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Theory Seminar

Theory Seminar: Thomas Dueholm (CTIC, Aarhus University)

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Wednesday 11 March 2015,  at 14:15 - 15:00


Building 5335, Nygaard-327

Hollow Heaps

We introduce the hollow heap, a very simple data structure with the same amortized efficiency as the classical Fibonacci heap. All heap operations, except delete and delete-min, take O(1) time, worst case as well as amortized; delete and delete-min take O(log n) amortized time. Hollow heaps are by far the simplest structure to achieve this. Hollow heaps combine two novel ideas: the use of lazy deletion and re-insertion to do decrease-key operations, and the use of a dag (directed acyclic graph) instead of a tree or set of trees to represent a heap. Lazy deletion produces hollow nodes (nodes without items), giving the data structure its name.

Joint work with Haim Kaplan, Robert E. Tarjan, and Uri Zwick.