Abstract
In this paper, we introduce a fundamental substructure of maximal caps in the affine geometry AG(4, 3) that we call demicaps. Demicaps provide a direct link to particular partitions of AG(4, 3) into 4 maximal caps plus a single point. The full collection of 36 maximal caps that are in exactly one partition with a given cap C can be expressed as unions of two disjoint demicaps taken from a set of 12 demicaps; these 12 can also be found using demicaps in C. The action of the affine group on these 36 maximal caps includes actions related to the outer automorphisms of \(S_6\).
Similar content being viewed by others
Data Availability
Not applicable.
Code Availability
Not applicable.
Notes
The lines in a \(3\times 3\) subgrid, also called a plane, are three points horizontally, vertically, or diagonally, including diagonals as on a torus; the points in all other lines appear in three subgrids that are in the same position as a line in the \(3\times 3\) subgrids, so that, when the three subgrids are superimposed, those points either lie on top of one another, or they are in the same positions as a line in a subgrid. See Fig. 1.
References
Awan, J.: Cap builder. http://webbox.lafayette.edu/mcmahone/capbuilder.html
Bierbrauer, J.: Large caps. J. Geom. 76(1–2), 16–51 (2003). (Combinatorics, 2002 (Maratea))
Benjamin Lent Davis and Diane Maclagan: The card game SET. Math. Intell. 25(3), 33–40 (2003)
Edel, Y., Ferret, S., Landjev, I., Storme, L.: The classification of the largest caps in \(\rm AG(5,3)\). J. Combin. Theory Ser. A 99(1), 95–110 (2002)
Ellenberg, J.S., Gijswijt, D.: On large subsets of \(F^n_q\) with no three-term arithmetic progression. Ann. Math. Second Ser. 185(1), 339–343 (2017)
Follett, M., Kalail, K., McMahon, E., Pelland, C., Won, R.: Partitions of \(AG(4,3)\) into maximal caps. Discret. Math. 337, 1–8 (2014)
Hill, R.: On Pellegrino’s $20$-caps in \(S_{4,3}\). In: Combinatorics ’81 (Rome, 1981), vol. 78: North-Holland Math. Stud., pp. 433–447. North-Holland, Amsterdam (1983)
Kestenband, B.C.: Partitions of finite affine geometries into caps. Linear Multilinear Algebra 14(3), 257–270 (1983)
Pellegrino, G.: Sul massimo ordine delle calotte in S4,3. Matematiche (Catania) 25(149–157), 1970 (1971)
Potechin, A.: Maximal caps in AG (6,3). Des. Codes Cryptogr. 46(3), 243–259 (2008)
Rotman, J.J.: An Introduction to the Theory of Groups. Graduate Texts in Mathematics, vol. 148, 4th edn. Springer, New York (1995)
Wolfram Research, Inc: Mathematica, Version 11.3. Champaign, IL (2018)
Funding
Research supported by NSF grant DMS-1063070.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Conflict of interest
The authors have no relevant financial or non-financial interests to disclose.
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
Springer Nature or its licensor holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
About this article
Cite this article
Awan, J., Frechette, C., Li, Y. et al. Demicaps in AG(4,3) and Maximal Cap Partitions. Graphs and Combinatorics 38, 193 (2022). https://doi.org/10.1007/s00373-022-02568-x
Received:
Revised:
Accepted:
Published:
DOI: https://doi.org/10.1007/s00373-022-02568-x