Since AVL trees were invented in 1962, two major open questions about rebalancing operations, which found positive answers in other balanced binary search trees, were left open: can these operations be performed top-down (with a fixed look-ahead), and can they use an amortised constant number of write operations per update? We propose an algorithm that solves both questions positively.
@InProceedings{juge:LIPIcs.ESA.2025.49, author = {Jug\'{e}, Vincent}, title = {{Efficient Top-Down Updates in AVL Trees}}, booktitle = {33rd Annual European Symposium on Algorithms (ESA 2025)}, pages = {49:1--49:15}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-395-9}, ISSN = {1868-8969}, year = {2025}, volume = {351}, editor = {Benoit, Anne and Kaplan, Haim and Wild, Sebastian and Herman, Grzegorz}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ESA.2025.49}, URN = {urn:nbn:de:0030-drops-245172}, doi = {10.4230/LIPIcs.ESA.2025.49}, annote = {Keywords: AVL trees, data structures, amortised complexity} }
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