The modular structure of an ontology: an empirical study (WoMO-10) (original) (raw)

The Modular Structure of an Ontology: Atomic Decomposition towards Applications

dcs.bbk.ac.uk

Modularity in ontologies Modern ontologies can get quite large as well as complex, which poses challenges to tools and users when it comes to processing, editing, analyzing them, or reusing their parts. This suggests that exploiting modularity of ontologies might be fruitful, and research into this topic has been an active area for ontology engineering. Much recent effort has gone into developing logically sensible modules, that is, parts of an ontology which offer strong logical guarantees for intuitive modular properties. One such guarantee is called coverage. It means that a module captures all the ontology's knowledge about a given set of terms (signature). A module in this sense is a subset of an ontology's axioms that provides coverage for a signature, and each possible signature determines such a module. The minimal modules to provide coverage for a signature are those based on Conservative Extensions (CEs) , that are however not feasible to be computed for many expressive languages. Modules based on syntactic locality [5] also provide coverage because they are efficiently computable approximations of CEs; however, such modules are not in general minimal.

The Modular Structure of an Ontology: Atomic Decomposition and Module Count

informatik.uni-bremen.de

Extracting a subset of a given ontology that captures all the ontology's knowledge about a specified set of terms is a well-understood task. This task can be based, for instance, on locality-based modules. However, a single module does not allow us to understand neither topicality, connectedness, structure, or superfluous parts of an ontology, nor agreement between actual and intended modeling. The strong logical properties of locality-based modules suggest that the family of all such modules of an ontology can support comprehension of the ontology as a whole. However, extracting that family is not feasible, since the number of locality-based modules of an ontology can be exponential w.r.t. its size. In this paper we report on a new approach that enables us to efficiently extract a polynomial representation of the family of all locality-based modules of an ontology. We also describe the fundamental algorithm to pursue this task, and report on experiments carried out and results obtained.

The Modular Structure of an Ontology: Atomic Decomposition

informatik.uni-bremen.de

Extracting a subset of a given ontology that captures all the ontology's knowledge about a specified set of terms is a well-understood task. This task can be based, for instance, on locality-based modules. However, a single module does not allow us to understand neither topicality, connectedness, structure, or superfluous parts of an ontology, nor agreement between actual and intended modeling. The strong logical properties of locality-based modules suggest that the family of all such modules of an ontology can support comprehension of the ontology as a whole. However, extracting that family is not feasible, since the number of localitybased modules of an ontology can be exponential w.r.t. its size. In this paper we report on a new approach that enables us to efficiently extract a polynomial representation of the family of all locality-based modules of an ontology. We also describe the fundamental algorithm to pursue this task, and report on experiments carried out and results obtained.

T.: The modular structure of an ontology: an empirical study

2012

systems are desirable, all other things being equal. Given a well-designed modular program, it is generally easier to process, modify, and analyze it and to reuse parts by exploiting the modular structure. As a result, support for modules

Extracting modules from ontologies: Theory and practice

2007

The ability to extract meaningful fragments from an ontology is essential for ontology re-use. We propose a definition of a module that guarantees to completely capture the meaning of a given set of terms, i.e., to include all axioms relevant to the meaning of these terms, and study the problem of extracting minimally sized modules. We show that the problem of determining whether a subset of an ontology is a module for a given vocabulary is undecidable even for rather restricted sub-languages of OWL DL. Hence we propose two "approximations", i.e., alternative definitions of modules for a vocabulary that still provide the above guarantee, but that are possibly too strict, and that may thus result in larger modules: the first approximation is semantic and can be checked using existing DL reasoners; the second is syntactic, and can be computed in polynomial time. Finally, we report on an empirical evaluation of our syntactic approximation that demonstrates that the modules we extract are surprisingly small.

Just the right amount: extracting modules from ontologies

2007

Abstract The ability to extract meaningful fragments from an ontology is key for ontology re-use. We propose a definition of a module that guarantees to completely capture the meaning of a given set of terms, ie, to include all axioms relevant to the meaning of these terms, and study the problem of extracting minimal modules. We show that the problem of determining whether a subset of an ontology is a module for a given vocabulary is undecidable even for rather restricted sub-languages of OWL DL.

Extracting modules from ontologies: A logic-based approach

2009

The ability to extract meaningful fragments from an ontology is essential for ontology reuse. We propose a definition of a module that guarantees to completely capture the meaning of a given set of terms, ie, to include all axioms relevant to the meaning of these terms. We show that the problem of determining whether a subset of an ontology is a module for a given vocabulary is undecidable even for OWL DL. Given these negative results, we propose sufficient conditions for a for a fragment of an ontology to be a module.

Zooming in on Ontologies: Minimal Modules and Best Excerpts

2017

Ensuring access to the most relevant knowledge contained in large ontologies has been identified as an important challenge. To this end, minimal modules (sub-ontologies that preserve all entailments over a given vocabulary) and excerpts (certain, small number of axioms that best capture the knowledge regarding the vocabulary by allowing for a degree of semantic loss) have been proposed. In this paper, we introduce the notion of subsumption justification as an extension of justification (a minimal set of axioms needed to preserve a logical consequence) to capture the subsumption knowledge between a term and all other terms in the vocabulary. We present algorithms for computing subsumption justifications based on a simulation notion developed for the problem of deciding the logical difference between ontologies. We show how subsumption justifications can be used to obtain minimal modules and to compute best excerpts by additionally employing a partial Max-SAT solver. This yields two s...