This area studies when a large host graph or hypergraph must contain a given spanning subgraph, such as a Hamilton cycle, a perfect tiling, a spanning surface, or a more general spanning structure. The central question is which easily checkable density conditions, such as minimum degree, force this structure to appear.
My work takes place mostly in the hypergraph setting, including tight and loose Hamilton cycles, combinatorial spheres and perfect tilings. A recurring theme is to develop notions of robustness that directly connect abstract necessary conditions that certify lower bounds with the existence of the desired object. Once such a framework is obtained, many concrete problems can be solved with ease.
With A. Müyesser, M. Schacht, C. Schildkraut,
Dirac subgraphs of powers of cycles are Hamiltonian,
preprint (2026), 32 pages.
With J. Allsop, A. Lamaison and S. Rathke,
Spanning Components and Surfaces Under Minimum Vertex Degree,
preprint (2025), 15 pages.
With N. Sanhueza-Matamala,
Loose Hamiltonicity,
preprint (2025), 23 pages.
With N. Sanhueza-Matamala,
A hypergraph bandwidth theorem,
preprint (2024), 45 pages.
With M. Schacht and J. Volec,
Tight Hamiltonicity from dense links of triples,
preprint (2024), 17 pages.
With F. Joos and N. Sanhueza-Matamala,
Robust Hamiltonicity,
preprint (2023), 30 pages.
With J. D. Alvarado, Y. Kohayakawa, G. O. Mota and H. Stagni,
Resilience for Loose Hamilton Cycles,
preprint (2023), 33 pages.
Tiling dense hypergraphs,
preprint (2023), 45 pages.
With N. Sanhueza-Matamala,
Blowing up Dirac's theorem,
Bulletin of the London Mathematical Society (2026), 16 pages.
With H. Hàn, J. Pedro Marciano, M. Pavez-Signé, N. Sanhueza-Matamala, A. Treglown and C. Zárate-Guerén,
Colour-bias perfect matchings in hypergraphs,
SIAM Journal on Discrete Mathematics (2025), 22 pages.
With F. Illingworth, A. Müyesser, O. Parczyk and A. Sgueglia,
Spanning spheres in Dirac hypergraphs,
Combinatorica (2025), 29 pages.
With E. Hurley and F. Joos,
Sufficient conditions for perfect mixed tilings,
Journal of Combinatorial Theory, Series B (2024), 60 pages.
With N. Sanhueza-Matamala,
On sufficient conditions for spanning structures in dense graphs,
Proceedings of the London Mathematical Society (2023), 83 pages.
With N. Sanhueza-Matamala,
Minimum degree conditions for tight Hamilton cycles,
Journal of the London Mathematical Society (2022), 75 pages.
This area studies how the edge set of a graph can be split into well-structured parts. Central questions concern the possibility of decomposing a (hyper)graph into rigid parts, or the optimal number of parts when the objects are more flexible. A typical problem from the latter line of research is to colour the edges of a graph with few colours so that no two conflicting edges receive the same colour. The guiding question is how far the trivial lower bounds, usually arising from the maximum degree or other local constraints, are from the true answer.
My work establishes improved bounds for related problems, including local list edge-colouring, simultaneous edge-colouring and linear arboricity. While my earlier work focuses on structural analysis involving parameters such as treewidth, my recent work has shifted more towards a probabilistic toolset, which allows these problems to be resolved in large systems.
With S. Boyadzhiyska, A. Lo and M. Molloy
Simultaneous edge-colourings,
preprint (2024), 14 pages.
With M. Bonamy, M. Delcourt and L. Postle,
Edge-colouring graphs with local list sizes
Journal of Combinatorial Theory, Series B (2024), 28 pages.
With L. Postle,
An Improved Bound for the Linear Arboricity Conjecture,
Combinatorica (2023), 22 pages.
With H. Bruhn and L. Gellert,
Chromatic index, treewidth and maximum degree,
Electronic Journal of Combinatorics (2018), 14 pages.
With H. Bruhn and M. Stein,
List edge-colouring and total colouring in graphs of low treewidth,
Journal of Graph Theory (2018), 10 pages.
A Note on Total and List Edge-Colouring of Graphs of Tree-Width 3,
Graphs and Combinatorics (2015), 10 pages.
This area studies the phenomenon that any colouring of a sufficiently large structure must contain a well-structured monochromatic part. A classic example is Ramsey's theorem, which in its simplest case tells us that among six people there is always a set of three mutual friends or three mutual strangers.
Much of my work concerns a partitioning variant of this theme. Given an edge-coloured graph, the goal is to cover its vertex set with as few monochromatic pieces, usually cycles and paths, as possible. The guiding question is how this number depends on the number of colours and whether it can be bounded independently of the size of the graph. The methods involved often combine tools from extremal combinatorics, such as the regularity lemma and absorption, with careful structural analysis.
With G. O. Mota
Monochromatic cycle partitions in 3-mean edge-colourings,
preprint (2026), 11 pages.
With P. Allen, J. Böttcher, J. Skokan and M. Stein,
Partitioning a 2-edge-coloured graph of minimum degree 2n/3 + o(n) into three monochromatic cycles,
European Journal of Combinatorics (2023), 30 pages.
With D. Korándi, S. Letzter and A. Pokrovskiy,
Minimum degree conditions for monochromatic cycle partitioning,
Journal of Combinatorial Theory, Series B (2021), 27 pages.
With A. Lo,
Monochromatic cycle partitions in random graphs,
Combinatorics, Probability and Computing (2020), 16 pages.
With J. Corsten, L. DeBiasio and A. Lamaison,
Upper density of monochromatic infinite paths,
Advances in Combinatorics (2019), 16 pages.
With O. Schaudt and M. Stein,
Almost partitioning a 3-edge-coloured K_{n,n} into 5 monochromatic cycles,
SIAM Journal of Discrete Mathematics (2017), 28 pages.
With M. Stein,
Local colourings and monochromatic partitions in complete bipartite graphs,
European Journal of Combinatorics (2017), 12 pages.