The fourth international workshop on Pomsets and Related Structures took place in Rzeszów 8 -- 12 July 2026.
The workshop is associated with the (i)Po(m)set Project, a research project at the crossroads of concurrency theory, automata theory, algebra, and geometry. This fourth edition follows RaPS workshops held in Rennes in April 2024, in Rzeszów in June 2025, and in Paris in September 2025.