problem for a class of planar self-affine measures

The self-affine measure μM,D corresponding to an expanding matrix M∈Mn(R) and a finite subset D⊂Rn is supported on the attractor (or invariant set) of the iterated function system {?d(x)=M⁻¹(x+d)}_d∈D. The spectral and non-spectral problems on μM,D, including the spectrum-tiling problem implied in them, have received much attention in recent years. One of the non-spectral problem on μM,D is to estimate the number of orthogonal exponentials in L²(μM,D) and to find them. In the present paper we show that if a,b,c∈Z, |a|>1, |c|>1 and ac∈Z?(3Z),

     

An aperiodic set of 13 Wang tiles

A new aperiodic tile set containing only 13 tiles over 5 colors is presented. Its construction is based on a recent technique developed by Kari. The tilings simulate the behavior of sequential machines that multiply real numbers in balanced representations by real constants.     

A small aperiodic set of Wang tiles

A new aperiodic tile set containing only 14 Wang tiles is presented. The construction is based on Mealy machines that multiply Beatty sequences of real numbers by rational constants.     

Distinct distances between a collinear set and an arbitrary set of points

We consider the number of distinct distances between two finite sets of points in ${\mathbb{R}}^k$, for any constant dimension $k\ge 2$, where one set $P_1$ consists of $n$ points on a line $l$, and the other set $P_2$ consists of $m$ arbitrary points, such that no hyperplane orthogonal to $l$ and no hypercylinder having $l$ as its axis contains more than $O\left(1\right)$ points of $P_2$. The number of distinct distances between $P_1$ and $P_2$ is then

$\Omega \left(min\left\{n^{2∕3}{m}^{2∕3},\frac{n^{10∕11}{m}^{4∕11}}{{log}^{2∕11}m},n^2,m^2\right\}\right).$

Without the assumption on $P_2$, there exist sets $P_1$, $P_2$ as above, with only $O(m+n)$ distinct distances between them.     

一类四元素数字集的正交函数的个数

自仿测度的谱与非谱问题近年引起了很大的关注,关于自仿测度的非谱问题,其中之一就是要估算它在L2空间上的正交指数的个数．通过对μM,D傅里叶变换的零点集性质的分析和讨论,对现有的结论进行了改进,确定了相应四元素数字集的平面自仿测度在L2的空间上正交指数函数的最大个数为3．     

A strongly aperiodic set of tiles in the hyperbolic plane

We construct the first known example of a strongly aperiodic set of tiles in the hyperbolic plane. Such a set of tiles does admit a tiling, but admits no tiling with an infinite cyclic symmetry. This can also be regarded as a regular production system [5] that does admit bi-infinite orbits, but admits no periodic orbits.     

Coloring copoints of a planar point set

To a set of n points in the plane, one can associate a graph that has less than n² vertices and has the property that k-cliques in the graph correspond vertex sets of convex k-gons in the point set. We prove an upper bound of 2^k-1 on the size of a planar point set for which the graph has chromatic number k, matching the bound conjectured by Szekeres for the clique number. Constructions of Erd?s and Szekeres are shown to yield graphs that have very low chromatic number. The constructions are carried out in the context of pseudoline arrangements.     

On convex decompositions of a planar point set

Let P be a planar point set in general position. Neumann-Lara et al. showed that there is a convex decomposition of P with at most elements. In this paper, we improve this upper bound to .