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Archiv der Mathematik

, Volume 78, Issue 2, pp 166–172 | Cite as

A combinatorial characterization of classical unitals

  • A. Aguglia
  • G. L. Ebert

Abstract.

In this paper we give a characterization of classical unitals in terms of a configuration pattern formed by the feet of a unital U embedded in PG(2, q 2), q > 2. We show that a necessary and sufficient condition for U to be classical is the existence of two points \( p_0, p_1 \in U \) with tangent lines L 0 and L 1, respectively, such that for all points \( r \in L_0 \backslash \{p_0\} \) and \( s \in L_1 \backslash \{p_1\} \) the corresponding feet are collinear.

Keywords

Tangent Line Classical Unitals Combinatorial Characterization Configuration Pattern 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Birkhäuser Verlag, Basel 2002

Authors and Affiliations

  • A. Aguglia
    • 1
  • G. L. Ebert
    • 2
  1. 1.Dipartimento di Mat. e Appl., “R. Caccioppoli”, Università di Napoli “Federico II”, 80126 Napoli, Italy, e-mail: aguglia@matna2.dma.unina.itIT
  2. 2.Department of Mathematical Sciences, University of Delaware, Newark, DE 19716, USA,¶ e-mail: ebert@math.udel.eduUS

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