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We find the exact values of complexity for an infinite series of 3-manifolds. Namely, by calculating hyperbolic volumes, we show that c(N_n)=2n, where $c$ is the complexity of a 3-manifold and N_n is the total space of the punctured torus…

Geometric Topology · Mathematics 2007-05-23 Sergei Anisov

We report the detection for the first time in space of three new pure hydrocarbon cycles in TMC-1: c-C3HCCH (ethynyl cyclopropenylidene), c-C5H6 (cyclopentadiene) and c-C9H8 (indene). We derive a column density of 3.1e11 cm-2 for the former…

Astrophysics of Galaxies · Physics 2021-05-19 J. Cernicharo , M. Agundez , C. Cabezas , B. Tercero , N. Marcelino , J. R. Pardo , P. de Vicente

The Prime Number Theorem asserts that the density of primes less than or equal to $N$ is asymptotically equal to $1/\log N$. The density of prime triples in coprime triples in $\mathbb{Z}^3_+$ is determined to be $3\zeta (3)/\log N$, where…

Number Theory · Mathematics 2025-12-29 Liang Geng , Wei He , Rongwei Yang

How small can a set of vertices in the $n$-dimensional hypercube $Q_n$ be if it meets every copy of $Q_d$? The asymptotic density of such a set (for $d$ fixed and $n$ large) is denoted by $\gamma_d$. It is easy to see that $\gamma_d \leq…

Combinatorics · Mathematics 2025-07-11 David Ellis , Maria-Romina Ivan , Imre Leader

We report on the design and demonstration of ${\beta}-(Al_{0.18}Ga_{0.82})_2O_3/Ga_2O_3$ modulation doped heterostructures to achieve high sheet charge density. The use of a thin spacer layer between the Si delta-doping and heterojunction…

A $k$-graph (or $k$-uniform hypergraph) $H$ is uniformly dense if the edge distribution of $H$ is uniformly dense with respect to every large collection of $k$-vertex cliques induced by sets of $(k-2)$-tuples. Reiher, R\"odl and Schacht…

Combinatorics · Mathematics 2023-05-03 Hao Lin , Guanghui Wang , Wenling Zhou

In this paper we determine new upper bounds for the maximal density of translative packings of superballs in three dimensions (unit balls for the $l^p_3$-norm) and of Platonic and Archimedean solids having tetrahedral symmetry. Thereby, we…

Metric Geometry · Mathematics 2017-07-31 Maria Dostert , Cristóbal Guzmán , Fernando Mário de Oliveira Filho , Frank Vallentin

Extremal problems for $3$-uniform hypergraphs are known to be very difficult and despite considerable effort the progress has been slow. We suggest a more systematic study of extremal problems in the context of quasirandom hypergraphs. We…

Combinatorics · Mathematics 2018-05-29 Christian Reiher , Vojtěch Rödl , Mathias Schacht

Reiher, R\"odl, Sales, and Schacht initiated the study of relative Tur\'an densities of ordered graphs and showed that it is more subtle and interesting than the unordered case. For an ordered graph $F$, its relative Tur\'an density,…

Combinatorics · Mathematics 2025-11-27 Freddie Illingworth , Arjun Ranganathan , Leo Versteegen , Ella Williams

We generalise a result of Corr\'{a}di and Hajnal and show that every graph with average degree at least $\tfrac{4}{3}kr$ contains $k$ vertex disjoint cycles, each of order at least $r$, as long as $k \geq 6$. This bound is sharp when $r=3$.

Combinatorics · Mathematics 2015-02-13 Daniel J. Harvey , David R. Wood

We show that for any fixed $\alpha>0$, cherry-quasirandom 3-graphs of positive density and sufficiently large order $n$ with minimum vertex degree $\alpha \binom n2$ have a tight Hamilton cycle. This solves a conjecture of Aigner-Horev and…

Combinatorics · Mathematics 2020-04-28 Luyining Gan , Jie Han

We performed high resolution numerical simulations of homogenous and isotropic compressible turbulence, with an average 3D Mach number close to 0.3. We study the statistical properties of intermittency for velocity, density and entropy. For…

Chaotic Dynamics · Physics 2009-11-13 Roberto Benzi , Luca Biferale , Robert Fisher , Leo Kadanoff , Donald Lamb , Federico Toschi

Given a family of $r$-uniform hypergraphs ${\cal F}$ (or $r$-graphs for brevity), the Tur\'an number $ex(n,{\cal F})$ of ${\cal F}$ is the maximum number of edges in an $r$-graph on $n$ vertices that does not contain any member of ${\cal…

Combinatorics · Mathematics 2015-10-14 Axel Brandt , David Irwin , Tao Jiang

In a recent paper, Chao and Yu used an entropy method to show that the Tur\'an density of a certain family $\mathcal{F}$ of $\lfloor r/2\rfloor$ triangle-like $r$-uniform hypergraphs is $r!/r^r$. Later, Liu determined for large $n$ the…

Combinatorics · Mathematics 2025-03-25 Daniel Iľkovič , Jun Yan

In this paper, we prove several new Tur\'an density results for 3-graphs with independent neighbourhoods. We show: \pi(K_4^-, C_5, F_{3,2})=12/49, \pi(K_4^-, F_{3,2})=5/18, and \pi(J_4, F_{3,2})=\pi(J_5, F_{3,2})=3/8, where J_t is the…

Combinatorics · Mathematics 2015-03-13 Victor Falgas-Ravry , Emil R. Vaughan

We introduce a unified ensemble for turbo-like codes (TCs) that contains the four main classes of TCs: parallel concatenated codes, serially concatenated codes, hybrid concatenated codes, and braided convolutional codes. We show that for…

Information Theory · Computer Science 2017-03-28 Saeedeh Moloudi , Michael Lentmaier , Alexandre Graell i Amat

We investigate natural Tur\'an problems for mixed graphs, generalizations of graphs where edges can be either directed or undirected. We study a natural \textit{Tur\'an density coefficient} that measures how large a fraction of directed…

Combinatorics · Mathematics 2024-03-26 Nitya Mani , Edward Yu

The transport coefficients of strongly interacting matter are currently subject of intense theoretical and phenomenological studies due to their relevance for the characterization of the quark-gluon plasma produced in ultra relativistic…

High Energy Physics - Phenomenology · Physics 2015-05-05 A. Puglisi , S. Plumari , V. Greco

The planar Tur\'an number ${\rm ex}_{\mathcal{P}}(n,C_k)$ is the largest number of edges in an $n$-vertex planar graph with no cycle of length $k$. Let $k\ge 11$ and $C,D$ be constants. Cranston, Lidick\'y, Liu and Shantanam…

Combinatorics · Mathematics 2023-10-12 Ervin Győri , Kitti Varga , Xiutao Zhu

It has been known for almost 200 years that some angles cannot be trisected by straightedge and compass alone. This paper studies the set of such angles as well as its complement $\mathcal{T}$, both regarded as subsets of the unit circle…

Number Theory · Mathematics 2011-08-16 Peter J. Kahn