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We construct new resolvable decompositions of complete multigraphs and complete equipartite multigraphs into cycles of variable lengths (and a perfect matching if the vertex degrees are odd). We develop two techniques: {\em layering}, which…

Combinatorics · Mathematics 2018-09-26 Amin Bahmanian , Mateja Šajna

We establish necessary and sufficient conditions for the existence of a decomposition of a complete multigraph into edge-disjoint cycles of specified lengths, or into edge-disjoint cycles of specified lengths and a perfect matching.

Combinatorics · Mathematics 2015-08-05 Darryn Bryant , Daniel Horsley , Barbara Maenhaut , Benjamin R. Smith

We show that the complete graph on $n$ vertices can be decomposed into $t$ cycles of specified lengths $m_1,\ldots,m_t$ if and only if $n$ is odd, $3\leq m_i\leq n$ for $i=1,\ldots,t$, and $m_1+\cdots+m_t=\binom n2$. We also show that the…

Combinatorics · Mathematics 2018-05-16 Darryn Bryant , Daniel Horsley , William Pettersson

In 1981, Alspach conjectured that the complete graph $ K_{n} $ could be decomposed into cycles of arbitrary lengths, provided that the obvious necessary conditions would hold. This conjecture was proved completely by Bryant, Horsley and…

Combinatorics · Mathematics 2016-09-07 Ramin Javadi , Afsaneh Khodadadpour , Gholamreza Omidi

The Hamilton-Waterloo problem asks for which $s$ and $r$ the complete graph $K_n$ can be decomposed into $s$ copies of a given 2-factor $F_1$ and $r$ copies of a given 2-factor $F_2$ (and one copy of a 1-factor if $n$ is even). In this…

Combinatorics · Mathematics 2016-05-09 Melissa Keranen , Adrián Pastine

We examine the necessary and sufficient conditions for a complete symmetric equipartite digraph $K_{n[m]}^\ast$ with $n$ parts of size $m$ to admit a resolvable decomposition into directed cycles of length $t$. We show that the obvious…

Combinatorics · Mathematics 2023-03-09 Nevena Francetić , Mateja Šajna

In a graph $G$, let $\mu_G(xy)$ denote the number of edges between $x$ and $y$ in $G$. Let $\lambda K_{v,u}$ be the graph $(V\cup U,E)$ with $|V|=v$, $|U|=u$, and \[ \mu_G(xy)=\begin{cases} \lambda &\mbox{if $x\in U$ and $y\in V$ or if…

Combinatorics · Mathematics 2016-09-27 John Asplund , Joe Chaffee , James Hammer

We prove that the complete graph with a hole $K_{u+w}-K_u$ can be decomposed into cycles of arbitrary specified lengths provided that the obvious necessary conditions are satisfied, each cycle has length at most $\min(u,w)$, and the longest…

Combinatorics · Mathematics 2016-03-15 Daniel Horsley , Rosalind A. Hoyte

Bryant, Horsley, Maenhaut and Smith recently gave necessary and sufficient conditions for when the complete multigraph can be decomposed into cycles of specified lengths $m_1,m_2,\ldots,m_\tau$. In this paper we characterise exactly when…

Combinatorics · Mathematics 2017-12-22 Rosalind A. Cameron

We prove that $K_n+I$, the complete graph of an even order with a $1$-factor duplicated, admits a decomposition into $2$-factors, each a disjoint union of cycles of length $m \geq 5$ if and only if $m \mid n$, except possibly when $m$ is…

Combinatorics · Mathematics 2024-08-01 Noah Bolohan , Iona Buchanan , Andrea Burgess , Mateja Šajna , Ryan Van Snick

We prove that a complete bipartite graph can be decomposed into cycles of arbitrary specified lengths provided that the obvious necessary conditions are satisfied, the length of each cycle is at most the size of the smallest part, and the…

Combinatorics · Mathematics 2012-04-17 Daniel Horsley

We show that the complete symmetric digraph $K_{2m}^\ast$ admits a resolvable decomposition into directed cycles of length $m$ for all odd $m$, $5 \le m \le 49$. Consequently, $K_{n}^\ast$ admits a resolvable decomposition into directed…

Combinatorics · Mathematics 2017-06-22 Andrea Burgess , Nevena Francetic , Mateja Sajna

We prove that a complete multipartite graph $K$ with $n>1$ vertices and $m$ edges can be decomposed into edge-disjoint Hamilton paths if and only if $\frac m{n-1}$ is an integer and the maximum degree of $K$ is at most $\frac {2m}{n-1}$.

Combinatorics · Mathematics 2018-07-24 Darryn Bryant , Hao Chuien Hang , Sarada Herke

In this paper, we study the existence problem for cyclic $\ell$-cycle decompositions of the graph $K_m[n]$, the complete multipartite graph with $m$ parts of size $n$, and give necessary and sufficient conditions for their existence in the…

Combinatorics · Mathematics 2019-10-29 Andrea Burgess , Francesca Merola , Tommaso Traetta

We say a graph $H$ decomposes a graph $G$ if there exists a partition of the edges of $G$ into subgraphs isomorphic to $H$. We seek to characterize necessary and sufficient conditions for a cycle of length $k$, denoted $C_k$, to decompose…

Combinatorics · Mathematics 2023-10-23 Moriah Aberle , Sarah Gold , Rivkah Moshe , David Offner

We show that $k$-uniform hypergraphs on $n$ vertices whose codegree is at least $(2/3 + o(1))n$ can be decomposed into tight cycles, subject to the trivial divisibility conditions. As a corollary, we show those graphs contain tight Euler…

Combinatorics · Mathematics 2024-03-07 Allan Lo , Simón Piga , Nicolás Sanhueza-Matamala

Let $k$, $\lambda$ and $\mu$ be positive integers. A decomposition of a multigraph $ \lambda G$ into edge-disjoint subgraphs $G_1, \ldots , G_k$ is said to be \emph{enclosed} by a decomposition of a multigraph $\mu H$ into edge-disjoint…

Combinatorics · Mathematics 2016-08-26 Carl Feghali , Matthew Johnson

A detachment of a hypergraph $\scr F$ is a hypergraph obtained from $\scr F$ by splitting some or all of its vertices into more than one vertex. Amalgamating a hypergraph $\scr G$ can be thought of as taking $\scr G$, partitioning its…

Combinatorics · Mathematics 2017-10-12 Amin Bahmanian

We consider edge decompositions of the $n$-dimensional hypercube $Q_n$ into isomorphic copies of a given graph $H$. While a number of results are known about decomposing $Q_n$ into graphs from various classes, the simplest cases of paths…

Combinatorics · Mathematics 2021-01-26 Maria Axenovich , David Offner , Casey Tompkins

A \emph{locally irregular graph} is a graph whose adjacent vertices have distinct degrees. We say that a graph $G$ can be decomposed into $k$ locally irregular subgraphs if its edge set may be partitioned into $k$ subsets each of which…

Combinatorics · Mathematics 2017-03-02 Jakub Przybyło
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