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We give a short proof of Belaga's result on bounds to perigees of $(3x+d)$-cycles of a given oddlength. We also reformulate the Collatz cycle conjecture which is rather a algorithmic problem into a purely arithmetic problem.

Number Theory · Mathematics 2014-09-23 Masayoshi Kaneda

The famous Gallai's Conjecture states that any connected graph with n vertices has a path decomposition containing at most (n+1)/2 paths. In this note, we explore graphs generated from removing edges from complete graphs. We first provide…

Combinatorics · Mathematics 2022-11-01 Hua Wang , Andrew Zhang

Gallai's colouring theorem states that if the edges of a complete graph are 3-coloured, with each colour class forming a connected (spanning) subgraph, then there is a triangle that has all 3 colours. What happens for more colours: if we…

Combinatorics · Mathematics 2014-02-24 Imre Leader , Ta Sheng Tan

We offer a new structural basis for the theory of 3-connected graphs, providing a unique decomposition of every such graph into parts that are either quasi 4-connected, wheels, or thickened $K_{3,m}$'s. Our construction is explicit,…

Combinatorics · Mathematics 2025-07-25 Johannes Carmesin , Jan Kurkofka

In this paper, we prove a tight minimum degree condition in general graphs for the existence of paths between two given endpoints, whose lengths form a long arithmetic progression with common difference one or two. This allows us to obtain…

Combinatorics · Mathematics 2021-01-27 Jun Gao , Qingyi Huo , Chun-Hung Liu , Jie Ma

A Gallai coloring is a coloring of the edges of a complete graph without rainbow triangles, and a Gallai $k$-coloring is a Gallai coloring that uses at most $k$ colors. For an integer $k\geq 1$, the Gallai-Ramsey number $GR_k(H)$ of a given…

Combinatorics · Mathematics 2020-09-17 Fangfang Zhang , Zi-Xia Song , Yaojun Chen

The $3x+1$ problem, also called the Collatz conjecture, is a very interesting unsolved mathematical problem related to computer science. This paper generalized this problem by relaxing the constraints, i.e., generalizing this deterministic…

Computational Complexity · Computer Science 2013-11-25 Bojin Zheng , Yangqian Su , Hongrun Wu , Li Kuang

In this article we present set of infinite natural numbers which satisfies the conjecture $3n+1$.

General Mathematics · Mathematics 2016-08-05 G. H. S. Costa , A. C. Souza Filho

In the way of proving Kneser's conjecture, L\'{a}szl\'{o} Lov\'{a}sz settled out a new lower bound for the chromatic number of graphs. He showed that if the hom complex $||Hom(\mathcal{K}_2, H)||$ of a graph $H$ is topologically…

Combinatorics · Mathematics 2017-09-21 Hamid Reza Daneshpajouh

We introduce an infinite set of integer mappings that generalize the well-known Collatz-Ulam mapping and we conjecture that an infinite subset of these mappings feature the remarkable property of the Collatz conjecture, namely that they…

Number Theory · Mathematics 2008-10-30 M. Bruschi

We give a necessary and sufficient condition for a cubic graph to be Hamiltonian by analyzing Eulerian tours in certain spanning subgraphs of the quartic graph associated with the cubic graph by 1-factor contraction. This correspondence is…

Combinatorics · Mathematics 2015-08-11 Simona Bonvicini , Tomaž Pisanski

For a number $l\geq 2$, let ${\cal{G}}_l$ denote the family of graphs which have girth $2l+1$ and have no odd hole with length greater than $2l+1$. Wu, Xu and Xu conjectured that every graph in $\bigcup_{l\geq 2} {\cal{G}}_{l}$ is…

Combinatorics · Mathematics 2023-07-06 Yan Wang , Rong Wu

For the OEIS sequence A176677, defined by the quadratic convolution recurrence $a(0) = a(1) = 1$ and $a(n+1) = \sum_{p=0}^n a(p) a(n-p) - 1$ for $n \ge 1$, R.~J.~Mathar contributed in March 2016 the conjectured order-4 P-recursive…

Combinatorics · Mathematics 2026-05-07 Tong Niu

Lov\'asz conjectured that every connected 4-regular planar graph G admits a realization as a system of circles, i.e., it can be drawn on the plane utilizing a set of circles, such that the vertices of G correspond to the intersection and…

Data Structures and Algorithms · Computer Science 2019-09-05 Michael A. Bekos , Chrysanthi N. Raftopoulou

The Collatz problem with $3x+k$ is revisited. Positive and negative limit cycles are given up to k=9997 starting with $x_0=-2\cdot10^7...+2\cdot10^7$. A simple relation between the probability distribution for the Syracuse iterates for…

Dynamical Systems · Mathematics 2021-01-21 Franz Wegner

A Gallai coloring is a coloring of the edges of a complete graph without rainbow triangles, and a Gallai $k$-coloring is a Gallai coloring that uses at most $k$ colors. Given an integer $k\ge1$ and graphs $H_1, \ldots, H_k$, the…

Combinatorics · Mathematics 2019-09-25 Zi-Xia Song , Jingmei Zhang

A path decomposition of a graph $G$ is a collection of edge-disjoint paths of $G$ that covers the edge set of $G$. Gallai (1968) conjectured that every connected graph on $n$ vertices admits a path decomposition of cardinality at most…

Combinatorics · Mathematics 2018-03-20 Fábio Botler , Andrea Jiménez , Maycon Sambinelli

The one way function based on the Collatz problem is proposed. It is based on the problem's conditional branching structure which is not considered as important even the 3x+1 question is quite famous. The analysis shows why the problem is…

Computational Complexity · Computer Science 2018-07-27 Rade Vuckovac

A colored graph is a complete graph in which a color has been assigned to each edge, and a colorful cycle is a cycle in which each edge has a different color. We first show that a colored graph lacks colorful cycles iff it is Gallai, i.e.,…

Combinatorics · Mathematics 2015-09-21 Richard N. Ball , Aleš Pultr , Petr Vojtěchovský

Let $R$ be a ring. The unitary addition Cayley graph of $R$, denoted $\mathcal{U}(R)$, is the graph with vertex $R$, and two distinct vertices $x$ and $y$ are adjacent if and only if $x+y$ is a unit. We determine a formula for the clique…

Combinatorics · Mathematics 2025-04-29 Keenan Calhoun , Yeşim Demiroğlu Karabulut , Vincent Pigno , Craig Timmons