Research Publications

2012

Booth R, Meyer T, Sombattheera C. A General Family of Preferential Belief Removal Operators. Journal of Philosophical Logic. 2012;41(4). http://www.springerlink.com/content/f6368324072g3344/.

Most belief change operators in the AGM tradition assume an underlying plausibility ordering over the possible worlds which is transitive and complete. A unifying structure for these operators, based on supplementing the plausibility ordering with a second, guiding, relation over the worlds was presented in Booth et al. (Artif Intell 174:1339–1368, 2010). However it is not always reasonable to assume completeness of the underlying ordering. In this paper we generalise the structure of Booth et al. (Artif Intell 174:1339–1368, 2010) to allow incomparabilities between worlds. We axiomatise the resulting class of belief removal functions, and show that it includes an important family of removal functions based on finite prioritised belief bases.

@article{35,
  author = {Richard Booth and Thomas Meyer and C. Sombattheera},
  title = {A General Family of Preferential Belief Removal Operators},
  abstract = {Most belief change operators in the AGM tradition assume an underlying plausibility ordering over the possible worlds which is transitive and complete. A unifying structure for these operators, based on supplementing the plausibility ordering with a second, guiding, relation over the worlds was presented in Booth et al. (Artif Intell 174:1339–1368, 2010). However it is not always reasonable to assume completeness of the underlying ordering. In this paper we generalise the structure of Booth et al. (Artif Intell 174:1339–1368, 2010) to allow incomparabilities between worlds. We axiomatise the resulting class of belief removal functions, and show that it includes an important family of removal functions based on finite prioritised belief bases.},
  year = {2012},
  journal = {Journal of Philosophical Logic},
  volume = {41},
  pages = {711-733},
  issue = {4},
  url = {http://www.springerlink.com/content/f6368324072g3344/},
}
Rens G, Lakemeyer G, Meyer T. A Logic for Specifying Agent Actions and Observations with Probability. In: Kersting, K., Toussaint, M. (Eds.), Sixth Starting AI Researchers' Symposium (STAIRS 2012), Frontiers in Artificial Intelligence and Applications, Vol. 241. ; 2012.

We propose a non-standard modal logic for specifying agent domains where the agent’s actuators and sensors are noisy, causing uncertainty in action and perception. The logic is multi-modal, indexed with actions; the logic is also augmented with observation objects to facilitate knowledge engineers dealing with explicit observations in the environment, and it includes a notion of probability. A tableau method is provided for proving decidability of the proposed logic. It is our conjecture that the tableau rules are complete with respect to the semantics. The proof does not yet exist, however, we discuss the current approach of the proof and provide some examples to motivate our conjecture.

@{34,
  author = {Gavin Rens and G. Lakemeyer and Thomas Meyer},
  title = {A Logic for Specifying Agent Actions and Observations with Probability},
  abstract = {We propose a non-standard modal logic for specifying agent domains where the agent’s actuators and sensors are noisy, causing uncertainty in action and perception. The logic is multi-modal, indexed with actions; the logic is also augmented with observation objects to facilitate knowledge engineers dealing with explicit observations in the environment, and it includes a notion of probability. A tableau method is provided for proving decidability of the proposed logic. It is our conjecture that the tableau rules are complete with respect to the semantics. The proof does not yet exist, however, we discuss the current approach of the proof and provide some examples to motivate our conjecture.},
  year = {2012},
  journal = {Kersting, K., Toussaint, M. (Eds.), Sixth Starting AI Researchers' Symposium (STAIRS 2012), Frontiers in Artificial Intelligence and Applications, Vol. 241},
  pages = {252-263},
}
Britz K, Varzinczak I. Defeasible Modes of Inference: A Preferential Perspective. 2012. http://www.dbai.tuwien.ac.at/NMR12/proceedings.html.

No Abstract

@misc{31,
  author = {Katarina Britz and Ivan Varzinczak},
  title = {Defeasible Modes of Inference: A Preferential Perspective},
  abstract = {No Abstract},
  year = {2012},
  url = {http://www.dbai.tuwien.ac.at/NMR12/proceedings.html},
}
Varzinczak I. Preferential Reasoning: Beyond Propositional Logic and Argument Forms. 2012.

No Abstract

@misc{22,
  author = {Ivan Varzinczak},
  title = {Preferential Reasoning: Beyond Propositional Logic and Argument Forms},
  abstract = {No Abstract},
  year = {2012},
}
Booth R, Meyer T, Varzinczak I. PTL: A Propositional Typicality Logic. In: Proceedings of the 13th European Conference on Logics in Artificial Intelligence (JELIA). ; 2012.

