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23
Searching in Constant Time and Minimum Space
, 1995
"... This report deals with techniques for minimal space representation of a subset of elements from a bounded universe so that various types of searches can be performed in constant time. In particular, we introduce a data structure to represent a subset of N elements of [0�:::�M;1] in a number of bits ..."
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Cited by 11 (8 self)
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This report deals with techniques for minimal space representation of a subset of elements from a bounded universe so that various types of searches can be performed in constant time. In particular, we introduce a data structure to represent a subset of N elements of [0�:::�M;1] in a number of bits close to the informationtheoretic minimum and use the structure to answer membership queries in constant time. Next, we describe a representation of an arbitrary subset of points on an M M grid such that closest neighbour queries (under L1 and L1) can be performed in constant time. This structure requires M 2 + o(M 2) bits. Finally, under a byte overlap model of memory we present an M + o(M) bit, constant time solution to the dynamic onedimensional closest neighbour problem (hence, also unionsplitfind and priority queue problems) on [0�:::�M; 1].
Parallel Maximum Sum Algorithms on Interconnection Networks
 Queen’s Uni. Dept. of Com. and
, 1999
"... We develop parallel algorithms for both onedimensional and twodimensional versions of the maximum sum problem (or max sum for short) on several interconnection networks. These algorithms are all based on a simple scheme that uses prefix sums. To this end, we first show how to compute prefix sums o ..."
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Cited by 10 (0 self)
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We develop parallel algorithms for both onedimensional and twodimensional versions of the maximum sum problem (or max sum for short) on several interconnection networks. These algorithms are all based on a simple scheme that uses prefix sums. To this end, we first show how to compute prefix sums of N elements on a hypercube, a star, and a pancake interconnection network of size p (where p N) in optimal time of O( N p + log p). For the problem of maximum subsequence sum, the 1D version of the max sum problem, we find an algorithm that computes the maximum sum of N elements on the aforementioned networks of size p, all with a running time of O( N p + log p), which is optimal in view of the trivial\Omega\Gamma N p + log p) lower bound. When p = O( N log N ), our algorithm computes the max sum in O(log N) time, resulting in an optimal cost of O(N ). This result also matches the performance of two previous algorithms that are designed to run on PRAM. Our 1D max sum algorithm can...
An Exception Handling Framework for NVersion Programming in Object Oriented Systems
 in ISORC ‘00, ObjectOriented RealTime Distributed Computing, 2000 Proceedings. Third IEEE International Symposium, March 2000 Pages:226 – 233
, 2000
"... This paper proposes an approach for introducing exception handling into object oriented Nversion programming (NVP). We start with outlining general principles of structuring systems with diversity and show why it is important to use exceptions while developing and using diverselydeveloped softwar ..."
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Cited by 9 (3 self)
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This paper proposes an approach for introducing exception handling into object oriented Nversion programming (NVP). We start with outlining general principles of structuring systems with diversity and show why it is important to use exceptions while developing and using diverselydeveloped software. Internal version exceptions and external exceptions, which the diverselydesigned class can propagate, are clearly separated in our framework: each version has its own internal exceptions but the external exceptions of all versions have to be the same and identical to the interface exceptions of the whole class. This scheme requires an adjudicator of a special kind to allow interface exception signalling when a majority of versions have signalled the same exception. We demonstrate these ideas using a general framework for introducing NVP into objectoriented systems which we have developed recently [1]. This framework follows all principles of structured NVP: software diversity is introduced here at the level of classes and encapsulated into the diverselydesigned class. We discuss the internal structure of this class and the interfaces of its subcomponents; and show how the NVP controller works, version execution is coordinated and reuse operates here. This framework makes use of many advantages objectoriented programming has. For the demonstration, it has been implemented in Ada. The paper finishes with a comparison of our proposal with some existing NVP schemes and with a discussion of our future work. 1. Introduction
Speeding up Relief algorithms with kd trees
, 1998
"... There are certain problems in machine learning which desire special attention when we scale up the size of the data or move towards data mining. One of them is the problem of searching nearest neighbours of a given point in k dimensional space. If the space is ! k than kd trees can solve the prob ..."
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Cited by 5 (0 self)
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There are certain problems in machine learning which desire special attention when we scale up the size of the data or move towards data mining. One of them is the problem of searching nearest neighbours of a given point in k dimensional space. If the space is ! k than kd trees can solve the problem in asymptotically optimal time under certain conditions. We investigate the use of kd trees in nearest neighbour search in the family of attribute estimation algorithms Relief on typical machine learning databases and examine their performance under various conditions.
The Cleave And Fill Tool: An AllHexahedral Refinement Algorithm For Swept Meshes
, 2000
"... Sweeping algorithms provide the ability to generate all hexahedral meshes on a wide variety of threedimensional bodies. The work presented here provides a method to refine these meshes by first defining a path through either the source or the target mesh and next by locating the sweeping layer to ..."
