منابع مشابه
Large 2-transitive arcs
The projective planes of order n with a collineation group acting 2-transitively on an arc of length v, with n > v n/2, are investigated and several new examples are provided. © 2006 Elsevier Inc. All rights reserved.
متن کاملNew Large (n, r)-arcs in PG(2, q)
An $(n, r)$-arc is a set of $n$ points of a projective plane such that some $r$, but no $r+1$ of them, are collinear. The maximum size of an $(n, r)$-arc in $PG(2, q)$ is denoted by $m_r(2,q)$. In this paper we present a new $(184,12)$-arc in PG$(2,17),$ a new $(244,14)$-arc and a new $(267,15$)-arc in $PG(2,19).$
متن کاملTransitive Arcs in Planes of Even Order
When one considers the hyperovals in PG (2 , q ) , q even , q . 2 , then the hyperoval in PG (2 , 4) and the Lunelli – Sce hyperoval in PG (2 , 16) are the only hyperovals stabilized by a transitive projective group [10] . In both cases , this group is an irreducible group fixing no triangle in the plane of the hyperoval , nor in a cubic extension of that plane . Using Hartley’s classification ...
متن کاملDisimplicial arcs, transitive vertices, and disimplicial eliminations
In this article we deal with the problems of finding the disimplicial arcs of a digraph and recognizing some interesting graph classes defined by their existence. A diclique of a digraph is a pair V → W of sets of vertices such that v → w is an arc for every v ∈ V and w ∈W . An arc v → w is disimplicial when N−(w)→ N(v) is a diclique. We show that the problem of finding the disimplicial arcs is...
متن کاملArcs with Large Conical Subsets
We classify the arcs in PG(2, q), q odd, which consist of (q + 3)/2 points of a conic C and two points not on te conic but external to C, or (q + 1)/2 points of C and two additional points, at least one of which is an internal point of C. We prove that for arcs of the latter type, the number of points internal to C can be at most 4, and we give a complete classification of all arcs that attain ...
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ژورنال
عنوان ژورنال: Journal of Combinatorial Theory, Series A
سال: 2007
ISSN: 0097-3165
DOI: 10.1016/j.jcta.2006.10.008