Research Publications

SLAOP is the Specication Logic of Actions and Observations with Probability. In this report, we provide the syntax and semantics of SLAOP and then provide a decision procedure for checking validity of sentences. The decision procedure is a tableau method which appeals to solving systems of equations. The tableau rules eliminate propositional connectives, then, for all open branches of the tableau tree, systems of equations are generated and checked for feasibility. We prove that the procedure is sound and complete.

@misc{59,
  author = {Gavin Rens and Tommie Meyer and G. Lakemeyer},
  title = {A Sound, Complete and Terminating Decision Procedure for SLAOP},
  abstract = {SLAOP is the Specication Logic of Actions and Observations with Probability. In this report, we provide the syntax and semantics of SLAOP and then provide a decision procedure for checking validity of sentences. The decision procedure is a tableau method which appeals to solving systems of equations. The tableau rules eliminate propositional connectives, then, for all open branches of the tableau tree, systems of equations are generated and checked for feasibility. We prove that the procedure is sound and complete.},
  year = {2013},
}

The notion behind foundational ontologies is to have a single foundational ontology to serve as a basis for providing high-level entities and relations that are common between all ontologies in order to facilitate interoperability among heterogeneous systems. However foundational ontologies alone do not suffice in solving the problem of interoperability, due to the fact that many foundational ontologies exist, each with conflicting philosophies. The WonderWeb Foundational Ontologies Library (WFOL) was envisioned to facilitate interoperability, but not implemented, possibly due to a lack of: ontology mediation (alignment, mapping and merging) techniques, documentation and comparisons between foundational ontologies and modularisation techniques. In order to solve this problem, three widely used foundational ontologies: DOLCE, BFO and GFO were selected and a web-based repository, ROMULUS was created. Ontology mediation was performed to assist in achieving foundational ontology interchangeability between the selected foundational ontologies. Modularity was performed to simplify ontologies in order to easily perform mediation and to create modules for specific functions. ROMULUS provides the user with access to: new foundational ontology modules, mappings between foundational ontologies, merged foundational ontologies, a higher level foundational ontology containing only the most general entities common to the three foundational ontologies and a method to assist the user with performing foundational ontology interchangeability. The new modules in ROMULUS (separate endurant/perdurant modules, OWL 2 profile modules, and more/less-detailed ontology modules) are useful when one wants to perform functionality specific to the module type. The mapping and merged ontologies, which may be used together with the method for performing foundational ontology interchangeability, allow a user to convert between the three foundational ontologies and to link an ontology using a particular foundational ontology to a different ontology that uses another foundational ontology, thereby achieving transparency. The higher level foundational ontology may assist in interoperability because it is a single ontology that encompasses entities that are common between all three foundational ontologies. ROMULUS has been evaluated in terms of its foundational ontology interchangeability, accuracy of alignments and by comparing it to other repositories. From the evaluations, we realised the following: While barely 50\% of the participants agreed with the alignments, real disagreement was less than 10\%; foundational ontology interchangeability may be achieved using the merged ontologies; ROMULUS offers advanced functionality for most criteria when compared to other repositories. Therefore there is reason to believe that ROMULUS does assist with foundational ontology interoperability.