We introduce Propositional Typicality Logic (PTL), a logic for reasoning about typicality. We do so by enriching classical propositional logic with a typicality operator of which the intuition is to capture the most typical (or normal) situations in which a formula holds. The semantics is in terms of ranked models as studied in KLM-style preferential reasoning. This allows us to show that rational consequence relations can be embedded in our logic. Moreover we show that we can define consequence relations on the language of PTL itself, thereby moving beyond the propositional setting. Building on the existing link between propositional rational consequence and belief revision, we show that the same correspondence holds for rational consequence and belief revision on PTL. We investigate entailment for PTL, and propose two appropriate notions thereof.

@{21,
  author = {Richard Booth and Thomas Meyer and Ivan Varzinczak},
  title = {PTL: A Propositional Typicality Logic},
  abstract = {We introduce Propositional Typicality Logic (PTL), a logic for reasoning about typicality. We do so by enriching classical propositional logic with a typicality operator of which the intuition is to capture the most typical (or normal) situations in which a formula holds. The semantics is in terms of ranked models as studied in KLM-style preferential reasoning. This allows us to show that rational consequence relations can be embedded in our logic. Moreover we show that we can define consequence relations on the language of PTL itself, thereby moving beyond the propositional setting. Building on the existing link between propositional rational consequence and belief revision, we show that the same correspondence holds for rational consequence and belief revision on PTL. We investigate entailment for PTL, and propose two appropriate notions thereof.},
  year = {2012},
  journal = {Proceedings of the 13th European Conference on Logics in Artificial Intelligence (JELIA)},
  pages = {107-119},
}
Moodley K, Meyer T, Varzinczak I. A Protege Plug-in for Defeasible Reasoning. 2012. http://ceur-ws.org/Vol-846/.

We discuss two approaches for defeasible reasoning in Description Logics that allow for the statement of defeasible subsumptions of the form "α subsumed by β usually holds". These approaches are known as prototypical reasoning and presumptive reasoning and are both rooted in the notion of Rational Closure developed by Lehmann and Magidor for the propositional case. Here we recast their definitions in a defeasible DL context and define algorithms for prototypical and presumptive reasoning in defeasible DL knowledge bases. In particular, we present a plug-in for the Protégé ontology editor which imple-ments these algorithms for OWL ontologies. The plug-in is called RaMP and allows the modeller to indicate defeasible information in OWL ontologies and check entailment of defeasible subsumptions from defeasible knowledge bases.

@misc{20,
  author = {Kody Moodley and Thomas Meyer and Ivan Varzinczak},
  title = {A Protege Plug-in for Defeasible Reasoning},
  abstract = {We discuss two approaches for defeasible reasoning in Description Logics that allow for the statement of defeasible subsumptions of the form "α subsumed by β usually holds". These approaches are known as prototypical reasoning and presumptive reasoning and are both rooted in the notion of Rational Closure developed by Lehmann and Magidor for the propositional case. Here we recast their definitions in a defeasible DL context and define algorithms for prototypical and presumptive reasoning in defeasible DL knowledge bases. In particular, we present a plug-in for the Protégé ontology editor which imple-ments these algorithms for OWL ontologies. The plug-in is called RaMP and allows the modeller to indicate defeasible information in OWL ontologies and check entailment of defeasible subsumptions from defeasible knowledge bases.},
  year = {2012},
  url = {http://ceur-ws.org/Vol-846/},
}
Khan ZC, Keet M. ONSET: Automated foundational ontology selection and explanantion. 2012.

No Abstract

@misc{19,
  author = {Zubeida Khan and Maria Keet},
  title = {ONSET: Automated foundational ontology selection and explanantion},
  abstract = {No Abstract},
  year = {2012},
}
Kinyondo J, van Biljon J, Gerber A. The potential role of open source software in overcoming digital poverty. In: 6th IDIA Conference: Alleviating Digital Poverty with ICT innovation in emerging economies - Will ICT Rights make a difference?. ; 2012.

