twinned conferences

I am an active proponent and co-organizer of twinned conferences (previously called double conferences), a new eco-friendly conference format whose purpose is to reduce long-distance travel while still fostering long-distance interactions. Events take place in two different locations connected by live video stream.

To my knowledge, there have been four twinned conferences so far (but please let me know of any others!). I was a co-organizer for the first three.

1. The first twinned conference was held in August 2018, entitled Higher algebra and mathematical physics and co-hosted by the Perimeter Institute for Mathematical Physics (Waterloo, Canada) and the Max Planck Institute for Mathematics (Bonn, Germany); you can find the conference websites here and here.

   You can read a write-up of our experience organizing this event on page 32 of this issue of the London Mathematical Society newsletter.

2. The second twinned conference was held in June 2020, entitled Geometric representation theory and co-hosted by the same two institutions; you can find the conference websites here and here. However, due to the global pandemic, it was moved entirely online.

   Ben Webster (one of the co-organizers) wrote a succinct summary of the lessons we learned regarding online conferences, which you can read as a tweetstorm here.

3. The third twinned conference (and the first one to be called that instead of a "double conference") was held in June 2022, entitled Homotopy theory with applications to arithmetic and geometry and co-hosted by the Fields Institute (Toronto, Canada) and the Max Planck Institute for Mathematics (Bonn, Germany); you can find the conference websites here and here.

4. The fourth twinned conference was held in June & July 2025, entitled Quantum field theory and topological phases via homotopy theory and operator algebras and co-hosted by Harvard's Center of Mathematical Sciences and Applications (Cambridge, Massachusetts, USA) and the Max Planck Institute for Mathematics (Bonn, Germany); you can find the conference websites here and here.