A theoretical model for crisp and fuzzy time

Billiet

Flexible Approaches in Data, Information and Knowledge Management

et al. 2013

In reality, some objects or concepts have properties with a time-variant or time-related nature. Modelling these kinds of objects or concepts in a (relational) database schema is possible, but time-variant and time-related attributes have an impact on the consistency of the entire database. Therefore, temporal database models have been proposed to deal with this. Time itself can be at the source of imprecision, vagueness and uncertainty, since existing time measuring devices are inherently imperfect. Accordingly, human beings manage time using temporal indications and temporal notions, which may contain imprecision, vagueness and uncertainty. However, the imperfection in human-used temporal indications is supported by human interpretation, whereas information systems need extraordinary support for this. Several proposals for dealing with such imperfections when modelling temporal aspects exist. Some of these proposals consider the basis of the system to be the conversion of the specificity of temporal notions between used temporal expressions. Other proposals consider the temporal indications in the used temporal expressions to be the source of imperfection. In this chapter, an overview is given, concerning the basic concepts and issues related to the modelling of time as such or in (relational) database models and the imperfections that may arise during or as a result of this modelling. Next to this, a novel and currently researched technique for handling some of these imperfections is presented.

Section: Types Of Imperfections In Temporal Modellingmentioning

confidence: 99%

Section: Representation Of Imperfect Informationmentioning

confidence: 99%

See 1 more Smart Citation

Aspects of Dealing with Imperfect Data in Temporal Databases

Billiet

Flexible Approaches in Data, Information and Knowledge Management

et al. 2013

Proceedings of the 8th Conference of the European Society for Fuzzy Logic and Technology

“…To achieve this modelling, IS contain data representing properties of real-world objects or concepts [1], [2]. As time is an essential aspect of many real-world objects or concepts, IS often contain data representing temporal notions which describe such temporal properties [3], [4]. Such temporal notions usually take the form of either instants [5], which can informally be seen as infinitely short 'moments' or 'points' in time, or time intervals [5].…”

Section: Introductionmentioning

confidence: 99%

A Comparison of Approaches to Model Uncertainty in Time Intervals

Billiet¹,

Pons²,

Pons³

et al. 2013

Information systems model parts of reality by representing properties of real-world objects or concepts. As real objects or concepts often have temporal aspects, temporal notions such as time intervals are often represented. However, these may contain imperfections like uncertainties, complicating their representations. A very important purpose of information systems is to be able to query them to retrieve information, but representations of temporal notions containing uncertainties severely complicate querying. Thus, several soft computing techniques have been proposed to represent time intervals subject to uncertainties in a semantically sound way and to reason with them in a semantically sound and useful way. In the presented work, two frameworks designed for this are compared. It is found that, despite slight differences in the way these frameworks represent intervals, they provide the same results when reasoning about time intervals subject to uncertainty.

“…As information systems attempt the modelling of natural objects, concepts or processes, they often require modelling temporal aspects or concepts. Thus, several proposals have arisen to obtain theoretical models that allow the modelling or representation of time 3,8 .…”

Section: Introductionmentioning

confidence: 99%

A Relational Model for the Possibilistic Valid-time Approach

Pons¹,

Marín²,

Pons³

et al. 2012

IJCIS

In real world, it is very common that some objects or concepts have properties with a time-variant or timerelated nature. Modelling this kind of objects or concepts in a (relational) database schema is possible, but time-variant and time-related attributes have an impact on the consistency of the entire database and must be appropriately managed. Therefore, temporal database models have been proposed to deal with this problem in the literature. Time can be affected by imprecision, vagueness and / or uncertainty, since existing time measuring devices are inherently imperfect. Additionally, human beings manage time using temporal indications and temporal notions, which may also be imprecise. However, the imperfection in human-used temporal indications is supported by human interpretation, whereas information systems need appropriate support in order to accomplish this task. Several proposals for dealing with such imperfections when modelling temporal data exist. Some of these proposals transform the temporal data into a compact representation but there is not a formal model for managing and handling uncertainty regarding temporal information. In this work we present a novel model to deal with imprecision in valid-time databases together with the definition and implementation of the data manipulation language, DML.