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.
Papers published on a yearly basis
Papers
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16 May 2012TL;DR: In this article, a multi-dimensional OLAP query processing method oriented to a column store data warehouse is described, which is divided into a bitmap filtering operation, a group-by operation and an aggregate operation.
Abstract: A multi-dimensional OLAP query processing method oriented to a column store data warehouse is described. With this method, an OLAP query is divided into a bitmap filtering operation, a group-by operation and an aggregate operation. In the bitmap filtering operation, a predicate is first executed on a dimension table to generate a predicate vector bitmap, and a join operation is converted, through address mapping of a surrogate key, into a direct dimension table tuple access operation; in the group-by operation, a fact table tuple satisfying a filtering condition is pre-generated into a group-by unit according to a group-by attribute in an SQL command and is allocated with an increasing ID; and in the aggregate operation, group-by aggregate calculation is performed according to a group item of a fact table filtering group-by vector through one-pass column scan on a fact table measure attribute.
33 citations
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TL;DR: A new multiple attribute decision making approach for dealing with 2-Tuple linguistic information, called the 2-tuple linguistic induced generalized ordered weighted averaging distance (2LIGOWAD) operator, is developed and an application is presented to a group decision making problem about selection of strategies.
33 citations
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10 Oct 2019TL;DR: This paper presents APALACHE -- a first symbolic model checker for TLA+.
Abstract: TLA+ is a language for formal specification of all kinds of computer systems. System designers use this language to specify concurrent, distributed, and fault-tolerant protocols, which are traditionally presented in pseudo-code. TLA+ is extremely concise yet expressive: The language primitives include Booleans, integers, functions, tuples, records, sequences, and sets thereof, which can be also nested. This is probably why the only model checker for TLA+ (called TLC) relies on explicit enumeration of values and states. In this paper, we present APALACHE -- a first symbolic model checker for TLA+. Like TLC, it assumes that all specification parameters are fixed and all states are finite structures. Unlike TLC, APALACHE translates the underlying transition relation into quantifier-free SMT constraints, which allows us to exploit the power of SMT solvers. Designing this translation is the central challenge that we address in this paper. Our experiments show that APALACHE outperforms TLC on examples with large state spaces.
33 citations
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TL;DR: It is suggested that through XMDL, the practical development of such complex systems can be split into two separate activities: (a) the modelling of stand-alone X-machine components and (b) the description of the communication between these components.
Abstract: An X-machine is a general computational machine that can model: (a) non-trivial data structures as a typed memory tuple and (b) the dynamic part of a system by employing transitions, which are not labelled with simple inputs but with functions that operate on inputs and memory values. The X-machine formal method is valuable to software engineers since it is rather intuitive, while at the same time formal descriptions of data types and functions can be written in any known mathematical notation. These differences allow the X-machines to be more expressive and flexible than a Finite State Machine. In addition, a set of X-machines can be viewed as components, which communicate with each other in order to specify larger systems. This paper describes a methodology as well as an appropriate notation, namely X-machine Description Language (XMDL), for building communicating X-machines from existing stand-alone X-machine models. The proposed methodology is accompanied by an example model of a traffic light junction, which demonstrates the use of communicating X-machines towards the incremental modelling of large-scale systems. It is suggested that through XMDL, the practical development of such complex systems can be split into two separate activities: (a) the modelling of stand-alone X-machine components and (b) the description of the communication between these components. The approach is disciplined, practical, modular and general in the sense that it subsumes the existing methods for communicating X-machines.
33 citations
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01 May 1983TL;DR: New procedures to handle cyclic queries utilizing dependencies and horizontal decompositions are discussed and Tuple-wise processing and attribute addition are shown to be special cases of the FD-based procedure.
Abstract: Since join operations are expensive, usually join scheduling is very important for query processing. In this paper we will discuss new procedures to handle cyclic queries utilizing dependencies and horizontal decompositions. There are three known procedures for cyclic query processing: (1) Relation merging, (2) Tuple-wise processing, (3) Attribute addition. As join operations are applied to relations which are processed by selection operations, the number of tuples is usually less than the original relation and thus there are situations in which temporary FDs are satisfied. Such FDs can be used to simplify the given query. To convert a given cyclic query into a tree, some relations must satisfy a set of FDs. This can be attained by horizontal decomposition. Tuple-wise processing and attribute addition are shown to be special cases of the FD-based procedure. We have also developed MVD-based procedures which are generalized from the FD-based procedure.
33 citations