Tobias Käfer

dblp:121/4546 · also Tobias Christof Käfer · DBLP profile ↗
← Back
12ranked-venue papers in the field
3as first author
8since 2021 · last 2026
0000-0003-0576-7457ORCID · verified

Domains — venue-derived; a paper can count in several

Knowledge Engineering, Semantic Web & Information Systems · 7 (3 first)Information Retrieval & Web Search · 5
YearPublicationVenuePosition
2026 Proving Soundness of SPARQL Query Results Using Selective Disclosure of RDF Datasets and Zero-Knowledge Proofs
Christoph Braun 0002, Jesse Wright, Tobias Käfer
ESWC (1)3
2026 BOLD: A Simulation Framework for Dynamic Linked Data Environments and a Benchmark for Linked Data User Agents
Tobias Käfer, Victor Charpenay, Andreas Harth
ESWC (2)1
2025 Real-E: A Foundation Benchmark for Advancing Robust and Generalizable Electricity Forecasting
abstract
Energy forecasting is vital for grid reliability and operational efficiency. Although recent advances in time series forecasting have led to progress, existing benchmarks remain limited in spatial and temporal scope and lack multi-energy features. This raises concerns about their reliability and applicability in real-world deployment. To address this, we present the Real-E dataset, covering over 74 power stations across 30+ European countries over a 10-year span with rich metadata. Using Real- E, we conduct an extensive data analysis and benchmark over 20 baselines across various model types. We introduce a new metric to quantify shifts in correlation structures and show that existing methods struggle on our dataset, which exhibits more complex and non-stationary correlation dynamics. Our findings highlight key limitations of current methods and offer a strong empirical basis for building more robust forecasting models
Chen Shao, Michael Färber 0001, Sebastian Pütz, Benjamin Schäfer 0001, Tobias Käfer, Zhanbo Huang, Zhenyi Zhu
CIKM6
2025 RDF-Based Semantics for Selective Disclosure and Zero-Knowledge Proofs on Verifiable Credentials
Christoph Braun 0002, Tobias Käfer
ESWC (1)2
2024 AuthApp - Portable, Reusable Solid App for GDPR-Compliant Access Granting
Andreas Both 0001, Thorsten Kastner, Dustin Yeboah, Christoph Braun 0002, Daniel Schraudner, Sebastian Schmid 0001, Tobias Käfer, Andreas Harth
ICWE7
2024 SSI, from Specifications to Protocol? Formally Verify Security!
abstract
We evaluate a bundle of specifications from the Self-Sovereign Identity (SSI) paradigm to construct an authentication protocol for the Web. We demonstrate how relevant standards such as W3C Verifiable Credentials (VC), W3C Decentralised Identifiers (DIDs), and components of the Hyperledger Aries Framework are to be assembled methodologically into a protocol. We make those assumptions from standard trust models explicit that underlie the derived protocol, and verify security and privacy properties, notably secrecy, authentication, and unlinkability. This enables us to formally justify the additional precision that we urge these specifications to consider, to ensure that implementors of SSI-based systems do not neglect security-critical controls.
Christoph Braun 0002, Ross Horne, Tobias Käfer, Sjouke Mauw
WWW3
2023 SISSI: An Architecture for Semantic Interoperable Self-Sovereign Identity-based Access Control on the Web
abstract
We present an architecture for authentication and authorization on the Web that is based on the Self-Sovereign Identity paradigm. Using our architecture, we aim to achieve semantic interoperability across different approaches to SSI. We build on the underlying RDF data model of the W3C’s recommendation for Verifiable Credentials and specify semantic access control rules using SHACL. Our communication protocol for an authorization process is based on Decentralised Identifiers and extends the Hyperledger Aries Present Proof protocol. We propose a modular architecture that allows for flexible extension, e. g., for supporting more signature schemes or Decentralised Identifier Methods. For evaluation, we implemented a Proof-of-Concept: We show that a Web-based approach to SSI outperfoms a blockchain-based approach to SSI in terms of End-to-End execution time.
Christoph Braun 0002, Vasil Papanchev, Tobias Käfer
WWW3
2022 Web Push Notifications from Solid Pods
Christoph Braun 0002, Tobias Käfer
ICWE2
2019 BTC-2019: The 2019 Billion Triple Challenge Dataset
José-Miguel Herrera, Aidan Hogan, Tobias Käfer
ISWC (2)3
2018 Specifying, Monitoring, and Executing Workflows in Linked Data Environments
abstract
We present an ontology for representing workflows over components with Read-Write Linked Data interfaces and give an operational semantics to the ontology via a rule language. Workflow languages have been successfully applied for modelling behaviour in enterprise information systems, in which the data is often managed in a relational database. Linked Data interfaces have been widely deployed on the web to support data integration in very diverse domains, increasingly also in scenarios involving the Internet of Things, in which application behaviour is often specified using imperative programming languages. With our work we aim to combine workflow languages, which allow for the high-level specification of application behaviour by non-expert users, with Linked Data, which allows for decentralised data publication and integrated data access. We show that our ontology is expressive enough to cover the basic workflow patterns and demonstrate the applicability of our approach with a prototype system that observes pilots carrying out tasks in a mixed-reality aircraft cockpit. On a synthetic benchmark from the building automation domain, the runtime scales linearly with the size of the number of Internet of Things devices.
Tobias Käfer, Andreas Harth
ISWC (1)1
2014 The Role of Ontology Engineering in Linked Data Publishing and Management: An Empirical Study
abstract
In this article the authors evaluate the adoption and applicability of established ontology engineering results by the Linked Data providers' community. The evaluation relies on a combination of qualitative and quantitative methods; in particular, the authors conducted an analytical survey containing structured interviews with data publishers in order to give an account of the current ontology engineering practice in Linked Data provisioning, and compared and expanded our findings with statistics on ontology development and usage provided by the Billion Triple Challenges datasets from 2012 (using the vocab.cc platform) and from 2014 and other related tools. The findings of the evaluation allow data practitioners and ontologists to yield a better understanding of the conceptual part of the LOD Cloud; and form the basis for the definition of purposeful, empirically grounded guidelines and best practices for developing, managing and using ontologies in the new application scenarios that arise in the context of Linked Data.
Markus Luczak-Rösch, Elena Simperl, Steffen Stadtmüller, Tobias Käfer
Int. J. Semantic Web Inf. Syst.4
2013 Observing Linked Data Dynamics
Tobias Käfer, Ahmed Abdelrahman, Jürgen Umbrich, Patrick O'Byrne, Aidan Hogan
ESWC1