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Polycyclic Configuration


A configuration is polycyclic if it has a nonidentity automorphism such that the cyclic group it generates has a semiregular group action on the points and lines, so that all point and line orbits have the same size. If the automorphism has order k, the configuration is called k-cyclic (Boben and Pisanski 2003).

Equivalently, the Levi graph of a polycyclic configuration has an automorphism whose cyclic group acts semiregularly and preserves the two parts of its bipartition. For a geometric configuration, the term polycyclic means that the orbits of the points and lines under the maximal group of rotational symmetries all have the same size; these orbits are called its symmetry classes (Berman et al. 2024).

Some named geometric polycyclic configurations, including the Berman configurations, are summarized below. The rotational order is the common size of the point and line orbits in the displayed realization (Berman et al. 2024, 2025).

The Grünbaum-Rigby configuration and Berman-Gévay-Pisanski configuration are exactly the two geometric polycyclic 21_4 configurations. There are 17 combinatorial polycyclic 21_4 configurations (Berman et al. 2024). The Berman 485 and 966 configurations are 12-cyclic in the realizations summarized here (Berman 2014, Pegg 2023).


See also

Berman Configurations, Berman-Gévay-Pisanski Configuration, Configuration, Cyclic Group, Geometric Realization, Gray Configuration, Grünbaum-Rigby Configuration, Group Orbit, Levi Graph, Semiregular Group Action

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References

Berman, L. W. "Geometric Constructions for Symmetric 6-Configurations." In Rigidity and Symmetry (Eds. R. Connelly, A. Ivić Weiss, and W. Whiteley). New York: Springer, pp. 61-85, 2014. https://doi.org/10.1007/978-1-4939-0781-6_4.Berman, L. W.; Gévay, G.; and Pisanski, T. "On a New (21_4) Polycyclic Configuration." Electron. J. Combin. 31, #P4.54, 2024. https://doi.org/10.37236/12405.Berman, L. W.; Gévay, G.; and Pisanski, T. "Polycyclic Geometric Realizations of the Gray Configuration." Australas. J. Combin. 93, 171-197, 2025. https://ajc.maths.uq.edu.au/pdf/93/ajc_v93_p171.pdf.Boben, M. and Pisanski, T. "Polycyclic Configurations." Europ. J. Combin. 24, 431-457, 2003. https://doi.org/10.1016/S0195-6698(03)00031-3.Pegg, E., Jr. "Mathematical Games: Configurations." Dec. 2023. https://community.wolfram.com/groups/-/m/t/3089201.

Cite this as:

Weisstein, Eric W. "Polycyclic Configuration." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/PolycyclicConfiguration.html

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