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Experimental study of high performance priority queues, 2007. Undergraduate Honors Thesis
, 2007
"... The priority queue is a very important and widely used data structure in computer science, with a variety of applications including Dijkstra’s Single Source Shortest Path algorithm on sparse graph types. This study presents the experimental results of a variety of priority queues. The focus of the e ..."
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The priority queue is a very important and widely used data structure in computer science, with a variety of applications including Dijkstra’s Single Source Shortest Path algorithm on sparse graph types. This study presents the experimental results of a variety of priority queues. The focus of the experiments is to measure the speed and performance of highly specialized priority queues in outofcore and memory intensive situations. The priority queues are run incore on small input sizes as well as outofcore using large input sizes and restricted memory. The experiments compare a variety of wellknown priority queue implementations such as Binary Heap with highly specialized implementations, such as 4ary Aligned Heap, Chowdhury and Ramachandran’s Auxiliary Buffer Heap, and Fast Binary Heap. The experiments include CacheAware as well as CacheOblivious priority queues. The results indicate that the highperformance priority queues easily outperform traditional implementations. Also, overall the Auxiliary Buffer Heap has the best performance among the priority queues considered in most incore and outofcore situations. 1 1
Queaps
, 2002
"... We present a new priority queue data structure, the queap, that executes insertion in O(1) amortized time and extractmin in O(log(k + 2)) amortized time if there are k items that have been in the heap longer than the item to be extracted. Thus if the operations on the queap are rstin rstout ..."
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We present a new priority queue data structure, the queap, that executes insertion in O(1) amortized time and extractmin in O(log(k + 2)) amortized time if there are k items that have been in the heap longer than the item to be extracted. Thus if the operations on the queap are rstin rstout, as on a queue, each operation will execute in constant time. This idea of trying to make operations on the least recently accessed items fast, which we call the queueish property, is a natural complement to the working set property of certain data structures, such as splay trees and pairing heaps, where operations on the most recently accessed data execute quickly. However, we show that the queueish property is in some sense more dicult than the working set property by demonstrating that it is impossible to create a queueish binary search tree, but that many search data structures can be made almost queueish with a O(log log n) amortized extra cost per operation.
Nearentropy hotlink assignments
 In Proceedings of the 14th Annual European Symposium on Algorithms (ESA
, 2006
"... Abstract. Consider a rooted tree T of arbitrary maximum degree d representing a collection of n web pages connected via a set of links, all reachable from a source home page represented by the root of T. Each web page i carries a weight wi representative of the frequency with which it is visited. By ..."
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Abstract. Consider a rooted tree T of arbitrary maximum degree d representing a collection of n web pages connected via a set of links, all reachable from a source home page represented by the root of T. Each web page i carries a weight wi representative of the frequency with which it is visited. By adding hotlinks — shortcuts from a node to one of its descendents — we wish to minimize the expected number of steps l needed to visit pages from the home page, expressed as a function of the entropy H(p) of the access probabilities p. This paper introduces several new strategies for effectively assigning hotlinks in a tree. For assigning exactly one hotlink per node, our method guarantees an upper bound on l of 1.141H(p)+1 if d> 2 and 1.08H(p)+2/3 if d = 2. We also present the first efficient general methods for assigning at most k hotlinks per node in trees of arbitrary maximum degree, achieving bounds on l of at most
Design and Analysis of Algorithms: Course Notes
"... Contents 1 Overview of Course 3 1.1 Amortized Analysis : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 3 2 Splay Trees 5 2.1 Use of Splay Operations : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 5 2.2 Time for a Splay Operation ..."
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Contents 1 Overview of Course 3 1.1 Amortized Analysis : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 3 2 Splay Trees 5 2.1 Use of Splay Operations : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 5 2.2 Time for a Splay Operation : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 6 3 Amortized Time for Splay Trees 8 3.1 Additional notes : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 11 4 Maintaining Disjoint Set's 12 4.1 Disjoint set operations: : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 12 4.2 Data structure: : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 12 4.3 Union by rank : : : : : : : : : : : : : : : : :
KIST: A new encryption algorithm based on splay
"... In this paper, we proposed a new encryption algorithm called KIST. This algorithm uses an asynchronous key sequence and a splay tree. It is very efficient in the usage of both space and time. Some elementary security tests have been done. Key words asynchronous key sequence, splay tree, symmetric ke ..."
