SWI-Prolog and the Web

Where Prolog is commonly seen as a component in a Web application that is either embedded or communicates using a proprietary protocol, we propose an architecture where Prolog communicates to other components in a Web application using the standard HTTP protocol. By avoiding embedding in external Web servers development and deployment become much easier. To support this architecture, in addition to the transfer protocol, we must also support parsing, representing and generating the key Web document types such as HTML, XML and RDF. This paper motivates the design decisions in the libraries and extensions to Prolog for handling Web documents and protocols. The design has been guided by the requirement to handle large documents efficiently. The described libraries support a wide range of Web applications ranging from HTML and XML documents to Semantic Web RDF processing. To appear in Theory and Practice of Logic Programming (TPLP)Comment: 31 pages, 24 figures and 2 tables. To appear in Theory and Practice of Logic Programming (TPLP

Ranking Archived Documents for Structured Queries on Semantic Layers

Archived collections of documents (like newspaper and web archives) serve as important information sources in a variety of disciplines, including Digital Humanities, Historical Science, and Journalism. However, the absence of efficient and meaningful exploration methods still remains a major hurdle in the way of turning them into usable sources of information. A semantic layer is an RDF graph that describes metadata and semantic information about a collection of archived documents, which in turn can be queried through a semantic query language (SPARQL). This allows running advanced queries by combining metadata of the documents (like publication date) and content-based semantic information (like entities mentioned in the documents). However, the results returned by such structured queries can be numerous and moreover they all equally match the query. In this paper, we deal with this problem and formalize the task of "ranking archived documents for structured queries on semantic layers". Then, we propose two ranking models for the problem at hand which jointly consider: i) the relativeness of documents to entities, ii) the timeliness of documents, and iii) the temporal relations among the entities. The experimental results on a new evaluation dataset show the effectiveness of the proposed models and allow us to understand their limitation

RDF Knowledge Graph Visualization From a Knowledge Extraction System

In this paper, we present a system to visualize RDF knowledge graphs. These graphs are obtained from a knowledge extraction system designed by GEOLSemantics. This extraction is performed using natural language processing and trigger detection. The user can visualize subgraphs by selecting some ontology features like concepts or individuals. The system is also multilingual, with the use of the annotated ontology in English, French, Arabic and Chinese

Resources Annotation, Retrieval and Presentation: a semantic annotation management system

International audienceThis paper addresses the problem of the management of resources metadata. A variety of responses are discussed, and we describe one possible way forward, which uses a semantic annotation management tool. The term 'semantic' describes the ability to create, retrieve, query and navigate knowledgeably about things identified by a Web URI. The support for this semantic tool is RDF, through the integration of Jena, an open-source RDF API provided by HP laboratory. Thanks to RDF capabilities, this tool offers new search features such as hierarchical browsing based on the structure of RDF vocabularies and faceted-browsing using properties lists defined by the end-user. The navigation inside annotations uses intuitive modes such as left/right and backward/forward movements. Presentation is controlled by the user using a subset of the Fresnel language to specify how RDF graphs are presented. This work is ongoing; certain open issues are raised

Semantic Faceted Search: Safe and Expressive Navigation in RDF Graphs

Faceted search and querying are the two main paradigms to search the Semantic Web. Querying languages, such as SPARQL, oer expressive means for searching knowledge bases, but they are dicult to use. Query assistants help users to write well-formed queries, but they do not prevent empty results. Faceted search supports exploratory search, i.e., guided navigation that returns rich feedbacks to users, and prevents them to make navigation steps that lead to empty results (dead-ends). However, faceted search systems do not oer the same expressiveness as query languages. We introduce semantic faceted search, the combination of an expressive query language and faceted search to reconcile the two paradigms. The query language is basically SPARQL, but with a syntax that extends Turtle with disjunction and negation, and that better ts in a faceted search interface: LISQL. We formalize the navigation of faceted search as a navigation graph, where nodes are queries, and navigation links are query transformations. We prove that this navigation graph is safe (no dead-end), and complete (every query that is not a dead-end can be reached by navigation). That formalization itself is a contribution to faceted search. A prototype, Camelis 2, has been implemented, and a usability evaluation with graduate students demonstrated that semantic faceted search retains the ease-of-use of faceted search, and enables most users to build complex queries with little training