2012: Kinyondo, Josephat; van Biljon, Judy; Gerber, Aurona, 2012.The potential role of open source software in overcoming digital poverty, Alleviating Digital Poverty with ICT innovation in emerging economies. Will ICT Rights make a difference? IDIA2012 Conference Proceedings. 6th IDIA Conference. Steyn J, Kirlidog M. (eds). Beykent University, Istanbul, Turkey. 6-8 September. Pages 122-139. ISBN: 978-975-6319-17-8

@{18,
  author = {Josephat Kinyondo and Judy van Biljon and Aurona Gerber},
  title = {The potential role of open source software in overcoming digital poverty},
  abstract = {2012: Kinyondo, Josephat; van Biljon, Judy; Gerber, Aurona, 2012.The potential role of open source software in overcoming digital poverty,  Alleviating Digital Poverty with ICT innovation in emerging economies. Will ICT Rights make a difference? IDIA2012 Conference Proceedings. 6th IDIA Conference. Steyn J, Kirlidog M. (eds). Beykent University, Istanbul, Turkey. 6-8 September. Pages 122-139.  ISBN: 978-975-6319-17-8},
  year = {2012},
  journal = {6th IDIA Conference: Alleviating Digital Poverty with ICT innovation in emerging economies - Will ICT Rights make a difference?},
}
Moodley D, Pillay A, Seebregts C. Position Paper: Researching and Developing Open Architectures for National Health Information Systems in Developing African Countries. In: Foundations of Health Informatics Engineering and Systems, Revised and Selected Papers, Lecture Notes in Computer Science Volume 7151. Springer; 2012. http://link.springer.com/chapter/10.1007/978-3-642-32355-3_8.

Most African countries have limited health information systems infrastructure. Some health information system components are implemented but often on an adhoc, piecemeal basis, by foreign software developers and designed to solve specific problems. Little attention is usually paid to how these components can fit into an integrated national health information system and interoperate with other components. The Health Enterprise Architecture Laboratory was recently established in the School of Computer Science at the University of KwaZulu-Natal in South Africa to undertake research and build capacity in open health architectures for developing African countries. Based on field experiences and requirements in South Africa, Mozambique and Rwanda, the laboratory is evolving a generic Health Enterprise Architecture Framework and Repository of Tools specifically for low resource settings. In this paper we describe these three initiatives and the expected impact on implementing health information systems in developing African countries.

@inbook{16,
  author = {Deshen Moodley and Anban Pillay and Chris Seebregts},
  title = {Position Paper: Researching and Developing Open Architectures for National Health Information Systems in Developing African Countries},
  abstract = {Most African countries have limited health information systems infrastructure. Some health information system components are implemented but often on an adhoc, piecemeal basis, by foreign software developers and designed to solve specific problems. Little attention is usually paid to how these components can fit into an integrated national health information system and interoperate with other components. The Health Enterprise Architecture Laboratory was recently established in the School of Computer Science at the University of KwaZulu-Natal in South Africa to undertake research and build capacity in open health architectures for developing African countries. Based on field experiences and requirements in South Africa, Mozambique and Rwanda, the laboratory is evolving a generic Health Enterprise Architecture Framework and Repository of Tools specifically for low resource settings. In this paper we describe these three initiatives and the expected impact on implementing health information systems in developing African countries.},
  year = {2012},
  journal = {Foundations of Health Informatics Engineering and Systems, Revised and Selected Papers, Lecture Notes in Computer Science Volume 7151},
  pages = {129-139},
  publisher = {Springer},
  url = {http://link.springer.com/chapter/10.1007/978-3-642-32355-3_8},
}
Naidoo R, Gerber A, van der Merwe A. An Exploratory Survey of Design Science Research among South African Computing Scholars. In: South African Institute for Computer Scientists and Information Technologists: SAICSIT 2012, Centurion, Tshwane. October 1-3. ; 2012.

The debate ensues as to whether the traditional focus of computing research on theory development and verification and therefore has adequate immediate practical relevance. Despite increasing claims of the potential of design science research (DSR) to enhance the utility of the IT artifact and consequently practical relevance of research, many computing researchers seem to be reticent to accept this paradigm as a legitimate form of scholarly research. DSR is a relatively new paradigm in computing and little is known about its uptake in South Africa. In this paper, we investigate the opinions about DSR among South African computing scholars. Findings from a survey of 53 respondents indicate low adoption rates. The paper also investigates some of the key barriers preventing the uptake of DSR. The paper concludes with some implications as well as suggestions for building a local DSR community.

@{13,
  author = {Rennie Naidoo and Aurona Gerber and Alta van der Merwe},
  title = {An Exploratory Survey of Design Science Research among South African Computing Scholars},
  abstract = {The debate ensues as to whether the traditional focus of
computing research on theory development and verification and
therefore has adequate immediate practical relevance. Despite
increasing claims of the potential of design science research
(DSR) to enhance the utility of the IT artifact and consequently
practical relevance of research, many computing researchers seem
to be reticent to accept this paradigm as a legitimate form of
scholarly research. DSR is a relatively new paradigm in
computing and little is known about its uptake in South Africa. In
this paper, we investigate the opinions about DSR among South
African computing scholars. Findings from a survey of 53
respondents indicate low adoption rates. The paper also
investigates some of the key barriers preventing the uptake of
DSR. The paper concludes with some implications as well as
suggestions for building a local DSR community.},
  year = {2012},
  journal = {South African Institute for Computer Scientists and Information Technologists: SAICSIT 2012, Centurion, Tshwane. October 1-3.},
}
Kinyondo J, van Biljon J, Gerber A. An Assessment of Open Source Promotion in addressing ICT Acceptance Challenges in Tanzania. In: IST Africa 2012. ; 2012.