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Cited by 4 (2 self)
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Sweeping algorithms provide the ability to generate all hexahedral meshes on a wide variety of threedimensional bodies. The work presented here provides a method to refine these meshes by first defining a path through either the source or the target mesh and next by locating the sweeping layer to initiate the refinement. A major contribution of this work is the ability to automatically find a minimal distance path through the target or source mesh. The refinement is accomplished by using the pillowing procedure as proposed by Mitchell. [1] Keywords: mesh generation, hexahedral meshing, refinement, sweeping, 2 D 3 samitch@sandia.gov 4 drwhite@sandia.gov 5 rjmeyer@sandia.gov Scott Mitchell, David White, and Ray Meyers work at Sandia National Laboratories, a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DEAC0494AL8500. 1. INTRODUCTION Threedimensional finite element analysis ...
Computing Graph Invariants on Rotagraphs Using Dynamic Algorithm Approach: The Case of (2,1)Colorings and Independence Numbers
, 2001
"... Rotagraphs generalize all standard products of graphs in which one factor is a cycle. A computer based approach for searching graph invariants on rotagraphs is proposed and two of its applications are presented. First, the numbers of the Cartesian product of a cycle and a path are computed, where t ..."
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Cited by 3 (1 self)
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Rotagraphs generalize all standard products of graphs in which one factor is a cycle. A computer based approach for searching graph invariants on rotagraphs is proposed and two of its applications are presented. First, the numbers of the Cartesian product of a cycle and a path are computed, where the number of a graph G is the minimum number of colors needed in a (2,1)coloring of G. The independence numbers of the family of the strong product graphs C 7 2 \Theta C 7 2 \Theta C 2k+1 are also obtained. Key words: rotagraph, dynamic algorithm, (2,1)coloring, independence number, Cartesian product of graphs, strong product of graphs AMS subject classification: 05C85, 05C15, 05C69, 68R10 Proposed running head: (2,1)colorings and independence numbers of rotagraphs Supported by the Ministry of Education, Science and Sport of Slovenia under the grant 0101504. 1 1
Object Extraction from Terrestrial Laser Scanning Data
, 2009
"... Terrestrial laser scanning emerges as a leading technology for direct 3D documentation of natural scenes irrespective of their complexity. The detailed level of description comes however at the cost of huge volume of data in form of unorganized, unevenly spaced, threedimensional points. The cloud o ..."
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Cited by 2 (0 self)
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Terrestrial laser scanning emerges as a leading technology for direct 3D documentation of natural scenes irrespective of their complexity. The detailed level of description comes however at the cost of huge volume of data in form of unorganized, unevenly spaced, threedimensional points. The cloud of points provides a geometric description of the scanned scene but carries no semantic information regarding the objects within. Consequently, direct extraction of objects turns a challenging task. So far, research has focused on the extraction of welldefined objects with clear geometric characterization (e.g., plane, cylinders). Objects were extracted using segmentation algorithms which led to heavy computational efforts and were sensitive to scanning resolution and to artifacts. Effective working schemes for the extraction of objects require efficient and more general pointcloud processing methodologies. Such schemes are instrumental if aiming towards turning laser scanners into actual 3D mapping tools, and not only as means for characterization of surface geometry. We present in this paper a model for the extraction of objects in natural and cluttered scenes. The proposed approach is predominantly based on using a panoramic representation of the individual laser scans. We discuss the advantages of this representation for a direct scene
On The ShuffleExchange Permutation Network
 IN PROCEEDINGS OF THE 3 RD INTERNATIONAL SYMPOSIUM ON PARALLEL ARCHITECTURES, ALGORITHMS AND NETWORKS (ISPAN '97), LOS ALAMITOS
, 1997
"... The shuffleexchange permutation network (SEP n ) is a fixed degree Cayley graph which has been proposed as a basis for massively parallel systems. We propose a routing algorithm with an upper bound of (5/8)n 2 + O(n), where n is the length of the permutation. (This improves on a (9/8)n 2 routin ..."
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Cited by 1 (1 self)
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The shuffleexchange permutation network (SEP n ) is a fixed degree Cayley graph which has been proposed as a basis for massively parallel systems. We propose a routing algorithm with an upper bound of (5/8)n 2 + O(n), where n is the length of the permutation. (This improves on a (9/8)n 2 routing algorithm described earlier [5].) Thus, the diameter of SEP n is at most (5/8) n 2 + O(n). We also show that the diameter is at least n 2 / 2  O(n). We demonstrate that SEP n has a Hamilton cycle, for n t 3, left open in [5], and describe embeddings of variabledegree Cayley networks, such as bubblesort networks [1], star networks [2] and pancake networks [4] into SEP n . Our embeddings for these networks are substantial improvements of earlier results stated in [5].
unknown title
, 2001
"... www.elsevier.com/locate/sigpro Rate–distortion optimization ofthe image compression algorithm based on the warped discrete cosine transform ..."
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www.elsevier.com/locate/sigpro Rate–distortion optimization ofthe image compression algorithm based on the warped discrete cosine transform