S. Rottey

activity

20122015

collaborators

9 papers

math.CO2015

A geometric characterisation of Desarguesian spreads

Sara Rottey, John Sheekey

We provide a characterisation of $(n - 1)$ -spreads in $PG (r n - 1, q)$ that have $r$ normal elements in general position. In the same way, we obtain a geometric characterisation…

math.CO2015

Unitals with many Baer secants through a fixed point

Sara Rottey, Geertrui Van de Voorde

We show that a unital $U$ in $PG (2, q^{2})$ containing a point $P$ , such that at least $q^{2} - ε$ of the secant lines through $P$ intersect $U$ in a Baer subline, is an ovoidal…

math.CO2015

Characterisations of elementary pseudo-caps and good eggs

Sara Rottey, Geertrui Van de Voorde

In this note, we use the theory of Desarguesian spreads to investigate good eggs. Thas showed that an egg in $PG (4 n - 1, q)$ , $q$ odd, with two good elements is elementary.…

math.CO2014

Identifying codes in vertex-transitive graphs and strongly regular graphs

Sylvain Gravier, Aline Parreau, Sara Rottey +2

We consider the problem of computing identifying codes of graphs and its fractional relaxation. The ratio between the size of optimal integer and fractional solutions is between 1…

math.CO2014

Subgeometries in the André/Bruck-Bose representation

Sara Rottey, John Sheekey, Geertrui Van de Voorde

We consider the André/Bruck-Bose representation of the projective plane $PG (2, q^{n})$ in $PG (2 n, q)$ . We investigate the representation of $F_{q^{k}}$ -subline…

math.CO2014

Pseudo-ovals in even characteristic and ovoidal Laguerre planes

Sara Rottey, Geertrui Van de Voorde

Pseudo-arcs are the higher dimensional analogues of arcs in a projective plane: a pseudo-arc is a set $A$ of $(n - 1)$ -spaces in $PG (3 n - 1, q)$ such that any three s…

math.CO2014

Linear representations of subgeometries

Stefaan De Winter, Sara Rottey, Geertrui Van de Voorde

The linear representation $T_{n}^{*} (K)$ of a point set $K$ in a hyperplane of $PG (n + 1, q)$ is a point-line geometry embedded in this projective space. In t…

math.CO2013

A construction for infinite families of semisymmetric graphs revealing their full automorphism group

Philippe Cara, Sara Rottey, Geertrui Van de Voorde

We give a general construction leading to different non-isomorphic families $Γ_{n,q}(\K)$ of connected $q$ -regular semisymmetric graphs of order $2 q^{n + 1}$ embedded in $\PG(n+1,q)$…

math.CO2012

The isomorphism problem for linear representations and their graphs

Philippe Cara, Sara Rottey, Geertrui Van de Voorde

In this paper, we study the isomorphism problem for linear representations. A linear representation Tn*(K) of a point set K is a point-line geometry, embedded in a projective space…