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New Steiner systems from old ones by paramodifications

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arxiv 2003.09233 v2 pith:4FXTZTER submitted 2020-03-20 math.CO

classification math.CO
keywords steinerdesignsclassconstructionmodifiesonesparamodificationparamodifications
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Techniques of producing new combinatorial structures from old ones are commonly called trades. The switching principle applies for a broad class of designs: it is a local transformation that modifies two columns of the incidence matrix. In this paper, we present a construction, which is a generalization of the switching transform for the class of Steiner 2-designs. We call this construction paramodification of Steiner 2-designs, since it modifies the parallelism of a subsystem. We study in more detail the paramodifications of affine planes, Steiner triple systems, and abstract unitals. Computational results show that paramodification can construct many new unitals.

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Cited by 1 Pith paper

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

  1. Point-transitive Steiner systems S(2,6,111/121/126), S(2,7,169/175)

    math.CO 2025-04 conditional novelty 5.0 of 10

    Explicit difference families and block lists are given for new point-transitive Steiner systems S(2,6,111), S(2,6,121), S(2,6,126), S(2,7,169), and S(2,7,175), including an exhaustive count of 30 systems on 111 points.

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