341 research outputs found
Resolving sets for Johnson and Kneser graphs
A set of vertices in a graph is a {\em resolving set} for if, for
any two vertices , there exists such that the distances . In this paper, we consider the Johnson graphs and Kneser
graphs , and obtain various constructions of resolving sets for these
graphs. As well as general constructions, we show that various interesting
combinatorial objects can be used to obtain resolving sets in these graphs,
including (for Johnson graphs) projective planes and symmetric designs, as well
as (for Kneser graphs) partial geometries, Hadamard matrices, Steiner systems
and toroidal grids.Comment: 23 pages, 2 figures, 1 tabl
Almost simple groups as flag-transitive automorphism groups of 2-designs with {\lambda} = 2
In this article, we study -designs with admitting a
flag-transitive almost simple automorphism group with socle a finite simple
exceptional group of Lie type, and we prove that such a -design does not
exist. In conclusion, we present a classification of -designs with
admitting flag-transitive and point-primitive automorphism groups
of almost simple type, which states that such a -design belongs to an
infinite family of -designs with parameter set and
for some , or it is isomorphic to the -design with
parameter set , , , , ,
, , , or
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