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In this paper we consider the Erd\H{o}s-R\'enyi random graph in the sparse regime in the limit as the number of vertices $n$ tends to infinity. We are interested in what this graph looks like when it contains many triangles, in two…

概率论 · 数学 2026-01-27 Suman Chakraborty , Remco van der Hofstad , Frank den Hollander

Given an ordered sequence of $N$-choose-2 integers, we give necessary and sufficient conditions to have an ordered collection of $N$ simple closed curves on a torus such that the algebraic pairwise intersections of those curves are the…

几何拓扑 · 数学 2025-08-25 Ferit Öztürk

We prove that it is $\#\mathsf{P}$-complete to count the triangulations of a (non-simple) polygon.

计算几何 · 计算机科学 2020-12-07 David Eppstein

We discuss an unusual phenomenon in (integral) positive ternary quadratic forms. We also describe an interesting pairing of genera of ternary forms.

数论 · 数学 2012-05-11 William C. Jagy

A rational spherical triangle is a triangle on the unit sphere such that the lengths of its three sides and its area are rational multiples of $\pi$. Little and Coxeter have given examples of rational spherical triangles in 1980s. In this…

数论 · 数学 2023-12-05 Haiyang Wang

We study those rings in which all invertible elements are weakly nil-clean calling them {\it UWNC rings}. This somewhat extends results due to Karimi-Mansoub et al. in Contemp. Math. (2018), where rings in which all invertible elements are…

环与代数 · 数学 2024-02-06 Peter Danchev , Omid Hasanzadeh , Arash Javan , Ahmad Moussavi

In this paper, we prove that if a finite number of rectangles, every of which has at least one integer side, perfectly tile a big rectangle then there exists a strategy which reduces the number of these tiles (rectangles) without violating…

历史与综述 · 数学 2011-11-30 Sultan Hussain , Usman Ali

Let $k\ge 2$ and $n_1\ge n_2\ge n_3\ge n_4$ be integers such that $n_4$ is sufficiently larger than $k$. We determine the maximum number of edges of a 4-partite graph with parts of sizes $n_1,\dots, n_4$ that does not contain $k$…

组合数学 · 数学 2021-11-23 Jie Han , Yi Zhao

The relevance of this paper lies in the fact that it resolves two previously unsolved open problems. In the first part of the paper, a new lemma is proved, from which it follows that if there exists a triangle with integer sides and…

组合数学 · 数学 2026-03-24 Logman Shihaliev

A ring R is said to be VNL if for any a in R, either a or 1-a is (von Neumann) regular. The class of VNL rings lies properly between the exchange rings and (von Neumann) regular rings. We characterize abelian VNL rings. We also characterize…

环与代数 · 数学 2008-01-17 Harpreet K. Grover , Dinesh Khurana

We improve the estimates of the subgraph probabilities in a random regular graph. Using the improved results, we further improve the limiting distribution of the number of triangles in random regular graphs.

组合数学 · 数学 2023-02-03 Pu Gao

An N -tiling of triangle ABC by triangle T is a way of writing ABC as a union of N triangles congruent to T, overlapping only at their boundaries. The triangle T is the "tile'". The tile may or may not be similar to ABC . This paper is the…

度量几何 · 数学 2012-06-12 Michael Beeson

Fix an integer n>=1. Suppose that a simple polygon is the union of n triangles whose vertices along the common boundary are arranged cyclically. How many sides can such a union -- to be called regular -- have at most? This gives OEIS…

组合数学 · 数学 2026-04-16 Giedrius Alkauskas

We provide an algorithm for computing the number of integral points lying in certain triangles that do not have integral vertices. We use techniques from Algebraic Geometry such as the Riemann-Roch formula for weighted projective planes and…

代数几何 · 数学 2024-02-29 Jorge Martín-Morales

In this work initial numbers and repunit numbers have been studied. All numbers have been considered in a decimal notation. The problem of simplicity of initial numbers has been studied. Interesting properties of numbers repunit are proved:…

综合数学 · 数学 2007-05-23 Boris V. Tarasov

The degenerate Stirling numbers of the second kind and of the first kind, which are respectively degenerate versions of the Stirling numbers of the second kind and of the first kind, appear frequently when we study various degenerate…

数论 · 数学 2022-06-10 Taekyun Kim , Dae san Kim , Hye Kyung Kim

We obtain new upper and lower bounds on the number of unit perimeter triangles spanned by points in the plane. We also establish improved bounds in the special case where the point set is a section of the integer grid.

组合数学 · 数学 2025-10-06 Ritesh Goenka , Kenneth Moore , Ethan Patrick White

Given real numbers whose sum is an integer, we study the problem of finding integers which match these real numbers as closely as possible, in the sense of L^p norm, while preserving the sum. We describe the structure of solutions for this…

数据结构与算法 · 计算机科学 2015-01-05 Rama Cont , Massoud Heidari

We introduce a computational origami problem which we call the segment folding problem: given a set of $n$ line-segments in the plane the aim is to make creases along all segments in the minimum number of folding steps. Note that a folding…

计算几何 · 计算机科学 2022-01-17 Takashi Horiyama , Fabian Klute , Matias Korman , Irene Parada , Ryuhei Uehara , Katsuhisa Yamanaka

We show that every minimum area isosceles triangle containing a given triangle $T$ shares a side and an angle with $T$. This proves a conjecture of Nandakumar motivated by a computational problem. We use our result to deduce that for every…

度量几何 · 数学 2020-09-04 Gergely Kiss , János Pach , Gábor Somlai