activity
20242026
collaborators

6 papers

math.CO2026

Beyond Nash-Williams: Counterexamples to Clique Decomposition Thresholds for All Cliques Larger than Triangles

Michelle Delcourt, Cicely Henderson, Thomas Lesgourgues +1

A central open question in extremal design theory is Nash-Williams' Conjecture from 1970 that every -divisible graph on vertices (for large enough) with minimum degree…

math.CO2025

Odd-Ramsey numbers of Hamilton cycles

Simona Boyadzhiyska, Shagnik Das, Thomas Lesgourgues +1

The odd-Ramsey number of a graph , as introduced by Alon in his work on graph-codes, is the minimum number of colours needed to edge-colour so that ev…

math.CO2025

Fractional Clique Decompositions of Dense Hypergraphs

Michelle Delcourt, Thomas Lesgourgues, Luke Postle

In 2014, Keevash famously proved the existence of -Steiner systems as part of settling the Existence Conjecture of Combinatorial Designs (dating from the mid-1800s). In 20…

math.CO2025

Erdős meets Nash-Williams

Michelle Delcourt, Cicely, Henderson +2

In 1847, Kirkman proved that there exists a Steiner triple system on vertices (equivalently a triangle decomposition of the edges of ) whenever satisfies the necessary…

math.CO2025

Ramsey with purple edges

Thomas Lesgourgues, Anita Liebenau, Nye Taylor

Motivated by a question of Angell, we investigate a variant of Ramsey numbers where some edges are coloured simultaneously red and blue, which we call purple. Specifically, we are…

math.CO2024

Odd-Ramsey numbers of complete bipartite graphs

Simona Boyadzhiyska, Shagnik Das, Thomas Lesgourgues +1

In his study of graph codes, Alon introduced the concept of the odd-Ramsey number of a family of graphs in , defined as the minimum number of colours needed to c…