Comment by lichtenberger

Hm, where else are Lowest Common Ancestors in tree-structures useful? Storing for instance ORDPATH/DeweyIDs allows to simply check for a common prefix (they are hierarchical node labels). I think maybe for locking in a storage system with multiple read/write transactions or to determine which of two given nodes is the firs one in preorder, which is useful for XQuery/XPath processing (to determine the so caslled document order). Can anyone think of other usages? Or for having hierarchical node labels in trees?