  We consider a model of two interdependent networks, where every node in one
network depends on one or more supply nodes in the other network and a node
fails if it loses all of its supply nodes. We develop algorithms to compute the
failure probability of a path, and obtain the most reliable path between a pair
of nodes in a network, under the condition that each supply node fails
independently with a given probability. Our work generalizes the classical
shared risk group model, by considering multiple risks associated with a node
and letting a node fail if all the risks occur. Moreover, we study the diverse
routing problem by considering two paths between a pair of nodes. We define two
paths to be $d$-failure resilient if at least one path survives after removing
$d$ or fewer supply nodes, which generalizes the concept of disjoint paths in a
single network, and risk-disjoint paths in a classical shared risk group model.
We compute the probability that both paths fail, and develop algorithms to
compute the most reliable pair of paths.
