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46
Efficient Algorithms for LargeScale Temporal Aggregation
 IEEE TRANS. ON KNOWLEDGE AND DATA ENGINEERING
, 2003
"... The ability to model timevarying natures is essential to many database applications such as data warehousing and mining. However, the temporal aspects provide many unique characteristics and challenges for query processing and optimization. Among the challenges is computing temporal aggregates, whi ..."
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Cited by 13 (2 self)
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The ability to model timevarying natures is essential to many database applications such as data warehousing and mining. However, the temporal aspects provide many unique characteristics and challenges for query processing and optimization. Among the challenges is computing temporal aggregates, which is complicated by having to compute temporal grouping. In this paper, we introduce a variety of temporal aggregation algorithms that overcome major drawbacks of previous work. First, for smallscale aggregations, both the worstcase and averagecase processing time have been improved significantly. Second, for largescale aggregations, the proposed algorithms can deal with a database that is substantially larger than the size of available memory. Third, the parallel algorithm designed on a sharednothing architecture achieves scalable performance by delivering nearly linear scaleup and speedup, even at the presence of data skew. The contributions made in this paper are particularly important because the rate of increase in database size and response time requirements has outpaced advancements in processor and mass storage technology.
DataFlow Frameworks for WorstCase Execution Time Analysis
 RealTime Systems
, 2000
"... The purpose of this paper is to introduce frameworks based on dataflow equations which provide for estimating the worstcase execution time (WCET) of (realtime) programs. These frameworks allow several different WCET analysis techniques, which range from nave approaches to exact analysis, provided ..."
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Cited by 12 (8 self)
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The purpose of this paper is to introduce frameworks based on dataflow equations which provide for estimating the worstcase execution time (WCET) of (realtime) programs. These frameworks allow several different WCET analysis techniques, which range from nave approaches to exact analysis, provided exact knowledge on the program behaviour is available. However, dataflow frameworks can also be used for symbolic analysis based on information derived automatically from the source code of the program. As a byproduct we show that slightly modified elimination methods can be employed for solving WCET dataflow equations, while iteration algorithms cannot be used for this purpose.
Efficient Search in Unbalanced, Randomized PeerToPeer Search Trees
 Ecole Polytechnique Fédérale de Lausanne (EPFL
, 2002
"... Scalable mechanisms to support efficient keybased search in distributed systems are an important part of the infrastructure of peertopeer systems and global information systems. They received substantial attention both in information and communication systems research. A particularly important cl ..."
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Cited by 11 (9 self)
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Scalable mechanisms to support efficient keybased search in distributed systems are an important part of the infrastructure of peertopeer systems and global information systems. They received substantial attention both in information and communication systems research. A particularly important class of approaches is based on a principle of scalable distribution of binary search trees that has been introduced by Plaxton [9]. When adapting the shape of such a tree search structure to the data distribution in order to obtain load balancing, the search trees may become highly unbalanced. We show that for PGrid, a Plaxtonlike distributed search structure that we first introduced in [1], the expected communication cost for searches is strictly limited by where is the number of peers. This result is completely independent of the shape of the underlying tree. The approach exploits the randomization principle of the PGrid structure by virtue of its decentralized and randomized construction process. 1
Simple and efficient algorithm for large scale molecular dynamics simulation in hard disk systems
 Int. J. Mod. Phys. C
, 1999
"... A simple and efficient algorithm of the moleculardynamics simulation of the hard disk system based on the EventDriven method is developed. From the analysis of algorithm, the complexity isO(log N) per 1 event, and the constant coefficient of the complexity is smaller than conventional efficient al ..."
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Cited by 4 (0 self)
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A simple and efficient algorithm of the moleculardynamics simulation of the hard disk system based on the EventDriven method is developed. From the analysis of algorithm, the complexity isO(log N) per 1 event, and the constant coefficient of the complexity is smaller than conventional efficient algorithm based on the concept of CellCrossing Event. The maximum performance of more than 460 millions of collisions per CPUhour on the Alpha600 compatible in a 2500 particle system is achieved. An extension to the infinitespace system based on this algorithm is also proposed. Keywords: EventDriven Molecular Dynamics; Hard Disk System; Algorithm. 1.
A Survey of Algorithms and Data Structures for Range Searching
 ACM Computing Surveys
, 1979
"... ..."
Optimal Independent Spanning Trees on Hypercubes
, 2004
"... Two spanning trees rooted at some vertex r in a graph G are said to be independent if for each vertex v of G, v ≠ r, the paths from r to v in two trees are vertexdisjoint. A set of spanning trees of G is said to be independent if they are pairwise independent. A set of independent spanning trees is ..."
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Cited by 3 (1 self)
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Two spanning trees rooted at some vertex r in a graph G are said to be independent if for each vertex v of G, v ≠ r, the paths from r to v in two trees are vertexdisjoint. A set of spanning trees of G is said to be independent if they are pairwise independent. A set of independent spanning trees is optimal if the average path length of the trees is the minimum. Any kdimensional hypercube has k independent spanning trees rooted at an arbitrary vertex. In this paper, an O(kn) time algorithm is proposed to construct k optimal independent spanning trees on a kdimensional hypercube, where n = 2 k is the number of vertices in a hypercube.