@phdthesis{57,
  author = {Zubeida Khan},
  title = {Foundational Ontology Interchangeability with the Repository of Ontologies for MULtiple USes (ROMULUS)},
  abstract = {The notion behind foundational ontologies is to have a single foundational ontology to serve as a basis for providing high-level entities and relations that are common between all ontologies in order to facilitate interoperability among heterogeneous systems. However foundational ontologies alone do not suffice in solving the problem of interoperability, due to the fact that many foundational ontologies exist, each with conflicting philosophies. The WonderWeb Foundational Ontologies Library (WFOL) was envisioned to facilitate interoperability, but not implemented, possibly due to a lack of: ontology mediation (alignment, mapping and merging) techniques, documentation and comparisons between foundational ontologies and modularisation techniques. In order to solve this problem, three widely used foundational ontologies: DOLCE, BFO and GFO were selected and a web-based repository, ROMULUS was created. Ontology mediation was performed to assist in achieving foundational ontology interchangeability between the selected foundational ontologies. Modularity was performed to simplify ontologies in order to easily perform mediation and to create modules for specific functions. ROMULUS provides the user with access to: new foundational ontology modules, mappings between foundational ontologies, merged foundational ontologies, a higher level foundational ontology containing only the most general entities common to the three foundational ontologies and a method to assist the user with performing foundational ontology interchangeability. The new modules in ROMULUS (separate endurant/perdurant modules, OWL 2 profile modules, and more/less-detailed ontology modules) are useful when one wants to perform functionality specific to the module type. The mapping and merged ontologies, which may be used together with the method for performing foundational ontology interchangeability, allow a user to convert between the three foundational ontologies and to link an ontology using a particular foundational ontology to a different ontology that uses another foundational ontology, thereby achieving transparency. The higher level foundational ontology may assist in interoperability because it is a single ontology that encompasses entities that are common between all three foundational ontologies. ROMULUS has been evaluated in terms of its foundational ontology interchangeability, accuracy of alignments and by comparing it to other repositories. From the evaluations, we realised the following: While barely 50\% of the participants agreed with the alignments, real disagreement was less than 10\%; foundational ontology interchangeability may be achieved using the merged ontologies; ROMULUS offers advanced functionality for most criteria when compared to other repositories. Therefore there is reason to believe that ROMULUS does assist with foundational ontology interoperability.},
  year = {2013},
  volume = {MSc},
}

An approach in achieving semantic interoperability among heterogeneous systems is to offer infrastructure to assist with linking and integration using a foundational ontology. Due to the creation of multiple foundational ontologies, this also means linking and integrating those ones. In order to achieve this, we have selected the widely used foundational ontologies DOLCE, BFO, and GFO, and their related modules, on which to perform ontology mediation (alignment, mapping, and merging). The foundational ontologies were aligned by identifying correspondences between ontology entities using seven tools, documentation, and our manual alignments, and comparing their effectiveness. Thereafter, based on the alignments, we created correspondences in the ontology files resulting in entity mappings and merged ontologies. However, during the mapping process, it was found that differences in foundational ontologies, such as their hierarchical structure, conflicting axioms due to complement and disjointness, and incompatible domain and range restriction, cause logical inconsistencies in foundational ontology alignments, thereby greatly reducing the number of mappings. We analyse and present these logical inconsistencies with possible solutions to some of them.

@{56,
  author = {Zubeida Khan and Maria Keet},
  title = {Addressing Issues in Foundational Ontology Mediation},
  abstract = {An approach in achieving semantic interoperability among heterogeneous systems is to offer infrastructure to assist with linking and integration using a foundational ontology. Due to the creation of multiple foundational ontologies, this also means linking and integrating those ones. In order to achieve this, we have selected the widely used foundational ontologies DOLCE, BFO, and GFO, and their related modules, on which to perform ontology mediation (alignment, mapping, and merging). The foundational ontologies were aligned by identifying correspondences between ontology entities using seven tools, documentation, and our manual alignments, and comparing their effectiveness. Thereafter, based on the alignments, we created correspondences in the ontology files resulting in entity mappings and merged ontologies. However, during the mapping process, it was found that differences in foundational ontologies, such as their hierarchical structure, conflicting axioms due to complement and disjointness, and incompatible domain and range restriction, cause logical inconsistencies in foundational ontology alignments, thereby greatly reducing the number of mappings. We analyse and present these logical inconsistencies with possible solutions to some of them.},
  year = {2013},
  journal = {5th International Conference on Knowledge Engineering and Ontology Development (KEOD'13)},
}

A purpose of a foundational ontology is to solve interoperability issues among ontologies. Many foundational ontologies have been developed, re-introducing the ontology interoperability problem. We address this with the new online foundational ontology repository ROMULUS, in which DOLCE, BFO and GFO have been aligned. We summarise the alignments, mappings, and logical inconsistencies of the foundational ontologies, and OMULUS's features.

