  We explore a generalization of set reconciliation, where the goal is to
reconcile sets of sets. Alice and Bob each have a parent set consisting of $s$
child sets, each containing at most $h$ elements from a universe of size $u$.
They want to reconcile their sets of sets in a scenario where the total number
of differences between all of their child sets (under the minimum difference
matching between their child sets) is $d$. We give several algorithms for this
problem, and discuss applications to reconciliation problems on graphs,
databases, and collections of documents. We specifically focus on graph
reconciliation, providing protocols based on set of sets reconciliation for
random graphs from $G(n,p)$ and for forests of rooted trees.
