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math.CO2025
A note on the classification of classical distance-regular graphs of negative type and the non-existence of hemisystems
Sam Adriaensen, Jan De Beule, Jozefien D'haeseleer +1
DISCLAIMER: Due to an error in the literature, we cannot be sure that the conclusions drawn in this paper are correct. The goal of this note is to connect some interesting results…
math.CO2025
The largest sets of non-opposite chambers in spherical buildings of type
Jan De Beule, Philipp Heering, Sam Mattheus +1
The investigation into large families of non-opposite flags in finite spherical buildings has been a recent addition to a long line of research in extremal combinatorics, extending…
math.CO2025
Strongly regular graphs from hyperbolic quadrics and their maximal cliques
Antonio Cossidente, Jan De Beule, Giuseppe Marino +2
Let be a hyperbolic quadric of $\PG(2n+1,q)$. Fix a generator of the quadric. Define $\cG_n$ as the graph with as vertex set the points of $Q^+(2n+1,q)\setminus Π…