@{55,
  author = {Zubeida Khan and Maria Keet},
  title = {Toward semantic interoperability with linked foundational ontologies in ROMULUS},
  abstract = {A purpose of a foundational ontology is to solve interoperability issues among ontologies. Many foundational ontologies have been developed, re-introducing the ontology interoperability problem. We address this with the new online foundational ontology repository ROMULUS, in which
DOLCE, BFO and GFO have been aligned. We summarise the alignments, mappings, and logical inconsistencies of the foundational ontologies, and OMULUS's features.},
  year = {2013},
  journal = {Seventh International Conference on Knowledge Capture (KCAP'13)},
}

A purpose of a foundational ontology is to solve interoperability issues among domain ontologies and they are used for ontology-driven conceptual data modelling. Multiple foundational ontologies have been developed in recent years, and most of them are available in several versions. This has re-introduced the interoperability problem, increased the need for a coordinated and structured comparison and elucidation of modelling decisions, and raised the requirement for software infrastructure to address this. We present here a basic step in that direction with the Repository of Ontologies for MULtiple USes, ROMULUS, which is the first online library of machine-processable, modularised, aligned, and logic-based merged foundational ontologies. In addition to the typical features of a model repository, it has a foundational ontology recommender covering features of six foundational ontologies, tailor-made modules for easier reuse, and a catalogue of interesting mappable and non-mappable elements among the BFO, GFO and DOLCE foundational ontologies.

@{54,
  author = {Zubeida Khan and Maria Keet},
  title = {The foundational ontology library ROMULUS},
  abstract = {A purpose of a foundational ontology is to solve interoperability issues among domain ontologies and they are used for ontology-driven conceptual data modelling. Multiple foundational ontologies have been developed in recent years, and most of them are available in several versions. This has re-introduced the interoperability problem, increased the need for a coordinated and structured comparison and elucidation of modelling decisions, and raised the requirement for software infrastructure to address this. We present here a basic step in that direction with the Repository of Ontologies for MULtiple USes, ROMULUS, which is the first online library of machine-processable, modularised, aligned, and logic-based merged foundational ontologies. In addition to the typical features of a model repository, it has a foundational ontology recommender covering features of six foundational ontologies, tailor-made modules for easier reuse, and a catalogue of interesting mappable and non-mappable elements among the BFO, GFO and DOLCE foundational ontologies.},
  year = {2013},
  journal = {3rd International Conference on Model & Data Engineering (MEDI’13)},
}

A significant challenge that faces IT management is that of aligning the IT infrastructure of an enterprise with its business goals and practices, also called business-IT alignment. A particular business-IT alignment approach, the foundation for execution approach, was well-accepted by practitioners due to a novel construct, called the operating model (OM). The OM supports business-IT alignment by directing the coherent and consistent design of business and IT components. Even though the OM is a popular construct, our previous research detected the need to enhance the OM, since the OM does not specify methods to identify opportunities for data sharing and process reuse in an enterprise. In this article, we address one of the identified deficiencies in the OM. We present a process reuse identification framework (PRIF) that could be used to enhance the OM in identifying process reuse opportunities in an enterprise. We applied design research to develop PRIF as an artefact, where the development process of PRIF was facilitated by means of the business-IT alignment model (BIAM). We demonstrate the use of the PRIF as well as report on the results of evaluating PRIF in terms of its usefulness and ease-of-use, using experimentation and a questionnaire.

