Marcirio Silveira Chaves

Adding Geographic Scopes to Web Resources

Many web pages are rich in geographic information and primarily relevant to geographically limited communities. However, existing IR systems only recently began to offer local services and largely ignore geo-spatial information. This paper presents our work on automatically identifying the geographical scope of web documents, which provides the means to develop retrieval tools that take the geographical context into consideration. Our approach makes extensive use of an ontology of geographical concepts, and includes a system architecture for extracting geographic information from large collections of web documents. The proposed method involves recognising geographical references over the documents and assigning geographical scopes through a graph ranking algorithm. Initial evaluation results are encouraging, indicating the viability of this approach.

The University of Lisbon at GeoCLEF 2006

This paper details the participation of the XLDB Group from the University of Lisbon at the 2006 GeoCLEF task. We tested text mining methods that use an ontology to extract geographic references from text, assigning documents to encompassing geographic scopes. These scopes are used in document retrieval through a ranking function that combines BM25 text weighting with a similarity function for geographic scopes. We also tested a topic augmentation method, based on the geographic ontology, as an alternative to the scope-based approach.

Challenges and resources for evaluating geographical IR

This paper discusses evaluation of Geo-IR systems, arguing for a separate study of the different algorithmic components involved. It presents existing resources for evaluating the different components, together with a review on previous results in the area.

The XLDB group at GeoCLEF 2005

This paper describes our participation at GeoCLEF 2005. We detail the main software components of our Geo-IR system, its adaptation for GeoCLEF and the obtained results. The software architecture includes a geographic knowledge base, a text mining tool for geo-referencing documents, and a geo-ranking component. Results show that geo-ranking is heavily dependent on the information in the knowledge base and on the ranking algorithm involved.

Geo linked data

Semantic Web applications that include map visualization clients are becoming common. When the description of an entity contains coordinate pairs, semantic applications often lay them as pins on maps provided by Web mapping service applications, such as Google Maps. Nowadays, semantic applications cannot guarantee that those maps provide spatial information related to the entities pinned to them. To address this issue, this paper proposes a refinement of Linked Data practices, named Geo Linked Data, which defines a lightweight semantic infrastructure to relate URIs that identify real world entities with geospatial Web resources, such as maps.

Assigning Geographical Scopes To Web Pages

Finding automatic ways of attaching geographical scopes to on-line resources, also called “geo-referencing” documents, is a challenging problem, getting increasing attention [1,5,3]. Here we present a system architecture and a process for identifying the geographical scope of Web pages, defining a scope as the region where more people than average would find that page relevant. We rely on typical Web IR heuristics (i.e. feature weighting, hypertext topic locality, anchor description) and assumptions on how people use geographical references in documents. The method involves three major steps. First, geographical named entities are identified in the text. Next, we propagate the found named entities through the Web linkage graph. Finally, a geographical ontology is used to disambiguate among the named entities associated to a document, this way selecting the most likely scope. In the future, we plan on using scopes in new location-aware search tools.

Using Geographic Signatures as Query and Document Scopes in Geographic IR

This paper reports the participation of the University of Lisbon at the 2007 GeoCLEF task. We adopted a novel approach for GIR, focused on handling geographic features and feature types on both queries and documents, generating signatures with multiple geographic concepts as a scope of interest. We experimented new query expansion and text mining strategies, relevance feedback approaches and ranking metrics.

Linkable geographic ontologies

The performance of some tasks in Information Retrieval is strongly related to the extent and quality of the geographic knowledge about named places. This paper presents a conceptualization of the geographic knowledge, the Geo-Net vocabulary, and a tool for building large knowledge bases of named places, the GKB management system, developed in the GREASE-II project. The Geo-Net vocabulary is a conceptual model for describing geographic places, including their names, types, relationships and footprints. It uses URIs and the RDF data model to expose, share and connect pieces of geographic knowledge each other and to related data on the Web. The GKB system is a multi-paradigm knowledge management system that enables the development of geographic ontologies with the Geo-Net vocabulary. This paper also presents a geographic ontology of Portugal, Geo-Net-PT 02, created with the Geo-Net vocabulary and the GKB system.

What kinds of geographical information are there in the portuguese web

This paper presents some results about the geographical information in the Portuguese web and the overlap with peoples and organizations named entities, using a geographic ontology based on authoritative sources and a named entity recognizer.