engleski

Flag-transitive and point-imprimitive symmetric designs with λ≤10

In a paper published in 2005, Praeger and Zhou improved the upper bound on the number of points of a flag-transitive, point-imprimitive, symmetric design in terms of the number of blocks containing two points. Here we present an improvement of their result, devise a list of feasible parameter sequences for which two points are contained in at most ten blocks, and also develop new methods for the elimination of all but two such sequences. We used those methods to list all designs with given properties, with the exclusion of designs with said two sets of parameters for which we give limitations for their group of automorphisms.

Symmetric designs ; Point-imprimitive designs ; Flag-transitive designs ; Automorphism groups

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