SODA Conference 2013 Conference Paper
Multiway Simple Cycle Separators and I/O-Efficient Algorithms for Planar Graphs
- Freek van Walderveen
- Norbert Zeh
- Lars Arge
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SODA Conference 2013 Conference Paper
FOCS Conference 2009 Conference Paper
In orthogonal range reporting we are to preprocess N points in d-dimensional space so that the points inside a d-dimensional axis-aligned query box can be reported efficiently. This is a fundamental problem in various fields, including spatial databases and computational geometry. In this paper we provide a number of improvements for three and higher dimensional orthogonal range reporting: In the pointer machine model, we improve all the best previous results, some of which have not seen any improvements in almost two decades. In the I/O-model, we improve the previously known three-dimensional structures and provide the first (non-trivial) structures for four and higher dimensions.
FOCS Conference 2006 Conference Paper
We develop the first linear-space data structures for dynamic planar point location in general subdivisions that achieve logarithmic query time and poly-logarithmic update time
SODA Conference 2005 Conference Paper
FOCS Conference 2003 Conference Paper
We present the first I/O-efficient algorithms for the following fundamental problems on directed planar graphs: finding the strongly connected components, finding a simple-path 2/3-separator, and computing a depth-first spanning (DFS) tree. Our algorithms for the first two problems perform O(sort(N)) I/Os, where N = V + E and sort(N) = /spl Theta/((N/B)) is the number of I/Os required to sort N elements. The DFS-algorithm performs O(sort(N) log(N/M)) I/Os, where M is the number of elements that fit into main memory.
STOC Conference 2002 Conference Paper
(MATH) In this paper we develop an optimal cache-oblivious priority queue data structure, supporting insertion, deletion, and deletemin operations in O ( 1 \over B log M/B N \over B ) amortized memory transfers, where M and B are the memory and block transfer sizes of any two consecutive levels of a multilevel memory hierarchy. In a cache-oblivious data structure, M and B are not used in the description of the structure. The bounds match the bounds of several previously developed external-memory (cache-aware) priority queue data structures, which all rely crucially on knowledge about M and B . Priority queues are a critical component in many of the best known external- memory graph algorithms, and using our cache-oblivious priority queue we develop several cache- oblivious graph algorithms.
SODA Conference 1999 Conference Paper
SODA Conference 1998 Conference Paper
SODA Conference 1998 Conference Paper
STOC Conference 1997 Conference Paper
FOCS Conference 1996 Conference Paper
The authors present a space- and I/O-optimal external-memory data structure for answering stabbing queries on a set of dynamically maintained intervals. The data structure settles an open problem in databases and I/O algorithms by providing the first optimal external-memory solution to the dynamic interval management problem, which is a special case of 2-dimensional range searching and a central problem for object-oriented and temporal databases and for constraint logic programming. The data structure simultaneously uses optimal linear space (that is, O(N/B) blocks of disk space) and achieves the optimal O(log/sub B/ N+T/B) I/O query bound and O(log/sub B/ N) I/O update bound, where B is the I/O block size and T the number of elements in the answer to a query. The structure is also the first optimal external data structure for a 2-dimensional range searching problem that has worst-case as opposed to amortized update bounds. Part of the data structure uses a novel balancing technique for efficient worst-case manipulation of balanced trees, which is of independent interest.