@article{53,
  author = {Marne de Vries and Aurona Gerber and Alta van der Merwe},
  title = {A framework for the identification of reusable processes},
  abstract = {A significant challenge that faces IT management is that of aligning the IT infrastructure of an enterprise with its business goals and practices, also called business-IT alignment. A particular business-IT alignment approach, the foundation for execution approach, was well-accepted by practitioners due to a novel construct, called the operating model (OM). The OM supports business-IT alignment by directing the coherent and consistent design of business and IT components. Even though the OM is a popular construct, our previous research detected the need to enhance the OM, since the OM does not specify methods to identify opportunities for data sharing and process reuse in an enterprise. In this article, we address one of the identified deficiencies in the OM. We present a process reuse identification framework (PRIF) that could be used to enhance the OM in identifying process reuse opportunities in an enterprise. We applied design research to develop PRIF as an artefact, where the development process of PRIF was facilitated by means of the business-IT alignment model (BIAM). We demonstrate the use of the PRIF as well as report on the results of evaluating PRIF in terms of its usefulness and ease-of-use, using experimentation and a questionnaire.},
  year = {2013},
  journal = {Enterprise Information Systems},
  volume = {7},
  issue = {1},
  isbn = {1751-7583 (Online)},
  url = {http://www.tandfonline.com/doi/abs/10.1080/17517575.2013.805247#.UcgxlOsh4sc},
}

In this paper we investigate the module-theoretic properties of bot and top-reachability modules in terms of inseparability relations for the DL SRIQ. We show that, although these modules are not depleting or self-contained, they share the robustness properties of syntactic locality modules and preserve all justifications for an entailment.

@misc{52,
  author = {Riku Nortjé and Katarina Britz and Tommie Meyer},
  title = {Module-theoretic properties of reachability modules for SRIQ},
  abstract = {In this paper we investigate the module-theoretic properties of bot and top-reachability modules in terms of inseparability relations for the DL SRIQ. We show that, although these modules are not depleting or self-contained, they share the robustness properties of syntactic locality modules and preserve all justifications for an entailment.},
  year = {2013},
}

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 more 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 fully integrated national health information system without substantial re-engineering; 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 the ISO/IEC/IEEE 42010 standard architecture descriptions. The architecture takes an Enterprise Service Bus approach. A partial implementation and preliminary analysis of the architecture is given. Since these challenges are experienced by other developing African countries, the next steps involves creating a generic architecture that can be reused for health information exchange in other developing African countries.

@inbook{51,
  author = {Ryan Crichton and Deshen Moodley and Anban Pillay and Chris Seebregts},
  title = {An Architecture and Reference Implementation of an Open Health Information Mediator: Enabling Interoperability in the Rwandan Health Information Exchange},
  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 more 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 fully integrated national health information system without substantial re-engineering; 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 the ISO/IEC/IEEE 42010 standard architecture descriptions. The architecture takes an Enterprise Service Bus approach. A partial implementation and preliminary analysis of the architecture is given. Since these challenges are experienced by other developing African countries, the next steps involves creating a generic architecture that can be reused for health information exchange in other developing African countries.},
  year = {2013},
  journal = {Foundations of Health Information Engineering and Systems, Revised and Selected Papers, Lecture Notes in Computer Science Volume 7789},
  pages = {87-104},
  publisher = {Springer Berlin Heidelberg},
  isbn = {978-3-642-39087-6},
  url = {http://link.springer.com/chapter/10.1007/978-3-642-39088-3_6},
}

The introduction of defeasible reasoning in Description Logics has been a main research topic in the field in the last years. Despite the fact that various interesting formalizations of nonmonotonic reasoning for the TBox have been proposed, the application of such a kind of reasoning also to ABoxes is more problematic. In what follows we are going to present the adaptation for the ABox of a classical nonmonotonic form of reasoning, Lehmann and Magidor’s Rational Closure.We present both a procedural and a semantical characterization, and we conclude the paper with a comparison between our and other analogous proposals.

