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View article: Minimal Model Reasoning in Description Logics: Don’t Try This at Home!
Minimal Model Reasoning in Description Logics: Don’t Try This at Home! Open
Reasoning with minimal models has always been at the core of many knowledge representation techniques, but we still have only a limited understanding of this problem in Description Logics (DLs). Minimization of some selected predicates---l…
View article: Expressive Description Logics with Rich Yet Affordable Numeric Constraints
Expressive Description Logics with Rich Yet Affordable Numeric Constraints Open
Description Logics (DLs) excel at representing structured knowledge in several application domains, but fall very short when it comes to reasoning about their numeric aspects. We consider the expressive DL ALCHOIQ with closed predicates an…
View article: SHACL Validation in the Presence of Ontologies: Semantics and Rewriting Techniques
SHACL Validation in the Presence of Ontologies: Semantics and Rewriting Techniques Open
SHACL and OWL are two prominent W3C standards for managing RDF data. These languages share many features, but they have one fundamental difference: OWL, designed for inferring facts from incomplete data, makes the open-world assumption, wh…
View article: Common Foundations for SHACL, ShEx, and PG-Schema
Common Foundations for SHACL, ShEx, and PG-Schema Open
Graphs have emerged as an important foundation for a variety of applications, including capturing and reasoning over factual knowledge, semantic data integration, social networks, and providing factual knowledge for machine learning algori…
View article: Stable Model Semantics for Description Logic Terminologies
Stable Model Semantics for Description Logic Terminologies Open
This paper studies a stable model semantics for Description Logic (DL) knowledge bases (KBs) and for (possibly cyclic) terminologies, ultimately showing that terminologies under the proposed semantics can be equipped with effective reasoni…
View article: Datalog rewritability and data complexity of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"> <mml:mi mathvariant="script">ALCHOIQ</mml:mi> </mml:math> with closed predicates
Datalog rewritability and data complexity of with closed predicates Open
We study the relative expressiveness of ontology-mediated queries (OMQs) formulated in the expressive Description Logic ALCHOIQ extended with closed predicates. In particular, we present a polynomial time translation from OMQs into Datalog…
View article: Reconciling SHACL and Ontologies: Semantics and Validation via Rewriting
Reconciling SHACL and Ontologies: Semantics and Validation via Rewriting Open
OWL and SHACL are two prominent W3C standards for managing RDF graphs, the data model of the Web. They are used for different purposes and make different assumptions about the completeness of data: SHACL is used for expressing integrity co…
View article: Description Logics with Pointwise Circumscription
Description Logics with Pointwise Circumscription Open
Circumscription is one of the most powerful ways to extend Description Logics (DLs) with non-monotonic reasoning features, albeit with huge computational costs and undecidability in many cases. In this paper, we introduce pointwise circums…
View article: Dataset used in Evaluation in Paper "Recursive SHACL: A Case for Adopting the Well-founded Semantics"
Dataset used in Evaluation in Paper "Recursive SHACL: A Case for Adopting the Well-founded Semantics" Open
We publish here the subset of the DBPedia dataset that was used to evaluate three SHACL validators. The 'dbpedia.zip' contains the RDF triples that make up the dataset. We used the triplestore Virtuoso, running version 07.20.3236 as the SP…
View article: The biggest business process management problems to solve before we die
The biggest business process management problems to solve before we die Open
View article: Magic shapes for SHACL validation
Magic shapes for SHACL validation Open
A key prerequisite for the successful adoption of the Shapes Constraint Language (SHACL)---the W3C standardized constraint language for RDF graphs---is the availability of automated tools that efficiently validate targeted constraints (kno…
View article: Query Rewriting for Horn-SHIQ Plus Rules
Query Rewriting for Horn-SHIQ Plus Rules Open
Query answering over Description Logic (DL) ontologies has become a vibrant field of research. Efficient realizations often exploit database technology and rewrite a given query to an equivalent SQL or Datalog query over a database associa…
View article: Reasoning about Explanations for Non-validation in SHACL
Reasoning about Explanations for Non-validation in SHACL Open
The Shapes Constraint Language (SHACL) is a recently standardized language for describing and validating constraints over RDF graphs. The SHACL specification describes the so-called validation reports, which are meant to explain to the use…
View article: Bounded Predicates in Description Logics with Counting
Bounded Predicates in Description Logics with Counting Open
Description Logics (DLs) support so-called anonymous objects, which significantly contribute to the expressiveness of these KR languages, but also cause substantial computational challenges. This paper investigates reasoning about upper bo…
View article: Process Mining with Common Sense.
