21. Tree structures can depict all kinds of mathematical trees of integer sets, et cetera.22. These data structures represent XML documents as a tree structure . 23. Library classification systems group related materials together, typically arranged in a hierarchical tree structure . 24. Thus, the stored data would simply inherit the tree structure of the XML data. 25. The agents are organized in a tree structure called Instance. 26. This often has the circuit geometry of a tree structure . 27. Pointers to data significantly improve performance for repetitive operations such as traversing tree structures . 28. That is, he purposely made a major branch of the OOK's tree structure disappear. 29. There are two primary uses of tree structures in linguistics. 30. The only additional overhead is that of the nested tree structures , one per vertical interval.