@misc{47,
  author = {Giovanni Casini and Tommie Meyer and Kody Moodley and Ivan Varzinczak},
  title = {Nonmonotonic reasoning in Description Logics. Rational Closure for the ABox.},
  abstract = {The introduction of defeasible reasoning in Description Logics has been a main research topic in the field in the last years. Despite the fact that various interesting formalizations of nonmonotonic reasoning for the TBox have been proposed, the application of such a kind of reasoning also to ABoxes is more problematic. In what follows we are going to present the adaptation for the ABox of a classical nonmonotonic form of reasoning, Lehmann and Magidor’s Rational Closure.We present both a procedural and a semantical characterization, and we conclude the paper with a comparison between our and other analogous proposals.},
  year = {2013},
  journal = {26th International Workshop on Description Logics},
  month = {23/07 - 26/07},
}

The formalisation of defeasible reasoning in automated systems is becoming increasingly important. Description Logics (DLs) are nowadays the main logical formalism in the field of formal ontologies. Our focus in this paper is to devise a practical implementation for prior work that formalises a version of Rational Closure (an important type of defeasible reasoning) for DLs. We show that the conclusions drawn from it are generally intuitive and desirable. Moreover, we present experimental results showing that using Rational Closure for ontologies of reasonable size is practical.

@misc{46,
  author = {Giovanni Casini and Tommie Meyer and Kody Moodley and Ivan Varzinczak},
  title = {Towards Practical Defeasible Reasoning for Description Logics},
  abstract = {The formalisation of defeasible reasoning in automated systems is becoming increasingly important. Description Logics (DLs) are nowadays the main logical formalism in the field of formal ontologies. Our focus in this paper is to devise a practical implementation for prior work that formalises a version of Rational Closure (an important type of defeasible reasoning) for DLs. We show that the conclusions drawn from it are generally intuitive and desirable. Moreover, we present experimental results showing that using Rational Closure for ontologies of reasonable size is practical.},
  year = {2013},
  journal = {26th International Workshop on Description Logics},
  month = {23/07 - 26/07},
}

We extend the Description Logic ALC with preferential role restrictions as class constructs, and argue that preferential universal restriction represents a defeasible version of standard universal restriction. The resulting DL is more expressive without adding to the complexity of TBox reasoning. We present a tableau system to compute TBox entailment, show that this notion of entailment is not sufficient when adding ABoxes, and refine entailment to deal adequately with ABox reasoning.

@misc{45,
  author = {Katarina Britz and Giovanni Casini and Tommie Meyer and Ivan Varzinczak},
  title = {Preferential Role Restrictions},
  abstract = {We extend the Description Logic ALC with preferential role restrictions as class constructs, and argue that preferential universal restriction represents a defeasible version of standard universal restriction. The resulting DL is more expressive without adding to the complexity of TBox reasoning. We present a tableau system to compute TBox entailment, show that this notion of entailment is not sufficient when adding ABoxes, and refine entailment to deal adequately with ABox reasoning.},
  year = {2013},
  journal = {26th International Workshop on Description Logics},
  month = {23/07 - 26/07},
}

We investigate the requirements for specifying the behaviors of actions in a stochastic domain. That is, we propose how to write sentences in a logical language to capture a model of probabilistic transitions due to the execution of actions of some agent.We propose a definition for ‘proper’ and ‘full’ probabilistic transition model specifications and suggest which assumptions can and perhaps should be made about such specifications to make them more parsimonious. Making a priori or default assumptions about the nature of transitions is useful when a given transition model is not fully specified. Two default assumption approaches will be considered.

@misc{44,
  author = {Gavin Rens and Tommie Meyer and G. Lakemeyer},
  title = {On the Logical Specification of Probabilistic Transition Models},
  abstract = {We investigate the requirements for specifying the behaviors of actions in a stochastic domain. That is, we propose how to write sentences in a logical language to capture a model of probabilistic transitions due to the execution of actions of some agent.We propose a definition for ‘proper’ and ‘full’ probabilistic transition model specifications and suggest which assumptions can and perhaps should be made about such specifications to make them more parsimonious. Making a priori or default assumptions about the nature of transitions is useful when a given transition model is not fully specified. Two default assumption approaches will be considered.},
  year = {2013},
  journal = {Commonsense-2013},
}

