PhaseC Plenary Talks

On Friday 17 April 2026, Penny Haxell (University of Waterloo) and Rob Morris (IMPA) will give two public lectures as part of the final afternoon of the PhaseC Problem-Solving Workshop within the Research Semester Programme PhaseCAP. You are cordially invited to attend these plenary talks. Attendance is free, but registration is required.

Share this page
When
17 apr 2026 from 2 p.m. to 17 apr 2026 4 p.m. CEST (GMT+0200)
Where
Nikhef Colloquium Room/Auditorium, Science Park 105, Amsterdam
Add
Add event to calendar

PhaseCAP brings together leading researchers in combinatorics, algorithms, and probability to explore how ideas from statistical physics – such as phase transitions, sudden shifts in the behaviour of complex systems – can illuminate fundamental problems in networks, algorithms, and random structures.

While the workshop itself is by invitation only, this public session offers a chance to hear plenary talks by two prominent speakers: Penny Haxell (University of Waterloo) and Rob Morris (IMPA).

The lectures are aimed at researchers and advanced students in mathematics, theoretical computer science, and related fields who are interested in the mathematical foundations of complex systems.

Abstracts

Show

An independent transversal (IT) of a graph G with a given vertex partition P is an independent set in G consisting of one vertex in each of the parts of P. This is a very general notion, and many problems in mathematics can be expressed by asking whether a particular graph G with a particular choice of P has an IT. Various criteria involving properties of G and P are known that will guarantee the existence of an IT in G.

More broadly, one may wish to consider the space of all IT's for a given G and P, and investigate how they are related. For example, under what conditions is this space connected, in the sense that one can transition from any IT to any other via a sequence of single-vertex modifications? It has been shown (Buys-Kang-Ozeki, Wdowinski) that with conditions only very slightly stronger than those ensuring the existence of a single IT, this connectivity property also holds.

Here we consider the algorithmic version of this question, and show that under certain similarly minimal conditions, such reconfiguration paths in the space of all IT's can be found efficiently.

Over the past few years there have been a series of remarkable breakthroughs in graph Ramsey theory. In this talk we will discuss several of these, including exponential improvements for the diagonal, near-diagonal, and multicolor Ramsey numbers, improved lower bounds on R(3,k) and R(4,k), and an exponential upper bound on the induced Ramsey numbers.

Registration

Attendance is free but registration for the PhaseC Lectures is required. Please register until 6 April 2026 or until capacity is reached, whichever is earlier.

Organizers and support

PhaseCAP is organised by CWI, TU Delft, the University of Amsterdam, TU Eindhoven, the University of Groningen, and collaborating institutions. The programme is supported by the Dutch Ministry of Education, Culture and Science (OCW), NWO, the 4TU+AMI Strategic Research Initiative, and the Korteweg–de Vries Institute for Mathematics.