The automorphism group of a complete (q − 1)‐arc in PG(2,q)

The automorphism group of the set of 12 points associated with an apolar system of conics is determined. A complete (q − 1)-arc for q = 13 can be obtained as a special case. The orbits of its automorphism group are also described. © 1994 John Wiley & Sons, Inc.