Bulletin of the Society of Sea Water Science, Japan最新文献_第7页

Algorithms for new types of fair stable matchings 新型公平稳定匹配的算法

Bulletin of the Society of Sea Water Science, Japan Pub Date : 2020-01-29 DOI: 10.4230/LIPIcs.SEA.2020.20

Frances Cooper, D. Manlove

{"title":"Algorithms for new types of fair stable matchings","authors":"Frances Cooper, D. Manlove","doi":"10.4230/LIPIcs.SEA.2020.20","DOIUrl":"https://doi.org/10.4230/LIPIcs.SEA.2020.20","url":null,"abstract":"We study the problem of finding \"fair\" stable matchings in the Stable Marriage problem with Incomplete lists (SMI). For an instance $I$ of SMI there may be many stable matchings, providing significantly different outcomes for the sets of men and women. We introduce two new notions of fairness in SMI. Firstly, a regret-equal stable matching minimises the difference in ranks of a worst-off man and a worst-off woman, among all stable matchings. Secondly, a min-regret sum stable matching minimises the sum of ranks of a worst-off man and a worst-off woman, among all stable matchings. We present two new efficient algorithms to find stable matchings of these types. Firstly, the Regret-Equal Degree Iteration Algorithm finds a regret-equal stable matching in $O(d_0 nm)$ time, where $d_0$ is the absolute difference in ranks between a worst-off man and a worst-off woman in the man-optimal stable matching, $n$ is the number of men or women, and $m$ is the total length of all preference lists. Secondly, the Min-Regret Sum Algorithm finds a min-regret sum stable matching in $O(d_s m)$ time, where $d_s$ is the difference in the ranks between a worst-off man in each of the woman-optimal and man-optimal stable matchings. Experiments to compare several types of fair optimal stable matchings were conducted and show that the Regret-Equal Degree Iteration Algorithm produces matchings that are competitive with respect to other fairness objectives. On the other hand, existing types of \"fair\" stable matchings did not provide as close an approximation to regret-equal stable matchings.","PeriodicalId":9448,"journal":{"name":"Bulletin of the Society of Sea Water Science, Japan","volume":"5 1","pages":"20:1-20:13"},"PeriodicalIF":0.0,"publicationDate":"2020-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84661066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Path Query Data Structures in Practice 路径查询数据结构实践

Bulletin of the Society of Sea Water Science, Japan Pub Date : 2020-01-28 DOI: 10.4230/LIPIcs.SEA.2020.27

Meng He, Serikzhan Kazi

{"title":"Path Query Data Structures in Practice","authors":"Meng He, Serikzhan Kazi","doi":"10.4230/LIPIcs.SEA.2020.27","DOIUrl":"https://doi.org/10.4230/LIPIcs.SEA.2020.27","url":null,"abstract":"We perform experimental studies on data structures that answer path median, path counting, and path reporting queries in weighted trees. These query problems generalize the well-known range median query problem in arrays, as well as the $2d$ orthogonal range counting and reporting problems in planar point sets, to tree structured data. We propose practical realizations of the latest theoretical results on path queries. Our data structures, which use tree extraction, heavy-path decomposition and wavelet trees, are implemented in both succinct and pointer-based form. Our succinct data structures are further specialized to be plain or entropy-compressed. Through experiments on large sets, we show that succinct data structures for path queries may present a viable alternative to standard pointer-based realizations, in practical scenarios. Compared to na{\"i}ve approaches that compute the answer by explicit traversal of the query path, our succinct data structures are several times faster in path median queries and perform comparably in path counting and path reporting queries, while being several times more space-efficient. Plain pointer-based realizations of our data structures, requiring a few times more space than the na{\"i}ve ones, yield up to $100$-times speed-up over them.","PeriodicalId":9448,"journal":{"name":"Bulletin of the Society of Sea Water Science, Japan","volume":"65 1","pages":"27:1-27:16"},"PeriodicalIF":0.0,"publicationDate":"2020-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86837018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

High-Quality Hierarchical Process Mapping 高质量层次过程映射

Bulletin of the Society of Sea Water Science, Japan Pub Date : 2020-01-20 DOI: 10.4230/LIPIcs.SEA.2020.4

Marcelo Fonseca Faraj, Alexander van der Grinten, Henning Meyerhenke, J. Träff, Christian Schulz

