Abstract
Knowledge Graphs are increasingly being employed to improve data interoperability, search, and
recommendation, alongside
fostering the adoption of semantic web technologies. The quality of data within these graphs is pivotal, often
validated
against expected data models or shapes to enhance accuracy. Various technologies implement knowledge graphs;
RDF-based
triplestores are canonical in the Semantic Web, while in the graph databases context, Property Graphs are also
considered for Knowledge Graphs. Wikidata, a popular Knowledge Graph, offers RDF through its SPARQL query
service, but
its data model aligns closely with Property Graphs using qualifiers and references, and the recent proposal of
RDF-Star
can bridge the gap between RDF and Property Graphs.
Shape Expressions (ShEx) and Shapes Constraint Language (SHACL) were proposed for RDF validation while in the
case of
Property Graphs, PGSchema was proposed, as well as other proposals like PShEx or ProGS. Wikidata adopted
Entity Schemas,
which are based on ShEx as well as its own property constraint system, and there is a proposal called WShEx.
This tutorial explores different types of Knowledge Graphs and approaches for their validation. We will also
review practical
applications like inferring shapes from existing data and creating conforming subsets of Knowledge Graphs.
Topics
This is a half-day tutorial with the following topics:
- Introduction to Knowledge graphs
- Types of Knowledge Graphs:
- RDF graphs
- Property Graphs
- Wikidata and Wikibase graphs
- RDF-Star (RDF 1.2)
- Shaping RDF:
- Introduction to ShEx
- Introduction to SHACL
- ShEx & SHACL compared
- Shaping other types of Knowledge Graphs
- Shaping Wikidata and Wikibase graphs: Entity Schemas and WShEx
- Shaping property graphs: P-ShEx, PGSchema, etc.
- Shaping RDF-Star: ShEx-Star
- Applications: Inferring shapes from data, Knowledge Graphs Subsets, etc.
We plan to devote the first slot to the first 3 items (knowledge graphs as well as Validating RDF
technologies, ShEx and SHACL) which are more introductory,
and the second slot for the rest of the items, which are more specialised.
Goals
- Attendees will understand the different types of technologies to implement Knowledge Graphs
- Users will understand the differences between the data models of RDF, Property graphs, Wikibase and
RDF-Star.
- Participants will understand use cases for defining shapes and validating Knowledge Graphs.
- Participants will be able to create their own RDF data shapes or Schemas and validate instance data
against them using ShEx and SHACL.
- They will see how RDF validation works in ShEx and SHACL.
- Hands-on experience will leave users comfortable using existing tools to solve practical needs in
communicating
schemas and verifying instance data conformance.
- Users will be able to assess and compare the differences between ShEx, SHACL and other validation
approachs for property graphs and Wikibase.
Tutorial type and intended audience
- Target audience: Anyone interested in Knolwedge Graphs and data quality.
- Tutorial type: We consider that this is a introductory/specialised tutorial as it can serve as an
introduction to
people that are not aware of the technologies, but we can also offer specialised knowledge about validating
property
graphs in the second slot.
- Prior knowledge: Some rudimentary knowledge of RDF and Turtle is expected, although a short introduction to
the
RDF data model will be done.
- Tutorial type: Half day tutorial (14h to 17:40h, 11th November 2024).
- Materials: We will create a github repository containing the running examples that can be executed online
using
the following tools:
Anyone interested in Semantic Web technologies and tools can attend this tutorial.
Some rudimentary knowledge of RDF and Turtle is expected, although a short introduction to the RDF data model
will be done.
Tutoring team
- Jose Emilio Labra Gayo.
Full Professor at University of Oviedo, Spain.
Founder and main researcher of WESO (Web Semantics Oviedo) research group,
which collaborates with different companies around the world applying semantic web technologies.
The development of data portals for several companies and public administrations led to his interest on RDF
validation.
He was a member of the W3C Data Shapes working group and of the W3C community groups:
Shape Expressions and SHACL.
He implemented the SHACL and ShEx library SHaclEX in Scala,
maintains the online RDF validator services RDFShape
and WikiShape, and is now implementing the rudof library in Rust which can also be used to validate RDF
with ShEx, SHACL, DCTAP, etc.
Registration and schedule
To register, visit: ISWC'24
The tutorial will start at 9:00h and has two slots: 9:00h to 10:40h and 11:00h to 11:40h on Monday, 11th
November
2024 (see
Program).