Reachability problems in infinite-state systems are often subject to extremely high
complexity. This motivates the investigation of efficient overapproximations, where we add
transitions to obtain a system in which reachability can be decided more efficiently. We
consider bidirected infinite-state systems, where for every transition there is a transition with
opposite effect. We study bidirected reachability in the framework of valence systems, an
abstract model featuring finitely many control states and an infinite-state storage that is …