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In this paper, we proposed a new encryption algorithm called KIST. This algorithm uses an asynchronous key sequence and a splay tree. It is very efficient in the usage of both space and time. Some elementary security tests have been done. Key words asynchronous key sequence, splay tree, symmetric key encryption 1
APPLICATIOIU OF SPLAY TREES TO DATA COMPRESSION
"... The splayprefix algorithm is one of the simplest and fastest adaptive data compression algorithms based on the use of a prefix code. The data structures used in the splayprefix algorithm can also be applied to arithmetic data compression. Applications of these algorithms to encryption and image pr ..."
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The splayprefix algorithm is one of the simplest and fastest adaptive data compression algorithms based on the use of a prefix code. The data structures used in the splayprefix algorithm can also be applied to arithmetic data compression. Applications of these algorithms to encryption and image processing are suggested.
Rotation Distance, Triangulations of Planar Surfaces and Hyperbolic Geometry (Extended Abstract)
 PROC. ISAAC'94 (5TH INTERNATIONAL SYMPOSIUM ON SYMBOLIC AND ALGEBRAIC COMPUTATION
, 1994
"... In a beautiful paper, Sleator, Tarjan and Thurston solved the problem of maximum rotation distance of two binary trees. Equivalently they solved the problem of rotation distance of triangulations on the disk. We extend their results to rotation distance of triangulations of other planar surfaces ..."
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In a beautiful paper, Sleator, Tarjan and Thurston solved the problem of maximum rotation distance of two binary trees. Equivalently they solved the problem of rotation distance of triangulations on the disk. We extend their results to rotation distance of triangulations of other planar surfaces. We give upper and lower bounds for this problem. Equivalently, by duality, one can interpret our results as bounds for rotation distance of the dual graphs of the triangulation graphs. They are the counter parts to binary trees in the case of disk. In the case of the annulus, by cutting along an edge between the inner and outer boundary circles, we obtain rooted binary trees with a distinguished path to a leaf. The upper bound is obtained by looking at the triangulations in the universal covering space, and the lower bound is obtained by extending and applying the technique of volume estimate in hyperbolic geometry.
Srikanth Ramamurthy. ALockFree Approach to Object Sharing in RealTime Systems
, 1997
"... This work aims to establish the viabilityoflockfree object sharing in uniprocessor realtime systems. Naive usage of conventional lockbased objectsharing schemes in realtime systems leads to unbounded priority inversion. A priority inversion occurs when a task is blocked by a lowerpriority task ..."
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This work aims to establish the viabilityoflockfree object sharing in uniprocessor realtime systems. Naive usage of conventional lockbased objectsharing schemes in realtime systems leads to unbounded priority inversion. A priority inversion occurs when a task is blocked by a lowerpriority task that is inside a critical section. Mechanisms that bound priority inversion usually entail kernel overhead that is sometimes excessive. We propose that lockfree objects o er an attractive alternative to lockbased schemes because they eliminate priority inversion and its associated problems. On the surface, lockfree objects may seem to be unsuitable for hard realtime systems because accesses to such objects are not guaranteed to complete in bounded time. Nonetheless, we present scheduling conditions that demonstrate the applicability of lockfree objects in hard realtime systems. Our scheduling conditions are applicable to schemes such as
Algorithms for the Character Theory of the Symmetric Group
"... The representation theory of the symmetric groups Su aside from being extremely elegant and interesting in its own right can be used in a number of ways to obtain information about the representation theory of other classes of groups. This theory also turns out to have applications in such diverse ..."
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The representation theory of the symmetric groups Su aside from being extremely elegant and interesting in its own right can be used in a number of ways to obtain information about the representation theory of other classes of groups. This theory also turns out to have applications in such diverse areas of interest as atomic physics and quantum chemistry
Open Data Structures (in Java)
"... I am grateful to Nima Hoda, who spent a summer tirelessly proofreading many of the chapters in this book, and to the students in the Fall 2011 offering of COMP2402/2002, who put up with the first draft of this book and spotted many typographic, grammatical, and factual errors in the first draft. i W ..."
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I am grateful to Nima Hoda, who spent a summer tirelessly proofreading many of the chapters in this book, and to the students in the Fall 2011 offering of COMP2402/2002, who put up with the first draft of this book and spotted many typographic, grammatical, and factual errors in the first draft. i Why This Book? There are plenty of books that teach introductory data structures. Some of them are very good. Most of them cost money, and the vast majority of computer science undergraduate students will shellout at least some cash on a data structures book. Thereareafewfreedatastructuresbooksavailableonline. Someareverygood,but most of them are getting old. The majority of these books became free when the author and/or publisher decided to stop updating them. Updating these books is usually not