sentences:  More formally, consider a subtree "T", rooted at "p", with children "l" (left) and "r" (right).We set "r" as the preferred child of "p" if the most recently accessed node in "T" is in the subtree rooted at "r", and "l" as the preferred child otherwise.Note that if the most recently accessed node of "T" is "p" itself, then "l" is the preferred child by definition.