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This paper contains a survey of supersingular isogeny graphs associated to supersingular elliptic curves and their various applications to cryptography. Within limitation of space, we attempt to address a broad audience and make this part…

Number Theory · Mathematics 2025-06-04 Eyal Z. Goren , Jonathan R. Love

In the degree-diameter problem for Abelian Cayley and circulant graphs of diameter 2 and arbitrary degree d there is a wide gap between the best lower and upper bounds valid for all d, being quadratic functions with leading coefficient 1/4…

Combinatorics · Mathematics 2015-06-10 Robert R. Lewis

We prove that uniform Roe C*-algebras associated to some expander graphs coming from discrete groups with property (\tau) are not K-exact. In particular, we show that this is the case for the expander obtained as Cayley graphs of a sequence…

Operator Algebras · Mathematics 2009-07-15 Jan Spakula

In this paper we show lower bounds for a certain large class of algorithms solving the Graph Isomorphism problem, even on expander graph instances. Spielman [25] shows an algorithm for isomorphism of strongly regular expander graphs that…

Computational Complexity · Computer Science 2016-10-31 Aaron Snook , Grant Schoenebeck , Paolo Codenotti

In this paper, we aim to address the open questions raised in various recent papers regarding characterization of circulant graphs with three or four distinct eigenvalues in their spectra. Our focus is on providing characterizations and…

Combinatorics · Mathematics 2023-10-11 Milan Bašić

The main contribution of this work is a new type of graph product, which we call the {\it zig-zag product}. Taking a product of a large graph with a small graph, the resulting graph inherits (roughly) its size from the large one, its degree…

Combinatorics · Mathematics 2007-05-23 Omer Reingold , Salil Vadhan , Avi Wigderson

We express the discrete Ricci curvature of a graph as the minimal eigenvalue of a family of matrices, one for each vertex of a graph whose entries depend on the local adjaciency structure of the graph. Using this method we compute or bound…

Combinatorics · Mathematics 2022-04-20 Viola Siconolfi

Expander graphs, due to their mixing properties, are useful in many algorithms and combinatorial constructions. One can produce an expander graph with high probability by taking a random graph (e.g., the union of $d$ random bijections for a…

Combinatorics · Mathematics 2024-05-30 Geoffroy Caillat-Grenier

We classify the distance-regular Cayley graphs with least eigenvalue $-2$ and diameter at most three. Besides sporadic examples, these comprise of the lattice graphs, certain triangular graphs, and line graphs of incidence graphs of certain…

Combinatorics · Mathematics 2016-04-28 Alireza Abdollahi , Edwin van Dam , Mojtaba Jazaeri

We show that every regular graph with good local expansion has a spanning Lipschitz subgraph with large girth and minimum degree. In particular, this gives a finite analogue of the dynamical solution to the von Neumann problem by Gaboriau…

Group Theory · Mathematics 2021-12-06 Gabor Kun

We provide an explicit construction of finite 4-regular graphs $(\Gamma_k)_{k\in \mathbb N}$ with ${girth \Gamma_k\to\infty}$ as $k\to\infty$ and $\frac{diam \Gamma_k}{girth \Gamma_k}\leqslant D$ for some $D>0$ and all $k\in\mathbb{N}$. For…

Group Theory · Mathematics 2022-08-25 Goulnara Arzhantseva , Arindam Biswas

The unipotent subgroup of a finite group of Lie type over a prime field Z/pZ comes equipped with a natural set of generators; the properties of the Cayley graph associated to this set of generators have been much studied. In the present…

Group Theory · Mathematics 2007-05-23 Jordan S. Ellenberg , Julianna S. Tymoczko

We construct explicit generating sets S_n and \tilde S_n of the for the alternating and the symmetric groups, which turn the Cayley graphs C(Alt(n), S_n) and C(Sym(n), \tilde S_n) into a family of bounded degree expanders for all n. This…

Group Theory · Mathematics 2007-05-23 Martin Kassabov

We investigate Cayley graphs of graph products by showing that graph products with vertex groups that have isomorphic Cayley graphs yield isomorphic Cayley graphs.

Group Theory · Mathematics 2025-03-20 Marjory Mwanza

We prove that if L is a finite simple group of Lie type and A a symmetric set of generators of L, then A grows i.e |AAA| > |A|^{1+epsilon} where epsilon depends only on the Lie rank of L, or AAA=L. This implies that for a family of simple…

Group Theory · Mathematics 2011-04-11 László Pyber , Endre Szabó

In this paper we are interested in the asymptotic enumeration of Cayley graphs. It has previously been shown that almost every Cayley digraph has the smallest possible automorphism group: that is, it is a digraphical regular representation…

Combinatorics · Mathematics 2020-05-18 Joy Morris , Mariapia Moscatiello , Pablo Spiga

This paper represents a significant leap forward in the problem of enumerating vertex-transitive graphs. Recent breakthroughs on symmetry of Cayley (di)graphs show that almost all finite Cayley (di)graphs have the smallest possible…

Combinatorics · Mathematics 2025-11-25 Yunsong Gan , Pablo Spiga , Binzhou Xia

We consider the family of undirected Cayley graphs associated with odd cyclic groups, and study statistics for the eigenvalues in their spectra. Our results are motivated by analogies between arithmetic geometry and graph theory.

Combinatorics · Mathematics 2024-09-04 Matilde Lalin , Anwesh Ray

We consider quasirandom properties for Cayley graphs of finite abelian groups. We show that having uniform edge-distribution (i.e., small discrepancy) and having large eigenvalue gap are equivalent properties for such Cayley graphs, even if…

Combinatorics · Mathematics 2016-10-21 Yoshiharu Kohayakawa , Vojtěch Rödl , Mathias Schacht

Does every $n$-vertex Cayley graph have an orthonormal eigenbasis all of whose coordinates are $O(1/\sqrt{n})$? While the answer is yes for abelian groups, we show that it is no in general. On the other hand, we show that every $n$-vertex…

Combinatorics · Mathematics 2020-10-29 Ashwin Sah , Mehtaab Sawhney , Yufei Zhao