'From Squeak3.7alpha of 11 September 2003 [latest update: #5707] on 26 February 2004 at 12:07:08 pm'! !SkipList commentStamp: 'KLC 2/26/2004 12:04' prior: 0! From "Skip Lists: A Probabilistic Alternative to Balanced Trees" by William Pugh ( http://epaperpress.com/sortsearch/download/skiplist.pdf ): "Skip lists are a data structure that can be used in place of balanced trees. Skip lists use probabilistic balancing rather than strictly enforcing balancing and as a result the algorithms for insertion and deletion in skip lists are much simpler and significantly faster than equivalent algorithms for balanced trees." Notes: The elements of the skip list must implement #< or you must provide a sort block. ! ]style[(83 55 418)f2,f2Rhttp://epaperpress.com/sortsearch/download/skiplist.pdf;,f2!