The domain complexity and structural- and semantic heterogeneity of biodiversity data, as well as idiosyncratic legacy data-creation processes, present significant integration and interoperability challenges. In this paper we describe a case study of ontology-driven semantic mediation using records of flower-visiting insects from three natural history collections in South Africa. We establish a conceptual domain model for flower-visiting, expressed in an OWL ontology, and use it to semantically enrich the three data-stores. We show how this enrichment allows for the creation of an integrated flower visiting data set. We discuss how this ontology captures both implicit and explicit knowledge, how it can be used to identify and analyze high level flower-visiting behaviour, and ultimately to construct flower-visiting and pollination networks.

@misc{43,
  author = {Willem Coetzer and Deshen Moodley and Aurona Gerber},
  title = {A Case-Study of Ontology-Driven Semantic Mediation of Flower-Visiting Data from Heterogeneous Data-Stores in Three South African Natural History Collections},
  abstract = {The domain complexity and structural- and semantic heterogeneity of biodiversity data, as well as idiosyncratic legacy data-creation processes, present significant integration and interoperability challenges. In this paper we describe a case study of ontology-driven semantic mediation using records of flower-visiting insects from three natural history collections in South Africa. We establish a conceptual domain model for flower-visiting, expressed in an OWL ontology, and use it to semantically enrich the three data-stores. We show how this enrichment allows for the creation of an integrated flower visiting data set. We discuss how this ontology captures both implicit and explicit knowledge, how it can be used to identify and analyze high level flower-visiting behaviour, and ultimately to construct flower-visiting and pollination networks.},
  year = {2013},
  url = {http://ceur-ws.org/Vol-979/WS_s4biodiv2013_paper_5.pdf},
}

No Abstract

@misc{38,
  author = {Ivan Varzinczak},
  title = {Talk at TARK-13},
  abstract = {No Abstract},
  year = {2013},
}

Nonmonotonic logics are usually characterized by the presence of some notion of 'conditional' that fails monotonicity. Research on nonmonotonic logics is therefore largely concerned with the defeasibility of argument forms and the associated normality (or abnormality) of its constituents. In contrast, defeasible modes of inference aim to formalize the defeasible aspects of modal notions such as actions, obligations and knowledge. In this work we enrich the standard possible worlds semantics with a preference ordering on worlds in Kripke models. The resulting family of modal logics allow for the elegant expression of defeasible modalities. We also propose a tableau calculus which is sound and complete with respect to our preferential semantics.

@{36,
  author = {Katarina Britz and Ivan Varzinczak},
  title = {Defeasible Modalities},
  abstract = {Nonmonotonic logics are usually characterized by the presence of some notion of 'conditional' that fails monotonicity. Research on nonmonotonic logics is therefore largely concerned with the defeasibility of argument forms and the associated normality (or abnormality) of its constituents. In contrast, defeasible modes of inference aim to formalize the defeasible aspects of modal notions such as actions, obligations and knowledge. In this work we enrich the standard possible worlds semantics with a preference ordering on worlds in Kripke models. The resulting family of modal logics allow for the elegant expression of defeasible modalities. We also propose a tableau calculus which is sound and complete with respect to our preferential semantics.},
  year = {2013},
  journal = {14th Conference on Theoretical Aspects of Rationality and Knowledge (TARK)},
  pages = {49-60},
}

@article{595,
  author = {Renier van Heerden and Barry Irwin and Ivan Burke and Louise Leenen},
  title = {A Computer Attack Network Taxonomy and Ontology},
  abstract = {},
  year = {2012},
  journal = {International Journal of Cyber Warfare and Terrorism},
  volume = {2},
  pages = {12-25},
  issue = {3},
  publisher = {IGI Global},
}

@article{596,
  author = {Joey van Vuuren and Louise Leenen and Jackie Phahlamohlaka and Jannie Zaaiman},
  title = {An Approach to Governance of Cybersecurity in South Africa},
  abstract = {},
  year = {2012},
  journal = {International Journal of Cyber Warfare and Terrorism},
  volume = {2},
  pages = {13-27},
  issue = {4},
  publisher = {IGI Global},
}

