Cache-oblivious shortest paths in graphs using buffer heap

We present the Buffer Heap (BH), a cache-oblivious priority queue that supports Delete-Min, Delete, and Decrease-Key operations in O( 1 B log2 N B ) amortized block transfers from external memory, where B is the (unknown) block-size and N is the maximum number of elements in the queue. As is common in cache-oblivious algorithms, we assume a ‘tall cache’ (i.e., M = Ω(B1+ ), where M is the size of the main memory). We also assume the Decrease-Key operation only verifies that the element does not exist in the priority queue with a smaller key value, hence it also supports the insert operation in the same amortized bound. The amortized time bound for each operation is O(log N). We also present a Cache-Oblivious Tournament Tree (COTT), which is simpler than the Buffer Heap, but has weaker bounds. Using the Buffer Heap we present cache-oblivious algorithms for undirected and directed single-source shortest path (SSSP) problems for graphs with non-negative edgeweights. On a graph w...

• Type: Conference
• Year: 2004
• Where: SPAA
• Authors: Rezaul Alam Chowdhury, Vijaya Ramachandran
• Keywords: Buffer Heap, Decrease-key Operation, Distributed And Parallel Computing, Priority Queues, SPAA 2004