IST-Africa 2012 Conference Proceedings Paul Cunningham and Miriam Cunningham (Eds) IIMC International Information Management Corporation, 2012 ISBN: 978-1-905824-34-2

@{12,
  author = {Josephat Kinyondo and Judy van Biljon and Aurona Gerber},
  title = {An Assessment of Open Source Promotion in addressing ICT Acceptance Challenges in Tanzania},
  abstract = {IST-Africa 2012 Conference Proceedings
Paul Cunningham and Miriam Cunningham (Eds)
IIMC International Information Management Corporation, 2012
ISBN: 978-1-905824-34-2},
  year = {2012},
  journal = {IST Africa 2012},
}
Gerber A, Sinha S, van der Merwe A, Kam M. Accreditation of Academic Programmes in Computing in South Africa. In: 4th Software Engineering Colloquium (SE 2012). ; 2012.

http://www.sosa.org.za/sites/default/files/IEEE_BITF_SE12_Omnibus_Proceedings.pdf

@{11,
  author = {Aurona Gerber and Saurabh Sinha and Alta van der Merwe and Moshe Kam},
  title = {Accreditation of Academic Programmes in Computing in South Africa},
  abstract = {http://www.sosa.org.za/sites/default/files/IEEE_BITF_SE12_Omnibus_Proceedings.pdf},
  year = {2012},
  journal = {4th Software Engineering Colloquium (SE 2012)},
}
Crichton R, Moodley D, Pillay A, Gakuba R, Seebregts C. An Interoperability Architecture for the Health Information Exchange in Rwanda. In: ; 2012.

Rwanda, one of the smallest and most densely populated countries in Africa, has made rapid and substantial progress towards designing and deploying a national health information system. One of the challenging aspects of the system is the design of an architecture to support: interoperability between existing health information systems already in use in the country; incremental extension into a full integrated national health information system without substantial reengineering;and scaling, from a single district in the initial phase, to national level without requiring a fundamental change in technology or design paradigm. This paper describes the key requirements and the design of the current architecture using ISO/IEC/IEEE 42010 standard architecture descriptions. The architecture is based on the Enterprise Service Bus architectural model. We also describe a partial implementation of the architecture, and give a preliminary analysis based on our experiences.

@{10,
  author = {Ryan Crichton and Deshen Moodley and Anban Pillay and R. Gakuba and Chris Seebregts},
  title = {An Interoperability Architecture for the Health Information Exchange in Rwanda},
  abstract = {Rwanda, one of the smallest and most densely populated countries in Africa, has made rapid and substantial progress towards designing and deploying a national health information system. One of the challenging aspects of the system is the design of an architecture to support: interoperability between existing health information systems already in use in the country; incremental extension into a full integrated national health information system without substantial reengineering;and scaling, from a single district in the initial phase, to national level without requiring a fundamental change in technology or design paradigm. This paper describes the key requirements and the design of the current architecture using ISO/IEC/IEEE 42010 standard architecture descriptions. The architecture is based on the Enterprise Service Bus architectural model. We also describe a partial implementation of the architecture, and give a preliminary analysis based on our experiences.},
  year = {2012},
}
Moodley D, Simonis I, Tapamo JR. An architecture for managing knowledge and system dynamism in the worldwide Sensor Web. International Journal of Semantic Web and Information Systems: Special issue on Semantics-enhanced Sensor Networks, Internet of Things and Smart Devices. 2012;8(1). http://www.igi-global.com/article/architecture-managing-knowledge-system-dynamism/70587.

Sensor Web researchers are currently investigating middleware to aid in the dynamic discovery, integration and analysis of vast quantities of both high and low quality, but distributed and heterogeneous earth observation data. Key challenges being investigated include dynamic data integration and analysis, service discovery and semantic interoperability. However, few efforts deal with managing knowledge and system dynamism. Two emerging technologies that have shown promise in dealing with these issues are ontologies and software agents. This paper presents an integrated ontology driven agent based Sensor Web architecture for managing knowledge and system dynamism. An application case study on wildfire detection is used to illustrate the operation of the architecture.

