Finite quotients of Bruhat–Tits buildings as geometric expanders

Shai Evra
2017 Journal of Topology and Analysis (JTA)  
In FGLNP, Fox, Gromov, Lafforgue, Naor and Pach, in a respond to a question of Gromov G, constructed bounded degree geometric expanders, namely, simplical complexes having the affine overlapping property. Their explicit constructions are finite quotients of Ã_̃d̃-buildings, for d≥ 2, over local fields. In this paper, this result is extended to general high rank Bruhat-Tits buildings.
doi:10.1142/s1793525317500078 fatcat:7afhk77lsbcitkyiysxiiuulvu