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20112026
most citedFixed point theorem for reflexive Banach spaces and uniformly convex non positively curved metric spaces

7 citations · 31 across the 23 of their papers we have counts for

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10 papers · 1 filter

math.CO2025

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…

math.CO2025

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…

math.CO2024

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…

math.CO2019

Coboundary and cosystolic expansion from strong symmetry

Tali Kaufman, Izhar Oppenheim

Coboundary and cosystolic expansion are notions of expansion that generalize the Cheeger constant or edge expansion of a graph to higher dimensions. The classical Cheeger inequalit…

math.CO2018

Local Spectral Expansion Approach to High Dimensional Expanders Part II: Mixing and Geometrical overlapping

Izhar Oppenheim

In this paper, we further explore the local-to-global approach for expansion of simplicial complexes that we call local spectral expansion. Specifically, we prove that local expans…

math.CO2017

High dimensional expanders and coset geometries

Tali Kaufman, Izhar Oppenheim

High dimensional expanders is a vibrant emerging field of study. Nevertheless, the only known construction of bounded degree high dimensional expanders is based on Ramanujan comple…

math.CO2017

Local spectral expansion approach to high dimensional expanders part I: Descent of spectral gaps

Izhar Oppenheim

This paper introduces the notion of local spectral expansion of a simplicial complex as a possible analogue of spectral expansion defined for graphs. We then show that the conditio…

math.CO2017

High Order Random Walks: Beyond Spectral Gap

Tali Kaufman, Izhar Oppenheim

We study high order random walks in high dimensional expanders; namely, in complexes which are local spectral expanders. Recent works have studied the spectrum of high order walks…

math.CO2015★ 2 cited

Isoperimetric Inequalities and topological overlapping for quotients of Affine buildings

Izhar Oppenheim

We prove isoperimetric inequalities for quotients of -dimensional Affine buildings. We use these inequalities to prove topological overlapping for the 2-dimensional skeletons of…

math.CO2014★ 4 cited

Local spectral expansion approach to high dimensional expanders

Izhar Oppenheim

This paper introduces the notion of local spectral expansion of a simplicial complex as a possible analogue of spectral expansion defined for graphs. We show the condition of local…