@article{8,
  author = {Deshen Moodley and I. Simonis and J. Tapamo},
  title = {An architecture for managing knowledge and system dynamism in the worldwide Sensor Web},
  abstract = {Sensor Web researchers are currently investigating middleware to aid in the dynamic discovery, integration and analysis of vast quantities of both high and low quality, but distributed and heterogeneous earth observation data. Key challenges being investigated include dynamic data integration and analysis, service discovery and semantic interoperability. However, few efforts deal with managing knowledge and system dynamism. Two emerging technologies that have shown promise in dealing with these issues are ontologies and software agents. This paper presents an integrated ontology driven agent based Sensor Web architecture for managing knowledge and system dynamism. An application case study on wildfire detection is used to illustrate the operation of the architecture.},
  year = {2012},
  journal = {International Journal of Semantic Web and Information Systems: Special issue on Semantics-enhanced Sensor Networks, Internet of Things and Smart Devices},
  volume = {8},
  pages = {64-88},
  issue = {1},
  url = {http://www.igi-global.com/article/architecture-managing-knowledge-system-dynamism/70587},
}
Casini G, Gerber A, Meyer T. A Note on the Translation of Conceptual Data Models into Description Logics: Disjointness and Covering Assumptions. In: South African Institute for Computer Scientists and Information Technologists (SAICSIT). ; 2012.

Conceptual modeling is nowadays mostly done using languages such as Entity-Relationship (ER) Models, Unified Modeling Language (UML), and Object-Role Modeling (ORM). These models are used to depict the ontological organization of relevant concepts or entities. Such models share a common modeling approach, based on the notions of class or entity and the relations or associations between classes or entities. Recent developments in knowledge representation using logic-based ontologies have created new possibilities for conceptual data modeling. It also raises the question of how existing conceptual models using ER, UML or ORM could be translated into Description Logics (DLs), a family of logics that have proved to be particularly appropriate for formalizing ontologies and reasoning about them. Given a conceptual data model, two assumptions are usually made that are not explicitly stated but need to be clarified for its DL translation: (1) disjointness assumption: all the classes are to be assumed pairwise disjoint if not specified otherwise; and (2) covering assumption: the content of every class must correspond to the union of its immediate subclasses (this includes the assumption that we do not consider anything apart from what is expressed in the model). In this paper we propose two simple procedures to assist modelers with integrating these assumptions into their models, thereby allowing for a more complete translation into DLs.

@{7,
  author = {Giovanni Casini and Aurona Gerber and Thomas Meyer},
  title = {A Note on the Translation of Conceptual Data Models into Description Logics: Disjointness and Covering Assumptions},
  abstract = {Conceptual modeling is nowadays mostly done using languages such as Entity-Relationship (ER) Models, Unified Modeling Language (UML), and Object-Role Modeling (ORM). These models are used to depict the ontological organization of relevant concepts or entities. Such models share a common modeling approach, based on the notions of class or entity and the relations or associations between classes or entities. Recent developments in knowledge representation using logic-based ontologies have created new possibilities for conceptual data modeling. It also raises the question of how existing conceptual models using ER, UML or ORM could be translated into Description Logics (DLs), a family of logics that have proved to be particularly appropriate for formalizing ontologies and reasoning about them. Given a conceptual data model, two assumptions are usually made that are not explicitly stated but need to be clarified for its DL translation:
(1) disjointness assumption: all the classes are to be assumed pairwise disjoint if not specified otherwise; and (2) covering assumption: the content of every class must correspond to the union of its immediate subclasses (this includes the assumption that we do not consider anything apart from what is expressed in the model). In this paper we propose two simple procedures to assist modelers with integrating these assumptions into their models, thereby allowing for a more complete translation into DLs.},
  year = {2012},
  journal = {South African Institute for Computer Scientists and Information Technologists (SAICSIT)},
}
Keet M. Detecting and Revising Flaws in OWL Object Property Expressions. In: 18th International Conference on Knowledge Engineering and Knowledge Management (EKAW'12), A. ten Teije et al. (Eds.). Oct 8-12, Galway, Ireland. Lecture Notes in Artificial Intelligence LNAI 7603. ; 2012.

OWL 2 DL is a very expressive language and has many fea- tures for declaring complex object property expressions. Standard rea- soning services for OWL ontologies assume the axioms in the ‘object property box’ to be correct and according to the ontologist’s intention. However, the more one can do, the higher the chance modelling flaws are introduced; hence, an unexpected or undesired classification or inconsis- tency may actually be due to a mistake in the object property box, not the class axioms. We identify the types of flaws that can occur in the object property box and propose corresponding compatibility services, SubProS and ProChainS, that check for meaningful property hierarchies and property chaining and propose how to revise a flaw. SubProS and ProChainS were evaluated with several ontologies, demonstrating they indeed do serve to isolate flaws and can propose useful corrections.

