4 papers
Non-Abelian expansion of congruence KMS complexes
Izhar Oppenheim, Inga Valentiner-Branth
Coboundary expansion with non-Abelian coefficients is a strong version of high-dimensional expansion for simplicial complexes. One motivation for studying this notion is that it wa…
New cosystolic high-dimensional expanders from KMS groups
Izhar Oppenheim, Inga Valentiner-Branth
Cosystolic expansion is a high-dimensional generalization of the Cheeger constant for simplicial complexes. Originally, this notion was motivated by the fact that it implies the to…
Coboundary expansion of coset complexes
Tali Kaufman, Izhar Oppenheim, Shmuel Weinberger
Coboundary expansion is a high dimensional generalization of the Cheeger constant to simplicial complexes. Originally, this notion was motivated by the fact that it implies topolog…
Property (T) for groups acting on affine buildings
Izhar Oppenheim
We prove that a group acting geometrically on a thick affine building has property (T). A more general criterion for property (T) is given for groups acting on partite complexes.