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  1. Home > Articles & Issues >
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  3. On minimal blocking ...
Conference paper

On minimal blocking sets of the generalized quadrangle $Q(4, q)$

Miroslava Cimráková (1), Veerle Fack (1)
(1) Research Group on Combinatorial Algorithms and Algorithmic Graph Theory
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Imported on
May 10, 2017
Published on
December 31, 2004
Last modified on
March 31, 2025
Volume 0
DMTCS Proceedings vol. AE, European Conference on Combinatorics, Graph Theory and Applications (EuroComb '05)
Proceedings
DOI
10.46298/dmtcs.3466
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https://about.hal.science/hal-authorisation-v1
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On minimal blocking sets of the generalized quadrangle $Q(4, q)$

Miroslava Cimráková (1), Veerle Fack (1)
(1) Research Group on Combinatorial Algorithms and Algorithmic Graph Theory
Abstract
The generalized quadrangle $Q(4,q)$ arising from the parabolic quadric in $PG(4,q)$ always has an ovoid. It is not known whether a minimal blocking set of size smaller than $q^2 + q$ (which is not an ovoid) exists in $Q(4,q)$, $q$ odd. We present results on smallest blocking sets in $Q(4,q)$, $q$ odd, obtained by a computer search. For $q = 5,7,9,11$ we found minimal blocking sets of size $q^2 + q - 2$ and we discuss their structure. By an exhaustive search we excluded the existence of a minimal blocking set of size $q^2 + 3$ in $Q(4,7)$.
Keywords
  • [INFO.INFO-DM]Computer Science [cs]/Discrete Mathematics [cs.DM]
  • [MATH.MATH-CO]Mathematics [math]/Combinatorics [math.CO]
  • generalized quadrangle
  • blocking set
  • search algorithm
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