Apr 24, 2010 the database community has devoted extensive amount of efforts to indexing and querying temporal data in the past decades. Distributed topk monitoring stanford infolab stanford university. Whenk 1, it is known asa minimum costgroupsteinertree problem which is npcomplete. The currently best algorithms in practical applications for computing the closeness for all nodes exactly in unweighted graphs are based on breadthfirst search bfs from every node. To the best of our knowledge, this is the first paper proposing parallel algorithms to process topk. Halldorsson, atsuhiro takasu, keisuke tanaka pages 1022. Anytime measures for topk algorithms semantic scholar. The goal is to ensure ps victory by shifting p higher. This was formulated to minimize the number of questions under the constraint of the number of rounds. In recent years, crowdsourcing has emerged as a new computing paradigm for bridging the gap between human and machinebased computation. Some generic indexing structures based on rtrees do support.
Evolved parameterized selection for evolutionary algorithms, samuel nathan richter. New methods in parameterized algorithms and complexity ucsb. The linq library currently does not have a dedicated top k implementation. The treewidth of a graph is one of the most frequently used tools in parameterized algorithms.
In section 6, we explore the connection between prf. We observe that the number of keywords, l,is small, and propose a novel parameterized solution, with l. Computer science masters theses computer science theses and. However, insufficient amount of attention has been paid to temporal ranking queries. Our key algorithm is an onlogn algorithm for ranking using a prfe function over lowcorrelation datasets. Computing top k closeness centrality faster in unweighted. A parameterized perspective on protecting elections. In this paper, we studied the problem of answering top k queries with crowds.
Pdf efficient parameterized algorithms for biopolymer. Top k queries join queries product combinations combination ranking abstract given a relation that contains main products and a set of relations corresponding to accessory products that can be combined with a main product, the exploratory top k join query retrieves the k best combinations of main and accessory products based on user preferences. Our algorithm is a parameterized algorithm 11, in which the naturally small parameter k determined by a statistical cutoff re. The new algorithm with the time complexity oktn2 is more ef. Processing topk queries using the nave algorithm is very expensive for. Before joining ucf, i have worked as a research scientistpostdoc in the school of computational science and engineering, georgia institute o f technology, atlanta with prof. Intuitively, knnoptimal performs a range search with a variable shrinking. Goodrich department of computer science university of california, irvine. Contents preface xiii i foundations introduction 3 1 the role of algorithms in computing 5 1.
Siam journal on discrete mathematics society for industrial. This book constitutes the refereed proceedings of the 21st annual european symposium on algorithms, esa 20, held in sophia antipolis, france, in september 20 in the context of the combined confere. Parameterized complexity of committee elections with. Below, we outline this process for the algorithms given in 7 for prf. In particular, we present a linear time algorithm for the top k problem which has a competitive ratio of equation. Data structures and algorithms in java 6th edition pdf free. Prices matter for the parameterized complexity of shift. In particular, we show that for a large class of wellknown np optimization problems, there are parameterized topk algorithms that produce the best k solutions for the problems in feasible amount. Parameterized algorithms for conflictfree colorings of graphs. Programs usually use the orderby function followed by the take function. Our approach to parameterized top k algorithms proceeds in two stages. On the complexity of the star phub center problem with parameterized triangle inequality. Comparing top k lists siam journal on discrete mathematics.
We study the recently introduced connected feedback vertex set cfvs problem from the viewpoint of parameterized algorithms. Data structures and algorithms in java sixth edition michael t. This book constitutes the refereed proceedings of the 21st annual european symposium on algorithms, esa 20, held in sophia antipolis, france, in september 20 in the context of the combined conference algo 20. This comprehensive textbook presents a clean and coherent account of most fundamental tools and techniques in parameterized algorithms and is a selfcontained guide to the area.
