We prove that any real matrix $A$ contains a subset of at most
$4k/\eps + 2k \log(k+1)$ rows whose span ``contains" a matrix of
rank at most $k$ with error only $(1+\eps)$ times the error of the
best rank-$k$ approximation of $A$. This leads to an algorithm to
find such ... more >>>

We consider the problem of finding a $k$-vertex ($k$-edge)
connected spanning subgraph $K$ of a given $n$-vertex graph $G$
while minimizing the maximum degree $d$ in $K$. We give a
polynomial time algorithm for fixed $k$ that achieves an $O(\log
n)$-approximation. The only known previous polynomial algorithms
achieved degree $d+1$ ... more >>>

We study the problem of assigning different communication channels to
acces points in a wireless Local Area Network. Each access point will
be assigned a specific radio frequency channel. Since channels with
similar frequencies interfere, it is desirable to assign far apart
channels (frequencies) to nearby access points. Our goal ... more >>>