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Let $F$ be a $2$-regular graph of order $v$. The Oberwolfach problem $OP(F)$, posed in 1967 and still open, asks for a decomposition of $K_v$ into copies of $F$. In this paper we show that $OP(F)$ has a solution whenever $F$ has a…

Combinatorics · Mathematics 2023-05-18 A. C. Burgess , P. Danziger , T. Traetta

The Oberwolfach Problem $OP(F)$ -- posed by Gerhard Ringel in 1967 -- is a paradigmatic Combinatorial Design problem asking whether the complete graph $K_v$ decomposes into edge-disjoint copies of a $2$-regular graph $F$ of order $v$. In…

Combinatorics · Mathematics 2021-11-17 Fabio Salassa , Gabriele Dragotto , Tommaso Traetta , Marco Buratti , Federico Della Croce

Let $F$ be a $2$-regular graph of order $v$. The Oberwolfach problem, $OP(F)$, asks for a $2$-factorization of the complete graph on $v$ vertices in which each $2$-factor is isomorphic to $F$. In this paper, we give a complete solution to…

Combinatorics · Mathematics 2019-08-15 Simone Costa

The Oberwolfach problem, posed by Ringel in 1967, asks for a decomposition of $K_{2n+1}$ into edge-disjoint copies of a given $2$-factor. We show that this can be achieved for all large $n$. We actually prove a significantly more general…

Combinatorics · Mathematics 2021-02-12 Stefan Glock , Felix Joos , Jaehoon Kim , Daniela Kühn , Deryk Osthus

The generalized Oberwolfach problem asks for a decomposition of a graph $G$ into specified 2-regular spanning subgraphs $F_1,\ldots, F_k$, called factors. The classic Oberwolfach problem corresponds to the case when all of the factors are…

Combinatorics · Mathematics 2023-08-09 Andrea Burgess , Peter Danziger , Tommaso Traetta

The Directed Oberwolfach Problem can be considered as the directed version of the well-known Oberwolfach Problem, first mentioned by Ringel at a conference in Oberwolfach, Germany in 1967. In this paper, we describe some new partial results…

Combinatorics · Mathematics 2020-09-21 Elaheh Shabani , Mateja Šajna

The Oberwolfach problem asks for a $2$-factorization of the complete graph in which each $2$-factor is isomorphic to a specific factor $F$. Recently, this problem has been extended to directed graphs. In this case, the directed Oberwolfach…

Combinatorics · Mathematics 2026-02-20 A. C. Burgess , P. H. Danziger , A. Lacaze-Masmonteil

The directed Oberwolfach problem OP$^\ast(m_1,\ldots,m_k)$ asks whether the complete symmetric digraph $K_n^\ast$, assuming $n=m_1+\ldots +m_k$, admits a decomposition into spanning subdigraphs, each a disjoint union of $k$ directed cycles…

Combinatorics · Mathematics 2024-09-04 Suzan Kadri , Mateja Šajna

Various results on factorisations of complete graphs into circulant graphs and on 2-factorisations of these circulant graphs are proved. As a consequence, a number of new results on the Oberwolfach Problem are obtained. For example, a…

Combinatorics · Mathematics 2014-11-25 Brian Alspach , Darryn Bryant , Daniel Horsley , Barbara Maenhaut , Victor Scharaschkin

The generalization of the Oberwolfach Problem, proposed by J. Liu in 2000, asks for a uniform $2$-factorization of the complete multipartite graph $K_{m\times n}$. Here we focus our attention on $2$-factorizations regular under the cyclic…

Combinatorics · Mathematics 2016-03-22 Anita Pasotti , Marco Antonio Pellegrini

The generalized Oberwolfach problem asks for a factorization of the complete graph $K_v$ into prescribed $2$-factors and at most a $1$-factor. When all $2$-factors are pairwise isomorphic and $v$ is odd, we have the classic Oberwolfach…

Combinatorics · Mathematics 2023-07-24 Peter Danziger , Eric Mendelsohn , Brett Stevens , Tommaso Traetta

We prove that any quasirandom dense large graph in which all degrees are equal and even can be decomposed into any given collection of two-factors (2-regular spanning subgraphs). A special case of this result gives a new solution to the…

Combinatorics · Mathematics 2020-04-22 Peter Keevash , Katherine Staden

The concept of a $1$-rotational factorization of a complete graph under a finite group $G$ was studied in detail by Buratti and Rinaldi. They found that if $G$ admits a $1$-rotational $2$-factorization, then the involutions of $G$ are…

Combinatorics · Mathematics 2018-10-25 Daniel McGinnis , Eirini Poimenidou

In this paper, we give a solution to the last outstanding case of the directed Oberwolfach problem with tables of uniform length. Namely, we address the two-table case with tables of odd length. We prove that the complete symmetric digraph…

Combinatorics · Mathematics 2023-09-08 Alice Lacaze-Masmonteil

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 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 prove that there exists a bivariate function f with f(k,l) = O(l k log k) such that for every naturals k and l, every graph G has at least k vertex-disjoint cycles of length at least l or a set of at most f(k,l) vertices that meets all…

Combinatorics · Mathematics 2012-05-07 Samuel Fiorini , Audrey Herinckx

In 1985, Mader conjectured that for every acyclic digraph $F$ there exists $K=K(F)$ such that every digraph $D$ with minimum out-degree at least $K$ contains a subdivision of $F$. This conjecture remains widely open, even for digraphs $F$…

Combinatorics · Mathematics 2020-09-01 Lior Gishboliner , Raphael Steiner , Tibor Szabó

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 address the last outstanding case of the directed Oberwolfach problem with two tables of different lengths. Specifically, we show that the complete symmetric directed graph $K^*_n$ admits a decomposition into spanning subdigraphs…

Combinatorics · Mathematics 2024-08-21 Daniel Horsley , Alice Lacaze-Masmonteil
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