In this paper, we are concerned with randomized OBDDs and randomized
read-k-times branching programs. We present an example of a Boolean
function which has polynomial size randomized OBDDs with small,
one-sided error, but only non-deterministic read-once branching
programs of exponential size. Furthermore, we discuss a lower bound
technique for randomized ... more >>>

We obtain an exponential separation between consecutive
levels in the hierarchy of classes of functions computable by
polynomial-size syntactic read-$k$-times branching programs, for
{\em all\/} $k>0$, as conjectured by various
authors~\cite{weg87,ss93,pon95b}. For every $k$, we exhibit two
explicit functions that can be computed by linear-sized
read-$(\kpluso)$-times branching programs but ... more >>>

We extend the tools for proving lower bounds for randomized branching
programs by presenting a new technique for the read-once case which is
applicable to a large class of functions. This technique fills the gap
between simple methods only applicable for OBDDs and the well-known
"rectangle technique" of Borodin, Razborov ... more >>>

It is well known that every finite Abelian group $G$ can be
represented as a product of cyclic groups: $G=G_1\times
G_2\times\cdots G_t$, where each $G_i$ is a cyclic group of size
$p^j$ for some prime $p$ and integer $j\ge 1$. If $a_i$ is the
generator of the cyclic group of ... more >>>

We show that the promise problem of distinguishing $n$-bit strings of hamming weight $\ge 1/2 + \Omega(1/\log^{d-1} n)$ from strings of weight $\le 1/2 - \Omega(1/\log^{d-1} n)$ can be solved by explicit, randomized (unbounded-fan-in) poly(n)-size depth-$d$ circuits with error $\le 1/3$, but cannot be solved by deterministic poly(n)-size depth-$(d+1)$ circuits, ... more >>>