Affiliation:
1. School of Mathematics (Zhuhai) , Sun Yat-sen University , Zhuhai , Guangdong , P. R. China
Abstract
Abstract
In this paper, we investigate various properties of strong and weak twisted Bruhat orders on a Coxeter group.
In particular, we prove that any twisted strong Bruhat order on an affine Weyl group is locally finite, strengthening a result of Dyer [Quotients of twisted Bruhat orders,
J. Algebra 163 1994, 3, 861–879].
We also show that, for a non-finite and non-cofinite biclosed set B in the positive system of an affine root system with rank greater than 2, the set of elements having a fixed B-twisted length is infinite.
This implies that the twisted strong and weak Bruhat orders have an infinite antichain in those cases.
Finally, we show that twisted weak Bruhat order can be applied to the study of the tope poset of an infinite oriented matroid arising from an affine root system.
Funder
Natural Science Foundation of Guangdong Province
Subject
Algebra and Number Theory
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