{ "id": "2209.10863", "version": "v1", "published": "2022-09-22T08:50:03.000Z", "updated": "2022-09-22T08:50:03.000Z", "title": "On the Equivalence, Stabilisers, and Feet of Buekenhout-Tits Unitals", "authors": [ "Jake Faulkner", "Geertrui Van de Voorde" ], "categories": [ "math.CO" ], "abstract": "This paper addresses a number of problems concerning Buekenhout-Tits unitals in $PG(2,q^2)$, where $q = 2^{e+1}$ and $e \\geq 1$. We show that all Buekenhout-Tits unitals are $PGL$-equivalent (addressing an open problem in [S. Barwick and G. L. Ebert. Unitals in projective planes. Springer Monographs in Mathematics. Springer, New York, 2008.]), explicitly describe their $P\\Gamma L$-stabiliser (expanding Ebert's work in [G.L. Ebert. Buekenhout-Tits unitals. J. Algebraic. Combin. 6.2 (1997), 133-140], and show that lines meet the feet of points no on $\\ell_\\infty$ in at most four points. Finally, we show that feet of points not on $\\ell_\\infty$ are not always a $\\{0,1,2,4\\}$-set, in contrast to what happens for Buekenhout-Metz unitals [N. Abarz\\'ua, R. Pomareda, and O. Vega. Feet in orthogonal-Buekenhout-Metz unitals. Adv. Geom. 18.2 (2018), 229-236].", "revisions": [ { "version": "v1", "updated": "2022-09-22T08:50:03.000Z" } ], "analyses": { "keywords": [ "stabiliser", "equivalence", "problems concerning buekenhout-tits unitals", "expanding eberts work", "springer monographs" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }