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10 votes
2 answers
1k views

Decidability of periodic tilings of the plane

I'm interested in tilings of the plane by squares, with labels on the edges. It's well known that (1) the question "can one tile the plane with the following finite set of tiles?" is undecidable, and (...
grok's user avatar
  • 2,519
5 votes
1 answer
289 views

The spectral radius of a binary matrix - polynomial growth?

(This is a follow-up to The spectral radius of a binary matrix) Let $\mathcal B_n$ denote the set of $n\times n$ matrices with entries in $\{0,1\}$. QUESTION. Is there a $\delta\in\bigl(0,\frac12\...
Nikita Sidorov's user avatar
9 votes
1 answer
210 views

Can the full shift be embedded in a flow?

Write $I=[0,1]$, and let $S$ be the shift on $X=\{ (x_n)_{n\in\mathbb Z} : x_n\in I^k \}$. Is there a flow $\phi_t$ on $X$ with $\phi_1=S$? Here I require that $\phi_t$, for fixed $t$, is at least a ...
Christian Remling's user avatar
8 votes
1 answer
436 views

The graph of Rule 110 and vertices degree

Consider the elementary cellular automaton called Rule 110 (famous for being Turing complete): It induces a map $R: \mathbb{N} \to \mathbb{N}$ such that the binary representation of $R(n)$ is ...
Sebastien Palcoux's user avatar
8 votes
1 answer
631 views

Aproximating dynamical systems by intrinsically ergodic systems

Let $X$ be a compact metric space and $f:X \to X$ a continuous map. We say that $(X,f)$ is approximated from below by a sequence of compact metric spaces $(X_i)_{i \geq 1}$ and a sequence of ...
Rafael Alcaraz Barrera's user avatar
4 votes
2 answers
273 views

Lower bounds for pattern complexity of aperiodic subshifts

In the setting of symbolic dynamics over $\mathbb{Z}^d$, one can define for the $n$-th pattern complexity of a given a subshift $\Omega\subseteq \mathcal{A}^{\mathbb{Z}^d}$ as $$ c_n(\Omega):= \Big\...
Keen-ameteur's user avatar
3 votes
2 answers
416 views

Fast algorithms for external angle computations

Two related problems related to the complex quadratic polynomial $f_c(z) = z^2 + c$ and Mandelbrot and/or Julia sets: find an external angle $\theta_c$ for a complex point $c$ find a complex point $...
Claude's user avatar
  • 111
3 votes
1 answer
120 views

Almost one-to-one endomorphism of minimal subshift?

Let $(X,T)$ be a minimal subshift. Can it happen that an endomorphism $\varphi\colon (X,T) \to (X,T)$ is almost 1-to-1 but not 1-to-1? Can it happen that a factor $\pi\colon (X,T) \to (Y,T)$ between ...
Veridian Dynamics's user avatar
2 votes
3 answers
638 views

The critical exponent function

It is a known fact [1] that, for every $c\in (1,\infty]$, it is possible to find a finite alphabet $\mathcal{A}$ and a word $w\in \mathcal{A}^\omega$ such that $w$ has critical exponent $c$. It looks ...
Alessandro Della Corte's user avatar