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1 answer
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Chromatic tiling complexity and the chromatic number conjecture

Let $T$ be a finite set of tiles in $\mathbb{R}^d$. A tiling of $\mathbb{R}^d$ by $T$ is a collection of disjoint translates of tiles in $T$ whose union is $\mathbb{R}^d$. A tiling is $k$-chromatic if ...
Vincenco Fedor's user avatar
3 votes
2 answers
279 views

Construct by compactness (Pentagonal tiling – Rao paper)

In the (arXiv) paper, Exhaustive search of convex pentagons which tile the plane by Michael Rao, on page 4 under the proof of Lemma 2, it is said that: "… We keep a connected component $H_d'$ of $...
GingerBreadMan's user avatar
0 votes
0 answers
140 views

Graph theory: Closed neighourhoods and generalized clustering coefficients

The neighbourhood of node $v$ in graph $G$ is the subgraph of $G$ induced by all vertices adjacent to $v$. The number of edges between neighbours divided by the number of pairs of neighbours is ...
Hans-Peter Stricker's user avatar
3 votes
0 answers
83 views

Distance spectra of uniform tilings

Let a uniform tiling be defined by a vertex configuration $(n_1.n_2.\cdots.n_k)^m$, which is either spherical, Euclidean or hyperbolic. Assume that the tiling is vertex-transitive, especially that ...
Hans-Peter Stricker's user avatar
4 votes
1 answer
284 views

Structures for random graphs with structure

Background[You may skip this and go immediately to the Definitions.] Crucial features of a (random) graph or network are: the degree distribution $p(d)$ (exponential, Poisson, or power law) the mean ...
Hans-Peter Stricker's user avatar
5 votes
3 answers
434 views

Can local flip moves connect dimer matchings on 'quadrangulated' planar bipartite graphs? (perfect matching reconfiguration problem)

I'm interested in the structure of dimer matchings on planar graphs with a bipartite structure. In particular, I'm interested in whether any two perfect matchings can be connected, i.e. transformed ...
Joe's user avatar
  • 545
5 votes
3 answers
748 views

Aperiodic graphs

The concepts of being non-periodic and aperiodic for tilings have obvious versions for connected graphs with a countable set of vertices and a finite number of edges meeting at each vertex. A graph $G$...
Jesús Álvarez's user avatar
6 votes
0 answers
657 views

Unique domino tiling

Question: how does one enumerate all star-convex $2n$-vertex sublattices of the plane that have the unique domino-tiling property? Definitions: A subset $S$ of the $xy$-plane is star-convex if there ...
John Murray's user avatar
  • 1,090
21 votes
1 answer
1k views

Monomer-Dimer tatami tilings need better relationships with other math. Summary of results

A monomer-dimer tiling of a rectangular grid with $r$ rows and $c$ columns satisfies the tatami condition if no four tiles meet at any point. (Or you can think of it as the removal of a matching from ...
Alejandro Erickson's user avatar
4 votes
1 answer
315 views

Representing groups with two generators as graph automorphisms

Suppose we have a group $G$ which can be generated by two elements $x$, $y$. Call $H$, $K$, $L$ the subgroups of $G$ generated by $x$, $y$ and $y^{-1}x^{-1}$, respectively. With these data, we can ...
Giovanni Moreno's user avatar