Discrete Pattern Matching Over Sequences And Interval Sets
, 1993
"... Finding matches, both exact and approximate, between a sequence of symbols A and a pattern P has long been an active area of research in algorithm design. Some of the more wellknown byproducts from that research are the diff program and grep family of programs. These problems form a subdomain of a ..."
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Cited by 2 (0 self)
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Finding matches, both exact and approximate, between a sequence of symbols A and a pattern P has long been an active area of research in algorithm design. Some of the more wellknown byproducts from that research are the diff program and grep family of programs. These problems form a subdomain of a larger areas of problems called discrete pattern matching which has been developed recently to characterise the wide range of pattern matching problems. This dissertation presents new algorithms for discrete pattern matching over sequences and develops a new subdomain of problems called discrete pattern matching over interval sets. The problems and algorithms presented here are characterised by pattern matching over interval sets. The problems and al
Priority Queues and Sorting for ReadOnly Data
"... Abstract. We revisit the randomaccessmachine model in which the input is given on a readonly randomaccess media, the output is to be produced to a writeonly sequentialaccess media, and in addition there is a limited randomaccess workspace. The length of the input is N elements, the length of ..."
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Cited by 1 (0 self)
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Abstract. We revisit the randomaccessmachine model in which the input is given on a readonly randomaccess media, the output is to be produced to a writeonly sequentialaccess media, and in addition there is a limited randomaccess workspace. The length of the input is N elements, the length of the output is limited by the computation itself, and the capacity of the workspace is O(S + w) bits,whereS is a parameter specified by the user and w is the number of bits per machine word. We present a stateoftheart priority queue—called an adjustable navigation pile—for this model. Under some reasonable assumptions, our priority queue supports minimum and insert in O(1) worstcase time and extract in O(N/S +lgS) worstcase time, where lg N ≤ S ≤ N / lg N. We also show how to use this data structure to simplify the existing optimal O(N 2 /S + N lg S)time sorting algorithm for this model. 1
Enumerative Aspects of Certain Subclasses of Perfect Graphs
"... We investigate the enumerative aspects of various classes of perfect graphs like cographs, split graphs, trivially perfect graphs and threshold graphs. For subclasses of permutation graphs like cographs and threshold graphs we also determine the number of permutations ß of f1; 2; : : : ; ng such tha ..."
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Cited by 1 (0 self)
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We investigate the enumerative aspects of various classes of perfect graphs like cographs, split graphs, trivially perfect graphs and threshold graphs. For subclasses of permutation graphs like cographs and threshold graphs we also determine the number of permutations ß of f1; 2; : : : ; ng such that the permutation graph G[ß] belongs to that class. We establish an interesting bijection between permutations whose permutation graphs are cographs (P4 free graphs) and permutations that are obtainable using an outputrestricted deque [9] and thereby enumerate such permutations. We also prove that the asymptotic number of permutations of f1; 2; : : : ; ng whose permutation graphs are split graphs is \Theta(4 n = p n). We also introduce a new class of graphs called C5 split graphs, characterize and enumerate them. C5 split graphs form a superclass of split graphs and are not necessarily perfect. All the classes of graphs that we enumerate have a finite family of small forbidden induc...
Optimal algorithms for 2 n AB games – a graphpartition approach
 J. Inf. Sci. Eng
, 2004
"... This paper presents new and systematic methodologies to analyze deductive games and obtain optimal algorithms for 2 × n AB games, where n ≥ 2. We have invented a graphic model to represent the gameguessing process. With this novel approach, we find some symmetric and recursive structures in the pro ..."
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Cited by 1 (1 self)
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This paper presents new and systematic methodologies to analyze deductive games and obtain optimal algorithms for 2 × n AB games, where n ≥ 2. We have invented a graphic model to represent the gameguessing process. With this novel approach, we find some symmetric and recursive structures in the process. This not only reduces the size of the search space, but also helps us to derive the optimum strategies more efficiently. By using this technique, we develop optimal strategies for 2 × n AB games in the expected and worst cases, and are able to derive the following new results: (1) ⎡n/2 ⎤ + 1 guesses are necessary and sufficient for 2 × n AB games in the worst case, (2) the minimum number of guesses required for 2 × n AB games in the expected case is (4n 3 + 21n 2 76n + 72)/12n(n 1) if n is even, and (4n 3 + 21n 2 82n + 105)/12n(n 1) if n is odd. The optimization of this problem bears resemblance with other computational problems, such as circuit testing, differential cryptanalysis, online models with equivalent queries, and additive search problems. Any conclusion of this kind of deductive game may be applied, although probably not directly, to any of these problems, as well as to any other combinatorial optimization problem.