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REWERSE – WG A1: Event, Temporal, and Geographical Data

Internal homepage of the REWERSE working group A1 on Web-based Decision Support for Event, Temporal, and Geographical Data.


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Enhancing Event, Temporal, and Location Reasoning on the Web:
WG A1 investigates common-sense forms of reasoning that are relevant to most advanced and adaptive Web systems, i.e. reasoning with events, time, and locations.

Description of Work

With geotemporal information we mean any kind of temporal information that is based on some established human calendar system plus real-life temporal reference points such as events ("last Sunday", "begin of easter holidays", "WC-finals", "next elections", etc.) seasons ("early spring", "late summer" etc.) as well as epochs in history ("middle ages", "Roman empire", "second world war" etc.). The kind of temporal information that we want to address includes time points, intervals, durations and periodicities ("every second year"). We speak of "geo"temporal information since we do not focus on the temporal behaviour of microsystems, algorithmic processes, etc.

With geospatial information we mean any kind of spatial information that is based on an established system of geographic coordinates and on real-life locations such as countries, cities, places, rivers, etc. The kind of spatial information that we address includes geographic positions, distances, directions, and relations such as neighbourhood, inclusion etc.

With topical information we mean any orientation scheme that helps to position information in a suitable hierarchy of thematic fields, areas, domains and topics. Examples of general topics are "arts", "sports", "entertainment", examples of specific topics are "generation of electricity", "photographic equipment", "personal security". Topical information is ordered and represented in taxonomies and classification schemes such as, e.g., the UDC (universal decimal classification).

Already in the actual Web we find an enormous amount of information systems and services that deal with suitable combinations of temporal, geographic and topical data of the above form. One category of Web pages supports hotel booking offering suitable menus for selecting towns, places within towns, travel dates, price categories etc. Other Web pages offer informations about locations, dates and thematic areas of trade fairs or scientific conferences in various countries of the world. A third group of Web pages describe transport enterprises and services in terms of the kind of items that may be transported and the temporal and geographic restrictions that must be respected. Yet another kind of services offers actual news, following a systematics for topical and geographic filtering. In the present form, all these systems are designed or the human user. In most cases, automated access to the temporal, spatial and topical information is difficult or impossible, and for specifying temporal, geospatial and thematic conditions, only a small number of predefined choices ordered in menus exist.

A substantial progress for automated processing of Web contents - such as envisaged in many scenarios for the Semantic Web - can be expected from special reasoning mechanisms that are able to deal with temporal, geospatial and topical data. Most importantly, these mechanisms should satisfy two requirements: First, they should support a flexible matching and translation between temporal, spatial and topical conditions that are expressed in different ways. This task includes the interpretation of semi-formal and natural language expressions. Second, they should offer algorithms for solving these constraints. Matching formalisms provide an interface between conditions or queries formulated by a human or robot client on one side and properties/constraints/offers that are found in Web pages of enterprises or inquiry offices on the other side. Constraint solvers may then be used to establish compatibility of the requirements and to enumerate possible solutions . Furthermore, matching mechanisms and special constraint solvers for geotemporal, geospatial and topical information may be used to enhance "syntactic" mechanisms of general query languages for the Web - as they will be developed in REWERSE - with flexible "semantic" reasoning facilities for a broad range of applications.

Formal ontologies that collect and order distinct temporal and spatial notions and relate concepts represent an important prerequisite for common-sense geotemporal and geospatial reasoning, in particular they are indispensable for the above mentioned matching and translation techniques. Obviously, conventional temporal and spatial coordinate systems represent a backbone for these ontologies. But geotemporal and geospatial references found in Web pages and inquiries are often not expressed in explicit coordinates. Most references to locations are based on "named geo-entities" such as countries, cities,places, streets, oceans, rivers etc. Similarly temporal reference is often based on named singular or periodical events. Examples are calendar events (easter, Christmas, ramadan), holidays, political events (elections), sport events (world championships), scientific events and business events ("immediately after CADE", "two weeks before the IAA"). Events of the latter type also carry important topical information. Hence formal ontologies are needed that yield a bridge between standardised calendar systems and geo-coordinate systems on the one hand and temporal or locational expressions that are found in natural language, anchor texts or element names on the other hand. For topical classification of Web pages, besides events also other named entities can be important indicators (the ACM, the UN, BMW, etc.).

In Workpackage A1, suitable ontologies for geotemporal and geospatial notions and concepts will be built. On this basis, matching and constraint solving mechanisms for temporal and spatial reasoning will be realized. A thesaurus for events will be constructed that describes real-world events and positions them in a temporal-spatial-topical hierarchy. The construction of the hierarchy is a part of this task. A Web-based appointment scheduling system will be realised for proof-of-concept of the ontologies and reasoning mechanisms.

Contact information

Hans Jürgen Ohlbach , Bernhard Lorenz
Edgar Stoffel

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