source: [lemma=path] [word=□] □
destination: [lemma=path] [word=uses] □
spec: Personnel assigned to the Main Operating Base will be required to travel on an as needed basis to any and all sites operated and / or supported by AD . While related work on paths uses multiple trees [ YOUNG ] , there is no need to keep track of multiple trees when a root node may have a variable number of children , and thus can hold together all of the path trees .