Boug, Gabarrr, Messeguer, Schabanel, Boug, Gabarrr, Messeguer, Schabanel, Boug, Gabarrr, Messeguer, Schabanel, 1998. SPI Height-relaxed AVL rebalancing: A uniied, ne-grained approach to concurrent dictionaries Height-relaxed AVL rebalancing: A uniied, ne-grained approach to concurrent dictionaries.