Let Delta be a finite thick dual polar space of rank 3. We say that a hyperplane H of Delta is locally singular (respectively, quadrangular or ovoidal) if H boolean AND Q is the perp of a point (resp. a subquadrangle or an ovoid) of Q for every quad Q of Delta. If H is locally singular, quadrangular, or ovoidal, then we say that H is uniform. It is known that if H is locally singular, then either H is the set of points at non-maximal distance from a given point of Delta or Delta is the dual of L(6, q) and H arises from the generalized hexagon H(q). In this paper we prove that only two examples exist for the locally quadrangular case, arising in L(6, 2) and H (5, 4), respectively. We fail to rule out the locally ovoidal case, but we obtain some partial results on it, which imply that, in this case, the geometry Delta H induced by Delta on the complement of H cannot be flag-transitive. As a bi-product, the hyperplanes H with Delta H flag-transitive are classified. (C) 2001 Academic Press.

Pasini, A., Shpectorov, S.V. (2001). Uniform hyperplanes of finite dual polar spaces of rank 3. JOURNAL OF COMBINATORIAL THEORY. SERIES A, 94(2), 276-288 [10.1006/jcta.2000.3136].

Uniform hyperplanes of finite dual polar spaces of rank 3

PASINI, ANTONIO;
2001-01-01

Abstract

Let Delta be a finite thick dual polar space of rank 3. We say that a hyperplane H of Delta is locally singular (respectively, quadrangular or ovoidal) if H boolean AND Q is the perp of a point (resp. a subquadrangle or an ovoid) of Q for every quad Q of Delta. If H is locally singular, quadrangular, or ovoidal, then we say that H is uniform. It is known that if H is locally singular, then either H is the set of points at non-maximal distance from a given point of Delta or Delta is the dual of L(6, q) and H arises from the generalized hexagon H(q). In this paper we prove that only two examples exist for the locally quadrangular case, arising in L(6, 2) and H (5, 4), respectively. We fail to rule out the locally ovoidal case, but we obtain some partial results on it, which imply that, in this case, the geometry Delta H induced by Delta on the complement of H cannot be flag-transitive. As a bi-product, the hyperplanes H with Delta H flag-transitive are classified. (C) 2001 Academic Press.
2001
Pasini, A., Shpectorov, S.V. (2001). Uniform hyperplanes of finite dual polar spaces of rank 3. JOURNAL OF COMBINATORIAL THEORY. SERIES A, 94(2), 276-288 [10.1006/jcta.2000.3136].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11365/7073
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