Grahame Erskine, Terry S. Griggs
Published 2024-01-24Version 1
Properties of the 62,336,617 Steiner triple systems of order 21 with a non-trivial automorphism group are examined. In particular, there are 28 which have no parallel class, six that are 4-chromatic, five that are 3-balanced, 20 that avoid the mitre, 21 that avoid the crown, one that avoids the hexagon and two that avoid the prism. All systems contain the grid. None have a block intersection graph that is 3-existentially closed.
Further Results on Existentially Closed Graphs Arising from Block Designs
Hamiltonicity of $2$-block intersection graphs of ${\rm{TS}}(v,λ)$: $v\equiv 0$ or $4\pmod{12}$
Perfect 1-factorisations of $K_{16}$
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