We prove that there are $O(m^{2/3}k^{2/3}n^{(d-2)/3} + kn^{d-2})$ incidences
between $k$ red points and $m$ hyperplanes that are determined jointly by the
red points and $n-k$ blue points. This is a generalization of an incidence
bound proved by Agarwal and Aronov \cite{AA92} (i.e., when $k=n$). We provide
an explicit construction that attains the asymptotic result, showing that the
bound is tight.
An algorithm is demonstrated that finds an ordinary intersection in an
arrangement of $n$ lines in $\mathbb{R}^2$, not all parallel and not all
passing through a common point, in time $O(n \log{n})$. The algorithm is then
extended to find an ordinary intersection among an arrangement of hyperplanes
in $\mathbb{R}^d$, no $d$ passing through a line and not all passing through
the same point, again, in time $O(n \log{n})$.
Two additional algorithms are provided that find an ordinary or monochromatic
intersection, respectively, in an arrangement of pseudolines in time $O(n^2)$.