@{594,
  author = {Marthie Grobler and Joey van Vuuren and Louise Leenen},
  title = {Implementation of a Cybersecurity Policy in South Africa: Reflection on Progress and the Way Forward},
  abstract = {},
  year = {2012},
  journal = {Proceedings of the IFIP Human Choice and Computers International Conference (HCC10 2012)},
  month = {27-28 September 2012},
  address = {Amsterdam, Netherlands},
}

@{593,
  author = {Joey van Vuuren and Jackie Phahlamohlaka and Louise Leenen},
  title = {Governance of Cyber Security in South Africa},
  abstract = {},
  year = {2012},
  journal = {Proceedings of the 11th European Conference on Information Warfare and Security (ECIW 2012)},
  month = {July 2012},
  publisher = {Academic Conferences International},
  address = {Laval, France},
}

@inbook{591,
  author = {Louise Leenen and Alex Terlunen and Herman le Roux},
  title = {A Constraint Programming Solution for the Military Unit Path Finding Problem},
  abstract = {},
  year = {2012},
  journal = {Mobile Intelligent Autonomous Systems: Recent Advances},
  month = {August 2012},
  publisher = {CRC Press},
  address = {United States of America},
}

@inbook{592,
  author = {Cobus Venter and Ignus Swart and Louise Leenen and Tommie Meyer and Jan Roodt and Herman le Roux},
  title = {Command and Control},
  abstract = {},
  year = {2012},
  journal = {South African Army Technical Symposium},
  month = {April 2012},
  publisher = {DPSS, CSIR},
  address = {South Africa},
}

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 Protege ontology editor which implements these algorithms for OWL ontologies. The plug-in is called RaMP and allows the modeller to indicate defeasible information in OWL ontologies and checkentailmentofdefeasiblesubsumptionsfromdefeasibleknowledgebases.

@misc{366,
  author = {Kody Moodley and Tommie 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 Protege ontology editor which implements these algorithms for OWL ontologies. The plug-in is called RaMP and allows the modeller to indicate defeasible information in OWL ontologies and checkentailmentofdefeasiblesubsumptionsfromdefeasibleknowledgebases.},
  year = {2012},
  journal = {Twenty Fifth International Workshop on Description Logics},
  month = {7/06 - 10/06},
  url = {https://www.researchgate.net/publication/229164089_A_Protege_Plug-in_for_Defeasible_Reasoning},
}

In recent years disciplines such as psychology, cognitive sciences and philosophy of mind have proposed alternative models to the classical view of conceptualization, that is traditionally centered on the role of definitions. Classical logic and classical set theory are no longer considered adequate tools for the formalization of the conceptual structures introduced by such new proposals. In this paper, starting from a recent work by Michael Freund, we present a logical formalization for a theory of concepts where notions such as stereotypical properties and context play a central role.

@misc{65,
  author = {Giovanni Casini},
  title = {A Preferential Proposal for Contextual Reasoning},
  abstract = {In recent years disciplines such as psychology, cognitive sciences and philosophy of mind have proposed alternative models to the classical view of conceptualization, that is traditionally centered on the role of definitions. Classical logic and classical set theory are no longer considered adequate tools for the formalization of the conceptual structures introduced by such new proposals.
In this paper, starting from a recent work by Michael Freund, we present a logical formalization for a theory of concepts where notions such as stereotypical properties and context play a central role.},
  year = {2012},
  url = {http://www.dbai.tuwien.ac.at/NMR12/proceedings.html},
}

One of the consequences of the growth in AI research in South Africa in recent years is the establishment of a number of research hubs involved in AI activities ranging from mobile robotics and computational intelligence to knowledge representation and reasoning and human language technologies. In this survey we take the reader through a quick tour of the research being conducted at these hubs and touch on an initiative to maintain and extend the current level of interest in AI research in the country.

