2 research outputs found
Distance-regular graphs
This is a survey of distance-regular graphs. We present an introduction to
distance-regular graphs for the reader who is unfamiliar with the subject, and
then give an overview of some developments in the area of distance-regular
graphs since the monograph 'BCN' [Brouwer, A.E., Cohen, A.M., Neumaier, A.,
Distance-Regular Graphs, Springer-Verlag, Berlin, 1989] was written.Comment: 156 page
Relative symplectic subquadrangle hemisystems of the Hermitian surface
We introduce the notion of relative subquadrangle regular system of a generalized quadrangle. A relative subquadrangle regular system of order m on a generalized quadrangle S of order (s, t) is a set R of embedded subquadrangles with a prescribed intersection prop- erty with respect to a given subquadrangle T such that every point of S \ T lies on exactly m subquadrangles of R. If m is one half of the total number of such subquadrangles on a point we call R a relative subquadrangle hemisystem with respect to T . We construct two infinite families of symplectic relative subquadrangle hemisystems of the Hermitian surface H(3,q2), q even