Priority Queues Resilient to Memory Faults

摘要

In the faulty-memory RAM model, the content of memory cells can get corrupted at any time during the execution of an algorithm, and a constant number of uncorruptible registers are available. A resilient data structure in this model works correctly on the set of uncorrupted values. In this paper we introduce a resilient priority queue. The deletemin operation of a resilient priority queue returns either the minimum uncorrupted element or some corrupted element. Our resilient priority queue uses O(n) space to store n elements. Both insert and deletemin operations are performed in O(log n + δ) time amortized, where δ is the maximum amount of corruptions tolerated. Our priority queue matches the performance of classical optimal priority queues in the RAM model when the number of corruptions tolerated is O(logn). We prove matching worst case lower bounds for resilient priority queues storing only structural information in the uncorruptible registers between operations.