The input to the {\em Graph Clustering Problem}\/
consists of a sequence of integers $m_1,...,m_t$
and a sequence of $\sum_{i=1}^{t}m_i$ graphs.
The question is whether the equivalence classes,
under the graph isomorphism relation,
of the input graphs have sizes which match the input sequence of integers.
In this note we ... more >>>

A visual cryptography scheme for a
set $\cal P $ of $n$ participants is a method to encode a secret
image $SI$ into $n$ shadow images called shares, where each participant in
$\cal P$ receives one share. Certain qualified subsets of participants
can ``visually'' recover the secret image, but
other, ... more >>>