@{6,
  author = {Maria Keet},
  title = {Detecting and Revising Flaws in OWL Object Property Expressions},
  abstract = {OWL 2 DL is a very expressive language and has many fea- tures for declaring complex object property expressions. Standard rea- soning services for OWL ontologies assume the axioms in the ‘object property box’ to be correct and according to the ontologist’s intention. However, the more one can do, the higher the chance modelling flaws are introduced; hence, an unexpected or undesired classification or inconsis- tency may actually be due to a mistake in the object property box, not the class axioms. We identify the types of flaws that can occur in the object property box and propose corresponding compatibility services, SubProS and ProChainS, that check for meaningful property hierarchies and property chaining and propose how to revise a flaw. SubProS and ProChainS were evaluated with several ontologies, demonstrating they indeed do serve to isolate flaws and can propose useful corrections.},
  year = {2012},
  journal = {18th International Conference on Knowledge Engineering and Knowledge Management (EKAW'12), A. ten Teije et al. (Eds.). Oct 8-12, Galway, Ireland. Lecture Notes in Artificial Intelligence LNAI 7603},
}

2011

Nortjé R. Module extraction for inexpressive description logics. 2011;MSc.

No Abstract

@phdthesis{88,
  author = {Riku Nortjé},
  title = {Module extraction for inexpressive description logics},
  abstract = {No Abstract},
  year = {2011},
  volume = {MSc},
}
Hastings J, Britz K. Representing chemical structures using OWL and description graphs. 2011;MSc.

No Abstract

@phdthesis{87,
  author = {J. Hastings and Katarina Britz},
  title = {Representing chemical structures using OWL and description graphs},
  abstract = {No Abstract},
  year = {2011},
  volume = {MSc},
}
Khan ZC, Keet M. Extending ontology development methodologies with foundational ontologies. 2011;Honours.

From studies, it is clear that using a foundational ontology for domain ontology development is beneficial in theory and practice. However, when it is to be used, developers don't know which one to choose and why. In order to solve this problem, a comprehensive set of criteria that in influence foundational ontology selection has been compiled and a corresponding software tool has been developed to help a domain ontology developer to choose one. This report presents ONSET: a tool used for foundational ontology selection in domain ontology development. Based on an ontology developer's preferences such as ontological commitments, representation languages and other factors, ONSET selects an appropriate foundational ontology to be used for the domain ontology to be developed.

@phdthesis{83,
  author = {Zubeida Khan and Maria Keet},
  title = {Extending ontology development methodologies with foundational ontologies},
  abstract = {From studies, it is clear that using a foundational ontology for domain ontology development is beneficial in theory and practice. However, when it is to be used, developers don't know which one to choose and why. In order to solve this problem, a comprehensive set of criteria that in influence foundational ontology selection has been compiled and a corresponding software tool has been developed to help a domain ontology developer to choose one. This report presents ONSET: a tool used for foundational ontology selection in domain ontology development. Based on an ontology developer's preferences such as ontological commitments, representation languages and other factors, ONSET selects an appropriate foundational ontology to be used for the domain ontology to be developed.},
  year = {2011},
  volume = {Honours},
}
Moodley K. Debugging and Repair of Description Logic Ontologies. 2011;MSc. http://ksg.meraka.org.za/~kmoodley/MSc%20Dissertation%20-%20KMoodley.pdf.

In logic-based Knowledge Representation and Reasoning (KRR), ontologies are used to represent knowledge about a particular domain of interest in a precise way. The building blocks of ontologies include concepts, relations and objects. Those can be combined to form logical sentences which explicitly describe the domain. With this explicit knowledge one can perform reasoning to derive knowledge that is implicit in the ontology. Description Logics (DLs) are a group of knowledge representation languages with such capabilities that are suitable to represent ontologies. The process of building ontologies has been greatly simpli ed with the advent of graphical ontology editors such as SWOOP, Protege and OntoStudio. The result of this is that there are a growing number of ontology engineers attempting to build and develop ontologies. It is frequently the case that errors are introduced while constructing the ontology resulting in undesirable pieces of implicit knowledge that follows from the ontology. As such there is a need to extend current ontology editors with tool support to aid these ontology engineers in correctly designing and debugging their ontologies. Errors such as unsatis able concepts and inconsistent ontologies frequently occur during ontology construction. Ontology Debugging and Repair is concerned with helping the ontology developer to eliminate these errors from the ontology. Much emphasis, in current tools, has been placed on giving explanations as to why these errors occur in the ontology. Less emphasis has been placed on using this information to suggest ecient ways to eliminate the errors. Furthermore, these tools focus mainly on the errors of unsatis able concepts and inconsistent ontologies. In this dissertation we ll an important gap in the area by contributing an alternative approach to ontology debugging and repair for the more general error of a list of unwanted sentences. Errors such as unsatis able concepts and inconsistent ontologies can be represented as unwanted sentences in the ontology. Our approach not only considers the explanation of the unwanted sentences but also the identi cation of repair strategies to eliminate these unwanted sentences from the ontology.

