Many program analyses need to reason about pairs of matching actions, such as call/return, lock/unlock, or set-field/get-field. The family Dyck languages { D k }, where has kinds parenthesis pairs, can be used model actions balanced parentheses. Consequently, many program-analysis problems formulated Dyck-reachability on edge-labeled digraphs. Interleaved (InterDyck-reachability), denoted by ⊙ ...