Topic
Tuple
About: Tuple is a research topic. Over the lifetime, 6513 publications have been published within this topic receiving 146057 citations. The topic is also known as: tuple & ordered tuplet.
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02 Jul 1979
TL;DR: Within the framework of net-semantics of models of dynamic systems, a new standard interpretation of nets are introduced called predicate/transition-nets (Pr/T-nets), which are schemes of ‘ordinary’ Petri nets.
Abstract: Within the framework of net-semantics of models of dynamic systems, the present paper introduces a new standard interpretation of nets called predicate/transition-nets (Pr/T-nets). These nets are schemes of ‘ordinary’ Petri nets. The places (circles) of Pr/T-nets represent changing properties of, or relations between, individuals; they are ‘predicates’ with variable extension. A current case of a system modelled by a Pr/T-net is denoted by marking the places with those tuples of individual symbols for which the respective predicates hold in that case. The transitions (boxes) are schemes of elementary changes of markings constituting the processes carried by the system. Instances of these schemes are generated by means of consistent substitution of individual variables by symbols.
151 citations
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01 Mar 1988TL;DR: This paper designs a sampling plan based on the cluster sampling method to improve the utilization of sampled data and to reduce the cost of sampling, and proposes consistent and unbiased estimators for arbitrary COUNT(E) type queries.
Abstract: Present database systems process all the data related to a query before giving out responses. As a result, the size of the data to be processed becomes excessive for real-time/time-constrained environments. A new methodology is needed to cut down systematically the time to process the data involved in processing the query. To this end, we propose to use data samples and construct an approximate synthetic response to a given query.In this paper, we consider only COUNT(E) type queries, where E is an arbitrary relational algebra expression. We make no assumptions about the distribution of attribute values and ordering of tuples in the input relations, and propose consistent and unbiased estimators for arbitrary COUNT(E) type queries. We design a sampling plan based on the cluster sampling method to improve the utilization of sampled data and to reduce the cost of sampling. We also evaluate the performance of the proposed estimators.
150 citations
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TL;DR: A class of extended CRPQs, called ECRPZs, are proposed, which add regular relations on tuples of paths, and allow path variables in the heads of queries, and are studied for their usefulness in querying graph structured data.
Abstract: For many problems arising in the setting of graph querying (such as finding semantic associations in RDF graphs, exact and approximate pattern matching, sequence alignment, etc.), the power of standard languages such as the widely studied conjunctive regular path queries (CRPQs) is insufficient in at least two ways. First, they cannot output paths and second, more crucially, they cannot express relationships among paths.We thus propose a class of extended CRPQs, called ECRPQs, which add regular relations on tuples of paths, and allow path variables in the heads of queries. We provide several examples of their usefulness in querying graph structured data, and study their properties. We analyze query evaluation and representation of tuples of paths in the output by means of automata. We present a detailed analysis of data and combined complexity of queries, and consider restrictions that lower the complexity of ECRPQs to that of relational conjunctive queries. We study the containment problem, and look at further extensions with first-order features, and with nonregular relations that add arithmetic constraints on the lengths of paths and numbers of occurrences of labels.
149 citations
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14 Sep 2012TL;DR: In this article, techniques for extracting information from a database such as the Web are described. But they do not address the problem of identifying a pattern in which the tuples of information were stored.
Abstract: Techniques for extracting information from a database are provided. A database such as the Web is searched for occurrences of tuples of information. The occurrences of the tuples of information that were found in the database are analyzed to identify a pattern in which the tuples of information were stored. Additional tuples of information can then be extracted from the database utilizing the pattern. This process can be repeated with the additional tuples of information, if desired.
149 citations
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10 Sep 2000TL;DR: This paper introduces icicles, a new class of samples that tune themselves to a dynamic workload and shows, analytically, that for a certain class of queries reflected by the workload, icicles yield more accurate answers.
Abstract: Approximate query answering systems provide very fast alternatives to OLAP systems when applications are tolerant to small errors in query answers. Current sampling-based approaches to approximately answer aggregate queries over foreign key joins suffer from the following drawback. All tuples in relations are deemed equally important for answering queries even though, in reality, OLAP queries exhibit locality in their data access. Consequently, they may waste precious real estate by sampling tuples that are not required at all or required very rarely. In this paper, we introduce icicles, a new class of samples that tune themselves to a dynamic workload. Intuitively, the probability of a tuple being present in an icicle is proportional to its importance for answering queries in the workload. Therefore, an icicle consists of more tuples from a subset of the relation that is required to answer more queries in the workload. Consequently, the accuracy of approximate answers obtained by using icicles is better than a static uniform random sample. We show, analytically, that for a certain class of queries reflected by the workload, icicles yield more accurate answers. In a detailed experimental study, we examine the validity and performance of icicles.
148 citations