Editing Binary search tree (section)

=== Weight-balanced trees ===
{{main|Weight-balanced tree}}
In a weight-balanced tree, the criterion of a balanced tree is the number of leaves of the subtrees. The weights of the left and right subtrees differ at most by <math>1</math>.<ref>{{Cite journal|doi=10.1016/0304-3975(80)90018-3|title=On the Average Number of Rebalancing Operations in Weight-Balanced Trees|journal=Theoretical Computer Science|volume=11|issue=3|pages=303–320|year=1978|last1=Blum|first1=Norbert|last2=Mehlhorn|first2=Kurt|url=http://scidok.sulb.uni-saarland.de/volltexte/2011/4019/pdf/fb14_1978_06.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://scidok.sulb.uni-saarland.de/volltexte/2011/4019/pdf/fb14_1978_06.pdf |archive-date=2022-10-09 |url-status=live}}</ref>{{r|peter11|pp=61}} However, the difference is bound by a ratio <math>\alpha</math> of the weights, since a strong balance condition of <math>1</math> cannot be maintained with <math>O(\log n)</math> rebalancing work during insert and delete operations. The <math>\alpha</math>-weight-balanced trees gives an entire family of balance conditions, where each left and right subtrees have each at least a fraction of <math>\alpha</math> of the total weight of the subtree.{{r|peter11|pp=62}}