Operations on (ordered) interval sets

Intervals play an important role in various kinds of database-applications in practice, for example in historical, spatial, and temporal databases. As a consequence, there is a practical need for a clear and proper treatment of various useful operations on intervals and interval sets in a database context. However, the semantics of some important operations on interval sets are not always treated or not treated very clearly in the literature; e.g., often they are defined in an algorithmic rather than a declarative manner. Moreover, implementation proposals are often not as straightforward as they could be. This paper presents a declarative treatment of various operations on interval sets, also introducing some new notions (such as ordered interval sets, their visible points, and their surface). Then the paper formally ?links? such (mathematical) intervals to their database representations. Finally the paper provides straightforward translations from these formal database representations to standard SQL, without the need for SQL extensions.

A Spatio-Temporal Framework for Managing Archeological Data

Space and time are two important characteristics of data in many domains. This is particularly true in the archaeological context where informa- tion concerning the discovery location of objects allows one to derive important relations between findings of a specific survey or even of different surveys, and time aspects extend from the excavation time, to the dating of archaeological objects. In recent years, several attempts have been performed to develop a spatio-temporal information system tailored for archaeological data. The first aim of this paper is to propose a model, called Star, for repre- senting spatio-temporal data in archaeology. In particular, since in this domain dates are often subjective, estimated and imprecise, Star has to incorporate such vague representation by using fuzzy dates and fuzzy relationships among them. Moreover, besides to the topological relations, another kind of spatial relations is particularly useful in archeology: the stratigraphic ones. There- fore, this paper defines a set of rules for deriving temporal knowledge from the topological and stratigraphic relations existing between two findings. Finally, considering the process through which objects are usually manually dated by archeologists, some existing automatic reasoning techniques may be success- fully applied to guide such process. For this purpose, the last contribution regards the translation of archaeological temporal data into a Fuzzy Temporal Constraint Network for checking the overall data consistency and reducing the vagueness of some dates based on their relationships with other ones

Achieving a Sequenced, Relational Query Language with Log-Segmented Timestamps

In a relational temporal database, typically each row of each table has a period timestamp to indicate the lifetime of that row. In order to evaluate a query in a temporal database, sequenced semantics comes into play. The semantics stipulates that the query must be evaluated simultaneously in each time instant using the data rows available at that point of time. Existing researches have proposed changes in the query evaluation engine to achieve sequenced semantics. In this paper we show a way to support sequenced semantics without modifying the query engine. We propose a noble construction log-segmented label to represent the lifetime and replace the period timestamp from each row with a log-segmented label that signifies when the tuple is alive. Then we translate a sequenced query to a non-temporal query by utilizing the properties of log-segmented label. The translated query has only operations already available in a typical relational database making the query readily executable in an unaltered installation of the database. Thus the sequenced query inevitably runs and retrieve data without changing query evaluation engine. Finally our implementation using Java language, ANTLR parser generator and PostgreSQL database demonstrates the feasibility of the proposed mechanism, which, to the best of our knowledge, has not been previously shown

SOWL QL: Querying Spatio - Temporal Ontologies in OWL

We introduce SOWL QL, a query language for spatio-temporal information in ontologies. Buildingupon SOWL (Spatio-Temporal OWL), an ontology for handling spatio-temporal information in OWL, SOWL QL supports querying over qualitative spatio-temporal information (expressed using natural language expressions such as “before”, “after”, “north of”, “south of”) rather than merely quantitative information (exact dates, times, locations). SOWL QL extends SPARQL with a powerful set of temporal and spatial operators, including temporal Allen topological, spatial directional and topological operations or combinations of the above. SOWL QL maintains simplicity of expression and also, upward and downward compatibility with SPARQL. Query translation in SOWL QL yields SPARQL queries implying that, querying spatio-temporal ontologies using SPARQL is still feasible but suffers from several drawbacks the most important of them being that, queries in SPARQL become particularly complicated and users must be familiar with the underlying spatio-temporal representation (the “N-ary relations” or the “4D-fluents” approach in this work). Finally, querying in SOWL QL is supported by the SOWL reasoner which is not part of the standard SPARQL translation. The run-time performance of SOWL QL has been assessed experimentally in a real data setting. A critical analysis of its performance is also presented

Extending a set-theoretic implementation of Montague Semantics to accommodate n-ary transitive verbs.

Natural-language querying of databases remains an important and challenging area. Many approaches have been proposed over many years yet none of them has provided a comprehensive fully-compositional denotational semantics for a large sub-set of natural language, even for querying first-order non-intentional, non-modal, relational databases. One approach, which has made significant progress, is that which is based on Montague Semantics. Various researchers have helped to develop this approach and have demonstrated its viability. However, none have yet shown how to accommodate transitive verbs of arity greater than two. Our thesis is that existing approaches to the implementation of Montague Semantics in modern functional programming languages can be extended to solve this problem. This thesis is proven through the development of a compositional semantics for n-ary transitive verbs (n ≥ 2) and implementation in the Miranda programming environment. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2005 .R69. Source: Masters Abstracts International, Volume: 44-03, page: 1413. Thesis (M.Sc.)--University of Windsor (Canada), 2005