2 research outputs found
On line covers of finite projective and polar spaces
An - of lines of a finite projective space (of a
finite polar space ) is a set of lines of (of
) such that every point of (of ) contains
lines of , for some . Embed in .
Let denote the set of points of lying on the
extended lines of .
An -cover of is an -dual -cover if
there are two possibilities for the number of lines of contained in an
-space of . Basing on this notion, we characterize
-covers of such that is a
two-character set of . In particular, we show that if
is invariant under a Singer cyclic group of then it is an
-dual -cover.
Assuming that the lines of are lines of a symplectic polar space
(of an orthogonal polar space of parabolic
type), similarly to the projective case we introduce the notion of an
-dual -cover of symplectic type (of parabolic type). We prove that an
-cover of (of ) has this dual
property if and only if is a tight set of an Hermitian variety
or of (of or of ). We also provide some interesting examples of -dual
-covers of symplectic type of .Comment: 20 page