Editing Disjoint-set data structure (section)

===Better worst-case time per operation===
The worst-case time of the <code>Find</code> operation in trees with '''Union by rank''' or '''Union by weight''' is <math>\Theta(\log n)</math> (i.e., it is <math>O(\log n)</math> and this bound is tight). 
In 1985, N. Blum gave an implementation of the operations that does not use path compression, but compresses trees during <math>union</math>. His implementation runs in <math>O(\log n / \log\log n)</math> time per operation,<ref>{{cite journal |last1=Blum |first1=Norbert |title=On the Single-Operation Worst-Case Time Complexity of the Disjoint Set Union Problem |journal=2nd Symp. On Theoretical Aspects of Computer Science |date=1985 |pages=32–38}}</ref> and thus in comparison with Galler and Fischer's structure it has a better worst-case time per operation, but inferior amortized time. In 1999, Alstrup et al. gave a structure that has optimal worst-case
time <math>O(\log n / \log\log n)</math> together with inverse-Ackermann amortized time.<ref>{{cite book |last1=Alstrup |first1=Stephen |last2=Ben-Amram |first2=Amir M. |last3=Rauhe |first3=Theis  |title=Proceedings of the thirty-first annual ACM symposium on Theory of Computing |chapter=Worst-case and amortised optimality in union-find (Extended abstract) |date=1999 |pages=499–506 |doi=10.1145/301250.301383|isbn=1581130678 |s2cid=100111 }}</ref>