Motivation Data on the Web

Some eyecatching opener illustrating growth and or diversity of web data

Profiling & Exploration of Linked Datasets

Stefan Dietze, Besnik Fetahu, Davide Taibi L3S Research Center, DE,

@stefandietze, http://purl.org/dietze

Stefan Dietze 12/03/14

Data curation and dataset profiling

LinkedUp

Dataset Catalog

Stefan Dietze 12/03/14

Catalog of data (LinkedUp Catalog): classification of datasets according to resource types, disciplines/topics, data quality, accessability, etc

Infrastructure for distributed/federated querying

describes

Which datasets are useful & trustworthy for case XY (eg „learning about the solar system“) ?

Which topics (eg „Astronomy“) are covered by dataset X?

Which datasets offer videos (slides, publications, statistics etc)?

LinkedUp Data Catalog in a nutshell

http://datahub.io/group/linked-education

http://data.linkededucation.org/linkedup/catalog/

RDF (VoID) dataset catalog: browse & query distributed datasets

Live information about endpoint accessibility

Federated queries using type mappings

Stefan Dietze 12/03/14

db:Astro. Objects

Extracting Topic Profiles of Linked Datasets

Dataset Metadata

Stefan Dietze 12/03/14

Schema mappings

BIBO

AAISO

FOAF

contains

Entity disambiguation

Topic profile extraction

db:Astronomy

db:Astro. Objects

LinkedUp

Dataset Catalog

yov:Video

po:Programme

BBC Programme

<po:Programme …>

<po:Series>Wonders of the Solar System</.>

<po:Actor>Brian Cox</…>

</po:Programme…>

<yo:Video …>

<dc:title>Pluto & the

Dwarf Planets</dc:title>

…

</yo:Video…>

Yovisto Video

bibo:Fil bibo:Fi

bibo:Film

What’s all the data about: exploring topics of LOD in a nutshell http://data-observatory.org/lod-profiles/

Stefan Dietze 12/03/14

Visualisation & exploration of dataset-topic-graph (datasets, topics, relationships)

Includes all responsive datasets of LOD Cloud

A Scalable Approach for Efficiently Generating Structured Dataset Topic Profiles, Fetahu, B., Dietze, S., Nunes, B.P., Cassanova M., Nejdl, W. (2014), 11th Extended Semantic Web Conference, ESWC2014, Greece, May 2014.

Stefan Dietze 12/03/14

dbp:Category:Royal_Medal_winners

dbp:Category:1955_births dbp:Category:People_from_London

dbp:Category:Buzzwords

dbp:Category:Web_Services

dbp:Category:HTTP

dbp:Category:Unitarian_Universalists

dbp:Category:World_Wide_Web

What have these categories in common?

Stefan Dietze 12/03/14

Diversity of category profile for a single paper

Berners-Lee, Tim; Hendler, James, Ora Lassila (2001). "The Semantic Web". Scientific American Magazine.

person

document

dbp:Tim_Berners-Lee

dbp:Category:1955_births dbp:Category:People_from_London

dbp:Category:Buzzwords

dbp:Semantic_Web

dbp:Category:Semantic_Web

dbp:Category:Web_Services

dbp:Category:HTTP

dbp:Category:Unitarian_Universalists

first-level categories (dcterms:subject)

dbp:Category:World_Wide_Web

dbp:Category:Royal_Medal_winners

DBpedia category graph not an ideal “topic” vocabulary:

Broad and noisy

“Categories” vs “topics” (for capturing disciplines, thesauri like UNESCO Thesaurus seem better suited)

Lack of clear hierarchy: graph, not a tree

Mixing categories across resource types (document, person etc) creates “perceived noise”

But: broadness is useful as general vocabulary for categorisation of all sorts of resource types

Stefan Dietze 12/03/14

Dataset profiling: some lessons learned

Stefan Dietze 12/03/14

http://data-observatory.org/led-explorer/

Type specific views on datasets/ categories (ie “topics”)

“Document” (foaf:document)

“Person “ (foaf:person)

“Course” (aaiso:course)

Currently applied to datasets in LinkedUp Catalog only (as schema mappings already available here)

More precise profiles of educational datasets

Thank you!

12/03/14 10 Stefan Dietze

http://data-observatory.org/led-explorer/

http://data-observatory.org/lod-profiles/