Abstract
Knowledge Graphs (KGs) are a key technology for realizing the Semantic Web vision. While RDF-based
triplestores have
traditionally been the foundation of Semantic Web applications, Property Graphs are also widely used in graph
databases.
Wikidata exemplifies the convergence of these approaches:
although it provides RDF data through SPARQL, its model
incorporates Property Graph-like features such as qualifiers and references.
The introduction of
RDF 1.2 further narrows this gap
by enabling statements about statements.
Ensuring data quality in KGs requires validating data against predefined schemas or shapes.
In the RDF ecosystem, ShEx and
SHACL have been proposed for describing and validating data. More
recently,
SHACL 1.2 is under
development, adding new expressive capabilities and alignment with RDF 1.2.
For Property Graphs, schema and validation proposals such as PGSchema, PShEx, and ProGS have emerged, while
GQL
introduces support for typed graphs. Wikidata complements its property constraint system with Entity Schemas
based on
ShEx, and related proposals such as WShEx have also been explored.
This tutorial surveys major approaches for describing and validating RDF and Property Graph-based Knowledge
Graphs, with
particular attention to SHACL 1.2 and recent efforts to bridge RDF and Property Graph technologies.
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 1.2
- Shaping RDF:
- Introduction to ShEx
- Introduction to SHACL
- ShEx & SHACL compared
- Recent advances in ShEx and SHACL (SHACL 1.2)
- Shaping other types of Knowledge Graphs
- Shaping Wikidata and Wikibase graphs: Entity Schemas and WShEx
- Shaping property graphs: P-ShEx, PGSchema, etc.
- Shaping RDF-1.2: SHACL 1.2 & 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
After attending this tutorial, participants will be able to:
- Distinguish between the main technologies and data models used to implement Knowledge Graphs, including
RDF, RDF~1.2,
Property Graphs, and Wikibase.
- Explain the role of schemas and shapes in ensuring Knowledge Graph quality and interoperability.
- Identify use cases for describing and validating Knowledge Graph data.
- Create and use schemas for RDF data using Shape Expressions (ShEx) and SHACL.
- Validate RDF data against ShEx and SHACL schemas and interpret validation results.
- Compare the capabilities, strengths, and limitations of ShEx, SHACL, and emerging validation approaches
for Property
Graphs and Wikibase.
Tutorial type and intended audience
- Target audience: Researchers, practitioners, and students interested in Knowledge Graphs, data
quality, schema languages, and graph
validation technologies. The tutorial is particularly relevant for those working with RDF, Wikidata/Wikibase,
Property
Graphs, or graph database technologies.
- Tutorial type: The tutorial combines introductory and specialized content. It provides an overview of
Knowledge Graph technologies and
data models for newcomers, while offering an in-depth treatment of schema definition and validation techniques
for RDF,
Wikibase, and Property Graphs.
- Level: Beginner to intermediate. No prior experience with schema languages is required, although the
material will also be
valuable to attendees with existing Knowledge Graph expertise.
- Prerequisites: Basic familiarity with RDF and Turtle is recommended. A brief introduction to the RDF
data model will be included to
ensure a common starting point for all participants.
- Tutorial format: Half-day tutorial combining lectures, demonstrations, and hands-on exercises.
- Materials: We will create a github repository containing the running examples that can be executed online
using
the following tools:
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 maintains the library rudof in Rust
and implemented the ShEx and SHACL library SHaclEX in Scala,
maintains the online RDF validator services RDFShape
and WikiShape.
Examples
Examples and other material will be available at