Bijections for hyperplane arrangements of Coxeter type
CMSA COLLOQUIUM
When: February 2, 2026
4:30 pm - 5:30 pm
Where: CMSA, 20 Garden St, G10
Address:
20 Garden Street, Cambridge, MA 02138, United States
Speaker: Olivier Bernardi (Brandeis University)
This talk is about real hyperplane arrangements whose hyperplanes are of the form {xi −xj = s} or {xi +xj = s}. We describe a bijective framework for a large family of such arrangements which we call transitive. For each transitive arrangement A, we give a bijection between the regions of A and a set of decorated trees. Particular cases include the families of Catalan, Shi, semiorder and Linial arrangements in type A, B, C, D and BC. We also derive some general enumerative formulas for such families of transitive arrangements.
