摘要

Let D be a nontrivial triplane, and G be a subgroup of the full automorphism group of D. In this paper we prove that if D is a triplane, G <= Aut (D) is flag-transitive, point-primitive and Soc(G) is an alternating group, then D is the projective space PG(2)(3, 2), and G congruent to Lambda(7) with the point stabiliser G(x) congruent to PSL(3)(2).