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Europeana Semantic Layer

EuropeanaConnect significantly improves the possibility for Europeana users to discover the online collections of European museums, archives, libraries and audio-visual institutions by semantically enriching metadata. Thereby Europeana will be able to automatically suggest materials to the user that are related to a particular retrieved object. EuropeanaConnect also contributes to the Europeana Data Model (EDM). The following results and activities have been carried out so far:

Semantic Layer

The Semantic Layer built by EuropeanaConnect aims at providing a uniform, machine-actionable, web-enabled access to the reference knowledge capitalized by the various stakeholders of The objective is to make the metadata knowledge available for enabling the users to benefit from semantics-intensive functions, as will be specified in other WP1 deliverables.

Europeana Data Model

To enable semantic search a common data model was needed. WP1 contributed to create the Europeana Data Model (EDM). The EDM is aimed at being an integration medium for collecting, connecting and enriching the descriptions/metadata provided by Europeana content providers. As such, it includes any element (i.e., class or property) found in a content provider's description/metadata. Giving an account of all these elements is clearly an impossible task, since they form an open set, i.e. a set that can be extended as new providers join the Europeana information space. In the course of converting ESE (Europeana Semantic Elements) to the EDM, it was decided to make this data available in the Linked Open Data Cloud. WP1 contributed in terms of technical and lobbying support.
Europeana Data Model
Europeana LOD Pilot - Download
Europeana Linked Open Data

Community Meetings to approve EDMv5 were held:

Semantic Search Engine for Europeana in the Thought lab pilot:

The links between metadata records and structured vocabularies in the Semantic Layer can be exploited for semantic search. In semantic search, a machine uses these links to make associations and put search terms into context. For example, a search for 'Picasso' will lead to works created by Pablo Picasso as well as works depicting the painter. Artworks made of 'Picasso marble' are also retrieved and each of these contexts can be displayed in a separate cluster. Through the use of multilingual vocabularies, limited multilinguality is achieved. In this WIKI we track the vocabulary contributions:

The semantic search engine prototype is available in English, French and Dutch and contains data of the Rijksmuseum Amsterdam, the Musée du Louvre in Paris, and the Rijksbureau voor Kunsthistorische Documentatie (Netherlands Institute for Art History) in The Hague.

visit the Semantic Searching Prototype here:

Semantic Alignments

To achieve the interconnectedness of Europeana resources, we need to establish links between the vocabularies that are used to annotate these resources. Rather than attempting to produce one unified ontology, our approach is to find alignments between the local vocabularies used to annotate the original data and more general pivot vocabularies.

AMALGAME Matching Tool
Amalgame (AMsterdam ALignment GenerAtion MEtatool) is a tool for finding, evaluating and managing vocabulary alignments. Its goal is to seek to combine existing matching techniques and methods such as those developed within the context of the Ontology Alignment Evaluation Initiative (OAEI), in which different alignment methods can be combined using a workflow setup. Amalgame features a workflow composition tool, where a user can iteratively select mapping components, filters or selection actions on vocabularies or intermediate mapping results. By concatenating these actions, an alignment workflow emerges. The (intermediary) alignment results can be inspected and evaluated through the extensive statistics and evaluation facilities. More information can be found at the Amalgame weblog:

Fuzzy Alignment Tool
The Fuzzy Alignment Tool is used for computing the strength of each alignment. It implements a string-distance metric that uses substring commonalities and differences of the compared entities, thus producing strengths that are more realistic. The alignment strength is a value between 0 and 1.

DSNotify is a generic change detection framework for linked sources that informs data-consuming actors about the various types of events (create, remove, move, update) that can occur in data sources due to link integrity errors. Link integrity errors (i.e., broken links) occur when resources referenced by a link cannot be accessed. Reasons for broken links include removed, moved or renamed resources, network problems or unplugged devices. More information can be found at the DSNotify website:

Semantic Enrichment and Enrichment Experiments

While for many Europeana metadata records terms from structured vocabularies are already used, a large number of metadata fields are filled with unstructured textual content. To further integrate these metadate records in the semantic layer, enrichment is needed to establish explicit semantic links between the representation of the collection objects (surrogates) and the (Europeana) vocabularies.
In our approach, we employ the Amalgame tool to enrich these values by mapping them to existing vocabularies. In a first step, the values for a given metadata field are converted to a temporary vocabulary, which is then interactively aligned with the target vocabulary. The resulting correspondences are then stored in the semantic layer as metadata for a separate Europeana-owned aggregation, to preserve provenance data.

RDF-based Metadata Management

Organizations often have difficulties to decide which solution they should adopt because comprehensive comparisons of existing RDF stores are hardly available and experiences w.r.t performance and scalability are still missing. This report summarizes the results of qualitative and quantitative study carried out on existing RDF stores in the context of the European Digital Library project.
Europeana RDF Store Report

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