;; deleting, and retrieving data from an AVL tree containing n elements
;; is O(log n). It is somewhat more rigidly balanced than other
;; self-balancing binary trees (such as red-black trees and AA trees),
-;; making insertion slighty slower, deletion somewhat slower, and
+;; making insertion slightly slower, deletion somewhat slower, and
;; retrieval somewhat faster (the asymptotic scaling is of course the
;; same for all types). Thus it may be a good choice when the tree will
;; be relatively static, i.e. data will be retrieved more often than