@article{61,
  author = {Tommie Meyer and Alexander Ferrein},
  title = {A brief overview of Artificial Intelligence in South Africa},
  abstract = {One of the consequences of the growth in AI research in South Africa in recent years is the establishment of a number of research hubs involved in AI activities ranging from mobile robotics and computational intelligence to knowledge representation and reasoning and human language technologies. In this survey we take the reader through a quick tour of the research being conducted at these hubs and touch on an initiative to maintain and extend the current level of interest in AI research in the country.},
  year = {2012},
  journal = {AI Magazine},
  volume = {33},
  pages = {99-103},
  issue = {1},
  url = {http://www.aaai.org/ojs/index.php/aimagazine/article/view/2357},
}

Classical reasoning for logic-based KR (Knowledge Representation) systems is in general, monotonic. That is, there is an assumption in these systems that there is complete information about a domain. This means that they generally cannot deal with any new information arising which contradicts with the current information. This is not an appropriate model for reasoning in many applications. Therefore, alternative non-monotonic systems have been investigated which can reason under uncertainty or with incomplete information. Defeasible reasoning is one particular model for implementing non-monotonic reasoning. It is concerned with representing and reasoning with defeasible (nonstrict) facts about a domain. The defeasible counterpart of the strict fact: “All birds fly” is the defeasible fact: “Most birds fly” (or the alternative phrasing “Birds usually fly”). We discuss two approaches for defeasible reasoning in the family of logicbased KR languages known as Description Logics (DLs). They are applicable to particular extensions of DLs that allow for the statement of defeasible sentences similar to the aforementioned examples. The 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 an extension of propositional logic. Here we recast their definitions in a DL context and define algorithms for prototypical and presumptive reasoning for DL knowledge bases (also called DL ontologies) that may contain defeasible sentences. In particular, we present a plug-in for the Protégé ontology editor which implements these algorithms for OWL ontologies - the Web Ontology Language (OWL) is a formal standard of languages whose semantic basis is identical to that of DLs. Our plug-in, RaMP, allows the modeller to indicate defeasible information in OWL ontologies and perform logical inferencing to determine what defeasible conclusions one can draw from these ontologies.

@{58,
  author = {Kody Moodley and Tommie Meyer and Ivan Varzinczak},
  title = {A Defeasible Reasoning Approach for Description Logic Ontologies},
  abstract = {Classical reasoning for logic-based KR (Knowledge Representation) systems is in general, monotonic. That is, there is an assumption in these systems that there is complete information about a domain. This means that they generally cannot deal with any new information arising which contradicts with the current information. This is not an appropriate model for reasoning in many applications. Therefore, alternative non-monotonic systems have been investigated which can reason under uncertainty or with incomplete information. Defeasible reasoning is one particular model for implementing non-monotonic reasoning. It is concerned with representing and reasoning with defeasible (nonstrict) facts about a domain. The defeasible counterpart of the strict fact: “All birds fly” is the defeasible fact: “Most birds fly” (or the alternative phrasing “Birds usually fly”). We discuss two approaches for defeasible reasoning in the family of logicbased KR languages known as Description Logics (DLs). They are applicable to particular extensions of DLs that allow for the statement of defeasible sentences similar to the aforementioned examples. The 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 an extension of propositional logic. Here we recast their definitions in a DL context and define algorithms for prototypical and presumptive reasoning for DL knowledge bases (also called DL ontologies) that may contain defeasible sentences. In particular, we present a plug-in for the Protégé ontology editor which implements these algorithms for OWL ontologies - the Web Ontology Language (OWL) is a formal standard of languages whose semantic basis is identical to that of DLs. Our plug-in, RaMP, allows the modeller to indicate defeasible information in OWL ontologies and perform logical inferencing to determine what defeasible conclusions one can draw from these ontologies.},
  year = {2012},
  journal = {South African Institute for Computer Scientists and Information Technologists (SAICSIT)},
  pages = {69-78},
  isbn = {978-1-4503-1308-7},
}