Process Mining with Common Sense. Open
We argue that, with the growth of process mining in breadth (variety of covered tasks) and depth (sophistication of the considered pro- cess models), event logs need to be augmented by commonsense knowl- edge to provide a better input for …
View article: Special Issue on Ontologies and Data Management: Part II
Special Issue on Ontologies and Data Management: Part II Open
View article: Special Issue on Ontologies and Data Management: Part I
Special Issue on Ontologies and Data Management: Part I Open
View article: Ontologies and Data Management: A Brief Survey
Ontologies and Data Management: A Brief Survey Open
Information systems have to deal with an increasing amount of data that is heterogeneous, unstructured, or incomplete. In order to align and complete data, systems may rely on taxonomies and background knowledge that are provided in the fo…
View article: Datalog Rewritability and Data Complexity of ALCHOIF with Closed Predicates
Datalog Rewritability and Data Complexity of ALCHOIF with Closed Predicates Open
We study the relative expressiveness of ontology-mediated queries (OMQs) formulated in the expressive Description Logic ALCHOIF extended with closed predicates. In particular, we present a polynomial-time translation from OMQs into Datalog…
View article: An ExpTime Upper Bound for ALC with Integers
An ExpTime Upper Bound for ALC with Integers Open
Concrete domains, especially those that allow to compare features with numeric values, have long been recognized as a very desirable extension of description logics (DLs), and significant efforts have been invested into adding them to usua…
View article: An ExpTime Upper Bound for $\mathcal{ALC}$ with Integers (Extended Version)
An ExpTime Upper Bound for $\mathcal{ALC}$ with Integers (Extended Version) Open
Concrete domains, especially those that allow to compare features with numeric values, have long been recognized as a very desirable extension of description logics (DLs), and significant efforts have been invested into adding them to usua…
View article: An ExpTime Upper Bound for $\\mathcal{ALC}$ with Integers (Extended\n Version)
An ExpTime Upper Bound for $\\mathcal{ALC}$ with Integers (Extended\n Version) Open
Concrete domains, especially those that allow to compare features with\nnumeric values, have long been recognized as a very desirable extension of\ndescription logics (DLs), and significant efforts have been invested into\nadding them to u…
View article: Stable Model Semantics for Recursive SHACL
Stable Model Semantics for Recursive SHACL Open
SHACL (SHape Constraint Language) is a W3C recommendation for validating graph-based data against a set of constraints (called shapes). Importantly, SHACL allows to define recursive shapes, i.e. a shape may refer to itself, directly of ind…
View article: Query Rewriting for Ontology-Mediated Conditional Answers
Query Rewriting for Ontology-Mediated Conditional Answers Open
Among many solutions for extracting useful answers from incomplete data, ontology-mediated queries (OMQs) use domain knowledge to infer missing facts. We propose an extension of OMQs that allows us to make certain assumptions—for example, …
View article: Resilient Logic Programs: Answer Set Programs Challenged by Ontologies
Resilient Logic Programs: Answer Set Programs Challenged by Ontologies Open
We introduce resilient logic programs (RLPs) that couple a non-monotonic logic program and a first-order (FO) theory or description logic (DL) ontology. Unlike previous hybrid languages, where the interaction between the program and the th…
View article: Polynomial rewritings from expressive Description Logics with closed predicates to variants of Datalog
Polynomial rewritings from expressive Description Logics with closed predicates to variants of Datalog Open
View article: Relaxing and Restraining Queries for OBDA
Relaxing and Restraining Queries for OBDA Open
We advocate the use of ontologies for relaxing and restraining queries, so that they retrieve either more or less answers, enabling the exploration of a given dataset. We propose a set of rewriting rules to relax and restrain conjunctive q…
View article: Ontology Focusing: Knowledge-enriched Databases on Demand
Ontology Focusing: Knowledge-enriched Databases on Demand Open
We propose a novel framework to facilitate the on-demand design of data-centric systems by exploiting domain knowledge from an existing ontology. Its key ingredient is a process that we call focusing, which allows to obtain a schema for a …
View article: The Triguarded Fragment of First-Order Logic
The Triguarded Fragment of First-Order Logic Open
Past research into decidable fragments of first-order logic (FO) has produced two very prominent fragments: the guarded fragment GF, and the two-variable fragment FO2. These fragments are of crucial importance because they provide signific…
View article: Relaxing and Restraining Queries for OBDA
Relaxing and Restraining Queries for OBDA Open
In ontology-based data access (OBDA), ontologies have been successfully employed for querying possibly unstructured and incomplete data. In this paper, we advocate using ontologies not only to formulate queries and compute their answers, b…