The University College London (UCL) Combinatorics Seminar is held every Monday at 4–5pm during term time.

The venue for seminars this term is Room 346 at the SSEES Bulding, 14–16 Taviton Street.

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Next Speaker

• 24th November 2025 - Katherine Staden (Open University)

  Rainbow subgraphs of star-coloured graphs

  
  

  An edge-colouring of a graph $G$ can fail to be rainbow for two reasons: either it contains a monochromatic cherry (a pair of incident edges), or a monochromatic matching of size two. A colouring is a proper colouring if it forbids the first structure, and a star-colouring if it forbids the second structure. I will talk about the problem of determining the maximum number of colours in a star-colouring of a large complete graph which does not contain a rainbow copy of a given graph $H$. This problem is a special case of one studied by Axenovich and Iverson on generalised Ramsey numbers.

  Joint work with Allan Lo, Klas Markström, Dhruv Mubayi, Maya Stein and Lea Weber