{"title":"High-Quality Hierarchical Process Mapping","authors":"Marcelo Fonseca Faraj, Alexander van der Grinten, Henning Meyerhenke, J. Träff, Christian Schulz","doi":"10.4230/LIPIcs.SEA.2020.4","DOIUrl":"https://doi.org/10.4230/LIPIcs.SEA.2020.4","url":null,"abstract":"Partitioning graphs into blocks of roughly equal size such that few edges run between blocks is a frequently needed operation when processing graphs on a parallel computer. When a topology of a distributed system is known an important task is then to map the blocks of the partition onto the processors such that the overall communication cost is reduced. We present novel multilevel algorithms that integrate graph partitioning and process mapping. Important ingredients of our algorithm include fast label propagation, more localized local search, initial partitioning, as well as a compressed data structure to compute processor distances without storing a distance matrix. Experiments indicate that our algorithms speed up the overall mapping process and, due to the integrated multilevel approach, also find much better solutions in practice. For example, one configuration of our algorithm yields better solutions than the previous state-of-the-art in terms of mapping quality while being a factor 62 faster. Compared to the currently fastest iterated multilevel mapping algorithm Scotch, we obtain 16% better solutions while investing slightly more running time.","PeriodicalId":9448,"journal":{"name":"Bulletin of the Society of Sea Water Science, Japan","volume":"70 1","pages":"4:1-4:15"},"PeriodicalIF":0.0,"publicationDate":"2020-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73834135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 7

Fast and Stable Repartitioning of Road Networks 快速稳定的道路网络重新划分

Bulletin of the Society of Sea Water Science, Japan Pub Date : 2020-01-01 DOI: 10.4230/LIPIcs.SEA.2020.26

V. Buchhold, D. Delling, D. Schieferdecker, Michael Wegner

引用次数: 2

Engineering Fused Lasso Solvers on Trees 树木上的工程融合套索求解器

Bulletin of the Society of Sea Water Science, Japan Pub Date : 2020-01-01 DOI: 10.4230/LIPIcs.SEA.2020.23

Elias Kuthe, S. Rahmann

{"title":"Engineering Fused Lasso Solvers on Trees","authors":"Elias Kuthe, S. Rahmann","doi":"10.4230/LIPIcs.SEA.2020.23","DOIUrl":"https://doi.org/10.4230/LIPIcs.SEA.2020.23","url":null,"abstract":"The graph fused lasso optimization problem seeks, for a given input signal y = (yi) on nodes i ∈ V of a graph G = (V,E), a reconstructed signal x = (xi) that is both element-wise close to y in quadratic error and also has bounded total variation (sum of absolute differences across edges), thereby favoring regionally constant solutions. An important application is denoising of spatially correlated data, especially for medical images. Currently, fused lasso solvers for general graph input reduce the problem to an iteration over a series of “one-dimensional” problems (on paths or line graphs), which can be solved in linear time. Recently, a direct fused lasso algorithm for tree graphs has been presented, but no implementation of it appears to be available. We here present a simplified exact algorithm and additionally a fast approximation scheme for trees, together with engineered implementations for both. We empirically evaluate their performance on different kinds of trees with distinct degree distributions (simulated trees; spanning trees of road networks, grid graphs of images, social networks). The exact algorithm is very efficient on trees with low node degrees, which covers many naturally arising graphs, while the approximation scheme can perform better on trees with several higher-degree nodes when limiting the desired accuracy to values that are useful in practice. 2012 ACM Subject Classification Theory of computation → Mathematical optimization; Theory of computation → Dynamic programming; Mathematics of computing → Trees","PeriodicalId":9448,"journal":{"name":"Bulletin of the Society of Sea Water Science, Japan","volume":"47 1","pages":"23:1-23:14"},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80736379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Effect of Initial Assignment on Local Search Performance for Max Sat 初始分配对最大卫星局部搜索性能的影响

Bulletin of the Society of Sea Water Science, Japan Pub Date : 2020-01-01 DOI: 10.4230/LIPIcs.SEA.2020.8

D. Berend, Yochai Twitto

{"title":"Effect of Initial Assignment on Local Search Performance for Max Sat","authors":"D. Berend, Yochai Twitto","doi":"10.4230/LIPIcs.SEA.2020.8","DOIUrl":"https://doi.org/10.4230/LIPIcs.SEA.2020.8","url":null,"abstract":"In this paper, we explore the correlation between the quality of initial assignments provided to local search heuristics and that of the corresponding final assignments. We restrict our attention to the Max r-Sat problem and to one of the leading local search heuristics – Configuration Checking Local Search (CCLS). We use a tailored version of the Method of Conditional Expectations (MOCE) to generate initial assignments of diverse quality. We show that the correlation in question is significant and long-lasting. Namely, even when we delve deeper into the local search, we are still in the shadow of the initial assignment. Thus, under practical time constraints, the quality of the initial assignment is crucial to the performance of local search heuristics. To demonstrate our point, we improve CCLS by combining it with MOCE. Instead of starting CCLS from random initial assignments, we start it from excellent initial assignments, provided by MOCE. Indeed, it turns out that this kind of initialization provides a significant improvement of this state-of-the-art solver. This improvement becomes more and more significant as the instance grows. 2012 ACM Subject Classification Theory of computation→ Theory of randomized search heuristics; Theory of computation → Stochastic approximation","PeriodicalId":9448,"journal":{"name":"Bulletin of the Society of Sea Water Science, Japan","volume":"172 1","pages":"8:1-8:14"},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90230749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Algorithm Engineering for High-Dimensional Similarity Search Problems (Invited Talk) 高维相似搜索问题的算法工程(特邀演讲)

