Temporal Database

A wide range of database applications manage information that varies over time. The conceptual modeling of databases is frequently based on one of the several versions of the ER model. As this model does not provide built-in means for capturing temporal aspects of data, the resulting diagrams are unnecessarily obscure and inadequate for documentation purposes. The TimeER model extends the ER model with suitable constructs for modeling time-varying information, easing the design process, and leading to easy-to-understand ...

Abstract—Tampering of a database can be detected through the use of cryptographically strong hash functions. Subsequently, applied forensic analysis algorithms can help determine when, what, and perhaps ultimately who and why. This paper presents a novel forensic analysis algorithm, the Tiled Bitmap Algorithm, which is more efficient than prior forensic analysis algorithms. It introduces the notion of a candidate set (all possible locations of detected tampering(s)) and provides a complete characterization of the candidate set and its cardinality. An optimal algorithm for computing the candidate set is also presented. Finally, the implementation of the Tiled Bitmap Algorithm is discussed, along with a comparison to other forensic algorithms in terms of space/time complexity and cost. An example of candidate set generation and proofs of the theorems and lemmata and of algorithm correctness can be found in the appendix, which can be found on the Computer Society Digital Library at

Abstract. Various temporal extensions to the relational model have been proposed. All of these, however, devi-ate significantly from the original relational model. This pa-per presents a temporal extension of the relational algebra that is not significantly different from the ...

GeoInformatica 5:1, 11±32, 2001 © 2001 Kluwer Academic Publishers. Manufactured in The Netherlands. ... Making Space for Time: Issues in Space-Time Data ... DONNA J. PEUQUET Department of Geography and The GeoVista Center, 302 Walker Building, The ...

This paper presents the initial stages of the design of a National Learning Objects Repository for Cyprus (NLORC). It examines the views of the faculty members of Intrecollege, a College of Higher Education in Cyprus, with regards to the need of such a repository. These views were collected through a questionnaire. The NLORC will provide a web-based application allowing indexing,

The changes that can be made to a document throughout its lifetime are limitless. Temporal management of documents with multiple versions is a complex area of research that has risen from the need to preserve information. Today s technology- driven society is rapidly moving towards web environments and using XML as the format of choice of information representation and exchange.

Abstract In bitemporal databases, current facts and transaction states are modeled using a special value to represent the current time (such as a minimum or maximum timestamp or NULL). Previous studies indicate that the choice of value for now (ie the current time) ...

Granularity is an integral feature of both anchored (eg, 25 October 1995, July 1996) and unanchored (eg, 3 minutes, 6 hours 20 minutes, 5 days) temporal data. In supporting temporal data that is specified in different granularities, numerous approaches have been proposed to deal with the issues of converting temporal data from one granularity to another. The emphasis, however, has only been on granularity conversions with respect to anchored temporal data. In this paper we provide a novel approach to the treatment of granularity in ...

Abstract: Time is one of the most difficult aspects to handle in real world applications such as database systems. Relational database management systems proposed by Codd offer very little built-in query language support for temporal data management. The model itself ...

Spatial and temporal (ST) databases have traditionally been used to manage geographic data. However, the human body is another important low dimensional physical space which is extensively measured, queried and analyzed in the field of medicine. Health care is fundamental to the lives of all people, young or old, rich or poor, healthy or ill. This is an opportune time

The ramification problem is a hard and ever present problem in systems exhibiting a dynamic behavior. The area of temporal databases in particular is still lacking satisfactory solutions to the ramification problem. In this paper, we address the ramification problem based on causal relationships that take time into account. We study the problem for both instantaneous actions and actions with duration. The proposed solution advances previous work by considering actions with effects occurring in any of the possible future situations resulting from an action's execution.

Abstract. Business Intelligence solutions, encompassing technologies such as multi-dimensional data modeling and aggregate query processing, are being applied increasingly to non-traditional data. This paper extends multi-dimensional aggregation to apply to data with associated interval values that capture when the data hold. In temporal databases, intervals typically capture the states of reality that the data apply to, or capture when the data are, or were, part of the current database state.

Visual object database browsers are essentially based on two kinds of interactions: navigation within a collection of objects, and navigation between objects via their relationships. These two interactional operators have proven to adequately support the main user task addressed by these tools, i.e. exploring the states of a set of related objects. In temporal object databases, visual browsing tools should additionally support users tasks such as studying a snapshot of a collection of objects at a given instant, or detecting and examining changes within object states. In this paper, we show that the two interactional operators supported by classical object browsers do not adequately address these tasks. We consequently propose an interactional operator dedicated to navigation through time, and we study how it can be orthogonally integrated with the above two. 1 Introduction Three main tasks involving intensive user interaction are classically identified in the context of data...

Ongoing climatic change on the Antarctic Peninsula is well documented in numerous scientific publications. Nevertheless, spatial and temporal distribution of glacier changes on the Antarctic Peninsula remain largely unknown. To analyse regional patterns and trends of changes in snow cover parameters on the Antarctic Peninsula north of 70° S, we propose a geostatistical approach based on the analysis of data derived by remote sensing methods. A time series of radar (ERS-1/2 SAR, Envisat ASAR and Radarsat SAR) and optical data (Landsat TM, Landsat ETM+ and Terra ASTER) enables the compilation of a multi-temporal database of glacier parameters for the last two decades. In this paper, we propose a method to facilitate the pre-processing and classification of remotely sensed data from several sources, and describe a sampling method used for selecting a representative set of glaciers for evaluation of classification algorithms. The so-called centreline approach facilitates pre-processing ...