An affine spread is a set of subspaces of $$\textrm{AG}(n, q)$$
AG
(
n
,
q
)
of the same dimension that partitions the points of $$\textrm{AG}(n, q)$$
AG
(
n
,
q
)
. Equivalently, an affine spread is a set of projective subspaces of $$\textrm{PG}(n, q)$$
PG
(
n
,
q
)
of the same dimension which partitions the points of $$\textrm{PG}(n, q) \setminus H_{\infty }$$
PG
(
n
,
q
)
\
H
∞
; here $$H_{\infty }$$
H
∞
denotes the hyperplane at infinity of the projective closure of $$\textrm{AG}(n, q)$$
AG
(
n
,
q
)
. Let $$\mathcal {Q}$$
Q
be a non-degenerate quadric of $$H_\infty $$
H
∞
and let $$\Pi $$
Π
be a generator of $$\mathcal {Q}$$
Q
, where $$\Pi $$
Π
is a t-dimensional projective subspace. An affine spread $$\mathcal {P}$$
P
consisting of $$(t+1)$$
(
t
+
1
)
-dimensional projective subspaces of $$\textrm{PG}(n, q)$$
PG
(
n
,
q
)
is called hyperbolic, parabolic or elliptic (according as $$\mathcal {Q}$$
Q
is hyperbolic, parabolic or elliptic) if the following hold:
Each member of $$\mathcal {P}$$
P
meets $$H_\infty $$
H
∞
in a distinct generator of $$\mathcal {Q}$$
Q
disjoint from $$\Pi $$
Π
;
Elements of $$\mathcal {P}$$
P
have at most one point in common;
If $$S, T \in \mathcal {P}$$
S
,
T
∈
P
, $$|S \cap T| = 1$$
|
S
∩
T
|
=
1
, then $$\langle S, T \rangle \cap \mathcal {Q}$$
⟨
S
,
T
⟩
∩
Q
is a hyperbolic quadric of $$\mathcal {Q}$$
Q
.
In this note it is shown that a hyperbolic, parabolic or elliptic affine spread of $$\textrm{PG}(n, q)$$
PG
(
n
,
q
)
is equivalent to a spread of $$\mathcal {Q}^+(n+1, q)$$
Q
+
(
n
+
1
,
q
)
, $$\mathcal {Q}(n+1, q)$$
Q
(
n
+
1
,
q
)
or $$\mathcal {Q}^-(n+1, q)$$
Q
-
(
n
+
1
,
q
)
, respectively.