Bulletin of the Society of Sea Water Science, Japan Pub Date : 2020-01-01 DOI: 10.4230/LIPIcs.SEA.2020.1

Martin Aumüller

{"title":"Algorithm Engineering for High-Dimensional Similarity Search Problems (Invited Talk)","authors":"Martin Aumüller","doi":"10.4230/LIPIcs.SEA.2020.1","DOIUrl":"https://doi.org/10.4230/LIPIcs.SEA.2020.1","url":null,"abstract":"Similarity search problems in high-dimensional data arise in many areas of computer science such as data bases, image analysis, machine learning, and natural language processing. One of the most prominent problems is finding the k nearest neighbors of a data point q ∈ ℝ^d in a large set of data points S ⊂ ℝ^d, under same distance measure such as Euclidean distance. In contrast to lower dimensional settings, we do not know of worst-case efficient data structures for such search problems in high-dimensional data, i.e., data structures that are faster than a linear scan through the data set. However, there is a rich body of (often heuristic) approaches that solve nearest neighbor search problems much faster than such a scan on many real-world data sets. As a necessity, the term solve means that these approaches give approximate results that are close to the true k-nearest neighbors. In this talk, we survey recent approaches to nearest neighbor search and related problems. The talk consists of three parts: (1) What makes nearest neighbor search difficult? (2) How do current state-of-the-art algorithms work? (3) What are recent advances regarding similarity search on GPUs, in distributed settings, or in external memory?","PeriodicalId":9448,"journal":{"name":"Bulletin of the Society of Sea Water Science, Japan","volume":"78 1","pages":"1:1-1:3"},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82848492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Algorithm Engineering for Sorting and Searching, and All That (Invited Talk) 排序和搜索的算法工程，以及所有这些(特邀演讲)

Bulletin of the Society of Sea Water Science, Japan Pub Date : 2020-01-01 DOI: 10.4230/LIPIcs.SEA.2020.2

S. Edelkamp

引用次数: 0

Finding Structurally and Temporally Similar Trajectories in Graphs 在图中寻找结构和时间上相似的轨迹

Bulletin of the Society of Sea Water Science, Japan Pub Date : 2020-01-01 DOI: 10.4230/LIPIcs.SEA.2020.24

R. Grossi, Andrea Marino, Shima Moghtasedi

引用次数: 3

Indexing Compressed Text: A Tale of Time and Space (Invited Talk) 索引压缩文本:时间与空间的故事(特邀演讲)

Bulletin of the Society of Sea Water Science, Japan Pub Date : 2020-01-01 DOI: 10.4230/LIPIcs.SEA.2020.3

N. Prezza

{"title":"Indexing Compressed Text: A Tale of Time and Space (Invited Talk)","authors":"N. Prezza","doi":"10.4230/LIPIcs.SEA.2020.3","DOIUrl":"https://doi.org/10.4230/LIPIcs.SEA.2020.3","url":null,"abstract":"Text indexing is a classical algorithmic problem that has been studied for over four decades. The earliest optimal-time solution to the problem, the suffix tree [11], dates back to 1973 and requires up to two orders of magnitude more space than the text to be stored. In the year 2000, two breakthrough works [6, 3] showed that this space overhead is not necessary: both the index and the text can be stored in a space proportional to the text’s entropy. These contributions had an enormous impact in bioinformatics: nowadays, the two most widely-used DNA aligners employ compressed indexes [9, 8]. In recent years, it became apparent that entropy had reached its limits: modern datasets (for example, collections of thousands of human genomes) are extremely large but very repetitive and, by its very definition, entropy cannot compress repetitive texts [7]. To overcome this problem, a new generation of indexes based on dictionary compressors (for example, LZ77 and run-length BWT) emerged [7, 5, 1], together with generalizations of the indexing problem to labeled graphs [2, 10, 4]. This talk is a short and friendly survey of the landmarks of this fascinating path that took us from suffix trees to the most modern compressed indexes on labeled graphs. 2012 ACM Subject Classification Theory of computation → Data compression; Theory of computation → Sorting and searching; Theory of computation → Pattern matching","PeriodicalId":9448,"journal":{"name":"Bulletin of the Society of Sea Water Science, Japan","volume":"261 1","pages":"3:1-3:2"},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76253699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0