@phdthesis{33,
  author = {Kody Moodley},
  title = {Debugging and Repair of Description Logic Ontologies},
  abstract = {In logic-based Knowledge Representation and Reasoning (KRR), ontologies are used to
represent knowledge about a particular domain of interest in a precise way. The building
blocks of ontologies include concepts, relations and objects. Those can be combined to
form logical sentences which explicitly describe the domain. With this explicit knowledge
one can perform reasoning to derive knowledge that is implicit in the ontology. Description
Logics (DLs) are a group of knowledge representation languages with such capabilities that
are suitable to represent ontologies. The process of building ontologies has been greatly
simplied with the advent of graphical ontology editors such as SWOOP, Protege and
OntoStudio. The result of this is that there are a growing number of ontology engineers
attempting to build and develop ontologies. It is frequently the case that errors are
introduced while constructing the ontology resulting in undesirable pieces of implicit
knowledge that follows from the ontology. As such there is a need to extend current
ontology editors with tool support to aid these ontology engineers in correctly designing
and debugging their ontologies. Errors such as unsatisable concepts and inconsistent
ontologies frequently occur during ontology construction. Ontology Debugging and Repair
is concerned with helping the ontology developer to eliminate these errors from the ontology.
Much emphasis, in current tools, has been placed on giving explanations as to why these
errors occur in the ontology. Less emphasis has been placed on using this information to
suggest ecient ways to eliminate the errors. Furthermore, these tools focus mainly on the
errors of unsatisable concepts and inconsistent ontologies. In this dissertation we ll an
important gap in the area by contributing an alternative approach to ontology debugging
and repair for the more general error of a list of unwanted sentences. Errors such as
unsatisable concepts and inconsistent ontologies can be represented as unwanted sentences
in the ontology. Our approach not only considers the explanation of the unwanted sentences
but also the identication of repair strategies to eliminate these unwanted sentences from
the ontology.},
  year = {2011},
  volume = {MSc},
  url = {http://ksg.meraka.org.za/~kmoodley/MSc%20Dissertation%20-%20KMoodley.pdf},
}
Moodley K, Meyer T, Varzinczak I. Root Justifications for Ontology Repair. In: Fifth International Conference on Web Reasoning and Rule Systems. ; 2011.

No Abstract

@{32,
  author = {Kody Moodley and Thomas Meyer and Ivan Varzinczak},
  title = {Root Justifications for Ontology Repair},
  abstract = {No Abstract},
  year = {2011},
  journal = {Fifth International Conference on Web Reasoning and Rule Systems},
  pages = {275-280},
}
Nortjé R, Britz K, Meyer T. Bidirectional reachability-based modules. 24th International Workshop on Description Logics (DL 2011). 2011.

We introduce an algorithm for MinA extraction in EL based on bidirectional reachability. We obtain a significant reduction in the size of modules extracted at almost no additional cost to that of extracting standard reachability-based modules. Bidirectional modules are related to nested locality modules, but are aimed specifically at MinA extraction and are generally smaller. For acyclic EL TBoxes consisting of only primitive concept inclusions, all MinAs can be extracted without the need for subsumption testing.

@misc{30,
  author = {Riku Nortjé and Katarina Britz and Thomas Meyer},
  title = {Bidirectional reachability-based modules},
  abstract = {We introduce an algorithm for MinA extraction in EL based on bidirectional reachability. We obtain a significant reduction in the size of modules extracted at almost no additional cost to that of extracting standard reachability-based modules. Bidirectional modules are related to nested locality modules, but are aimed specifically at MinA extraction and are generally smaller. For acyclic EL TBoxes consisting of only primitive concept inclusions, all MinAs can be extracted without the need for subsumption testing.},
  year = {2011},
  journal = {24th International Workshop on Description Logics (DL 2011)},
  month = {13/07 - 16/07},
}
Halland K, Britz K, Gerber A. Investigations into the use of SNOMED CT to enhance an Open-MRS health information system. South African Computer Journal. 2011;47.

