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Selflessness, MIF and opposition in groups acting on exotic buildings
Abstract
We prove that groups acting freely and cocompactly on (possibly exotic) affine buildings of type Ã2 and C̃2 are mixed-identity free and have selfless reduced C*-algebras. These results follow from a strong form of ping-pong dynamics that we call 'transversal contractivity'. Our main geometric result regards domesticity properties of elements in the associated polygons at infinity: we prove that, in our context, the opposite geometry of a hyperbolic element is topologically large.
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BibTeX
@misc{bars2026selflessness,
title = {{Selflessness, MIF and opposition in groups acting on exotic buildings}},
author = {Corentin Le Bars and Elyasheev Leibtag and Itamar Vigdorovich},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.17129},
eprint = {2609.17129},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.17129},
}
RIS
TY - UNPB
TI - Selflessness, MIF and opposition in groups acting on exotic buildings
AU - Corentin Le Bars
AU - Elyasheev Leibtag
AU - Itamar Vigdorovich
PY - 2026
DA - 2026/09/15
PB - arXiv
DO - 10.48550/arxiv.2609.17129
UR - https://arxiv.org/abs/2609.17129
AB - We prove that groups acting freely and cocompactly on (possibly exotic) affine buildings of type Ã_2 and C̃_2 are mixed-identity free and have selfless reduced C^*-algebras. These results follow from a strong form of ping-pong dynamics that we call 'transversal contractivity'. Our main geometric result regards domesticity properties of elements in the associated polygons at infinity: we prove that, in our context, the opposite geometry of a hyperbolic element is topologically large.
ER -