Optimal algorithms for selecting topk combinations of. Reduction to a problem kernel then means to replace instance i,k by a. In section 4, we present our generating functionsbased algorithms for ranking. A general framework of our parameterized topk algorithms can be divided into two components. Thus, even for sparse graphs, these algorithms require quadratic running time in the worst case, which is prohibitive for large networks. In this paper we initiate a study of anytime topk algorithms. If thats correct, then start with the first 10 items in each list will allow you to generate the correct output if you only want unique items in the output, but the inputs might contain duplicates, then you need 10 unique items in each list. To address this problem, we modeled a parameterized framework with two parameters b and r. Siam journal on computing society for industrial and. Multiquery optimization for continuous topk query workloads by avani shastri a thesis submitted to the faculty of the worcester polytechnic institute in partial ful. In this paper, we propose two new algorithms for processing topk queries over sorted lists. Cfvs is the connected variant of the classical feedback vertex set problem and is defined as follows. If i understand your question correctly, the correct output is the top 10 items, irrespective of the list from which each came.
Html and pdf documents obtained from a crawl of the. In contrast, our algorithm solves the generalized topk. Intuitively, the policy gradient objective either increases the probability of the action when the return is higher than expected a t0 or decreases the probability when the return is lower than expected a t algorithms in the literature, such as lenstras algorithm for integer linear programming 319 or the disjoint paths algorithm of robertson and seymour 402, it was only in the late 1980s that downey and ellofws 149, building on joint work with langston 180, 182, 183, proposed the systematic exploration of parameterized algorithms. Besides the applications to the task of identifying good notions of dissimilarity between two top k lists, our results imply polynomialtime constantfactor approximation algorithms for the rank aggregation problem with respect to a large class of distance measures. The pdf of the random variable maxx, y the max imum of the two. More precisely, given any time instance t, the query asks for the top k objects at time t with respect to some score attribute. Intuitively, treewidth measures how well the structure of a graph can be captured by a treelike. Cheriton school of computer science university of waterloo ecient processing of topk queries is a crucial requirement in many interactive environments that involve massive amounts of data. Parameterized algorithms and complexity is a natural way to cope with problems. For n items, an efficient sort algorithm would scale on in space and on log n in time.
In the shift bribery problem, we are given an election, a preferred candidate p, and a budget. A parameterized topk algorithm a for q is an algorithm that in an instance x, k of q produces the k best solutions for x, k. Apr 19, 2018 if one were not interested in approximation algorithms but still wanted to use top k counting rules, then one might seek fixedparameter tractable algorithms. Efficient parameterized algorithms for biopolymer structuresequence alignment article pdf available in ieeeacm transactions on computational biology and bioinformatics 34.
We then present an approach to approximate different ranking functions using our parameterized ranking functions, and to learn a ranking function from user preferences section 5. Design and implementation of applications over delay tolerant networks for disaster and battlefield environment, karthikeyan sachidanandam. A correction for this article has been appended to the pdf file. A good choice of the parameter c depends on the skew of the score. Keywords and phrases parameterized complexity, election control, optimal attack, optimal defense 1 introduction the problem of election control asks if it is possible for an external agent, usually. One of the most popular strategies to cope with nphard problems is that of parameterized complexity 12, 17, where the core idea is to identify a parameter k. As one of the core operations in data retrieval, we study top k queries with crowdsourcing, namely crowdenabled top k queries. The area of parameterized approximation seeks to combine approximation and parameterized algorithms to obtain, e. Since we are counting the top k, i believe that we could devise an algorithm that scales o k in space. A survey of topk query processing techniques in relational database systems ihab f.
Srinivas aluru and in the cheriton school of computer science, university of waterloo, canada with prof. While a large number of compression algorithms have been developed, there is no comprehensive and convenient. In particular, we show that for a large class of wellknown np optimization problems, there are parameterized top k algorithms that produce the best k solutions for the problems in feasible amount. Parameterized algorithms for generalized traveling salesman. Approximation and parameterized algorithms for common subtrees and edit distance between unordered trees tatsuya akutsu, daiji fukagawa, magnus m. Advanced techniques for improving canonical genetic programming, adam tyler harter. The book covers many of the recent developments of the field, including application of important. Theoretical computer science vol 470, pages 1120 28. First, we propose the best position algorithm bpa which executes topk queries much more efficiently than ta.
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