No Abstract

@article{29,
  author = {Ken Halland and Katarina Britz and Aurona Gerber},
  title = {Investigations into the use of SNOMED CT to enhance an Open-MRS health information system},
  abstract = {No Abstract},
  year = {2011},
  journal = {South African Computer Journal},
  volume = {47},
  pages = {33-46},
}
Britz K, Meyer T, Varzinczak I. Concept Model Semantics for DL Preferential Reasoning. 24th International Workshop on Description Logics (DL 2011). 2011.

The preferential and rational consequence relations first studied by Lehmann and colleagues play a central role in non-monotonic reasoning, not least because they provide the foundation for the determination of the important notion of rational closure. Although they can be applied directly to a large variety of logics, these constructions suffer from the limitation that they are largely propositional in nature. One of the main obstacles in moving beyond the propositional case has been the lack of a formal semantics which appropriately generalizes the preferential and ranked models of Lehmann et al. In this paper we propose a semantics to fill that gap for description logics, an important class of decidable fragments of first-order logic. Our semantics replaces the propositional valuations used in the models of Lehmann et al. with structures we refer to as concept models. We prove representation results for the description logic ALC for both preferential and rational consequence relations. We argue that our semantics paves the way for extending preferential and rational consequence, and therefore also rational closure, to a whole class of logics that have a semantics defined in terms of first-order relational structures.

@misc{28,
  author = {Katarina Britz and Thomas Meyer and Ivan Varzinczak},
  title = {Concept Model Semantics for DL Preferential Reasoning},
  abstract = {The preferential and rational consequence relations first studied by Lehmann and colleagues play a central role in non-monotonic reasoning, not least because they provide the foundation for the determination of the important notion of rational closure. Although they can be applied directly to a large variety of logics, these constructions suffer from the limitation that they are largely propositional in nature. One of the main obstacles in moving beyond the propositional case has been the lack of a formal semantics which appropriately generalizes the preferential and ranked models of Lehmann et al. In this paper we propose a semantics to fill that gap for description logics, an important class of decidable fragments of first-order logic. Our semantics replaces the propositional valuations used in the models of Lehmann et al. with structures we refer to as concept models. We prove representation results for the description logic ALC for both preferential and rational consequence relations. We argue that our semantics paves the way for extending preferential and rational consequence, and therefore also rational closure, to a whole class of logics that have a semantics defined in terms of first-order relational structures.},
  year = {2011},
  journal = {24th International Workshop on Description Logics (DL 2011)},
  month = {13/07 - 16/07},
}
Britz K, Meyer T, Varzinczak I. Semantic Foundation for Preferential Description Logics. In: Proceedings of the 24th Australasian Joint Conference on Artificial Intelligence. ; 2011.

Description logics are a well-established family of knowledge representation formalisms in Artificial Intelligence. Enriching description logics with non-monotonic reasoning capabilities, especially preferential reasoning as developed by Lehmann and colleagues in the 90's, would therefore constitute a natural extension of such KR formalisms. Nevertheless, there is at present no generally accepted semantics, with corresponding syntactic characterization, for preferential consequence in description logics. In this paper we fill this gap by providing a natural and intuitive semantics for defeasible subsumption in the description logic ALC. Our semantics replaces the propositional valuations used in the models of Lehmann et al. with structures we refer to as concept models. We present representation results for the description logic ALC for both preferential and rational consequence relations. We argue that our semantics paves the way for extending preferential and rational consequence, and therefore also rational closure, to a whole class of logics that have a semantics defined in terms of first-order relational structures.

@{27,
  author = {Katarina Britz and Thomas Meyer and Ivan Varzinczak},
  title = {Semantic Foundation for Preferential Description Logics},
  abstract = {Description logics are a well-established family of knowledge representation formalisms in Artificial Intelligence. Enriching description logics with non-monotonic reasoning capabilities, especially preferential reasoning as developed by Lehmann and colleagues in the 90's, would therefore constitute a natural extension of such KR formalisms. Nevertheless, there is at present no generally accepted semantics, with corresponding syntactic characterization, for preferential consequence in description logics. In this paper we fill this gap by providing a natural and intuitive semantics for defeasible subsumption in the description logic ALC. Our semantics replaces the propositional valuations used in the models of Lehmann et al. with structures we refer to as concept models. We present representation results for the description logic ALC for both preferential and rational consequence relations. We argue that our semantics paves the way for extending preferential and rational consequence, and therefore also rational closure, to a whole class of logics that have a semantics defined in terms of first-order relational structures.},
  year = {2011},
  journal = {Proceedings of the 24th Australasian Joint Conference on Artificial Intelligence},
  pages = {491-500},
}
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