Thodoros Topaloglou - Academia.edu (original) (raw)
Papers by Thodoros Topaloglou
Healthcare systems around the world are embracing the concept of evidence-based medicine, a syste... more Healthcare systems around the world are embracing the concept of evidence-based medicine, a system where decisions about the care are made based on health data derived from population samples, clinical processes, and personalized wearable devices. This information is potentially a promising source of new threads of knowledge for all healthcare stakeholders. The knowledge gained from data-intensive research directly impacts the advancement of eHealth, as better understanding of health and innovation leads to better delivery of healthcare.
Proceedings of the 10th international conference on Electronic commerce, 2008
The Internet and related technologies have created enormous potential for disruptive innovations.... more The Internet and related technologies have created enormous potential for disruptive innovations. Businesses engaging in ecommerce must constantly be examining opportunities and threats arising from disruptive change. Modeling techniques have been introduced to help visualize and reason about business models and strategies. This paper offers a modeling approach which characterizes a business model not in terms of flows or exchanges, but the strategic dependencies among various players. The business model is then analyzed in relation to the high-level strategy of the business. When a change arises, competitive scenarios are analyzed in terms of the strategic choices for the incumbent and new entrants. A historical case study from the telecom sector is used to illustrate.
Information Systems and e-Business Management, 2008
Strategic reasoning about business models is an integral part of service design. In fast moving m... more Strategic reasoning about business models is an integral part of service design. In fast moving markets, businesses must be able to recognize and respond strategically to disruptive change. They have to answer questions such as: what are the threats and opportunities in emerging technologies and innovations? How should they target customer groups? Who are their real competitors? How will competitive
Knowledge Building and Knowledge Sharing, 1994
The management of very large knowledge bases presupposes efficient and robust implementation tech... more The management of very large knowledge bases presupposes efficient and robust implementation techniques, sophisticated user interfaces and tools to support knowledge acquisition, validation and evolution. This paper examines the problem of efficiently implementing a knowledge base management system by adopting database techniques. In particular, the paper describes algorithms for designing logical and physical storage schemes and for processing efficiently queries with respect to a given knowledge ...
Advanced applications in elds such as CAD, Software Engineering, Real-Time Process Control, Corpo... more Advanced applications in elds such as CAD, Software Engineering, Real-Time Process Control, Corporate Repositories and Digital Libraries require the construction, e cient access and management of large, shared knowledge bases. Such knowledge bases cannot be built using existing tools such as expert system shells, because these do not scale up; nor can they be built in terms of existing database technology because such technology does not support the rich representational structure and inference mechanisms required ...
The VLDB Journal The International Journal on Very Large Data Bases, 1996
Advanced applications in fields such as CAD, software engineering, real-time process control, cor... more Advanced applications in fields such as CAD, software engineering, real-time process control, corporate repositories and digital libraries require the construction, efficient access and management of large, shared knowledge bases. Such knowledge bases cannot be built using existing tools such as expert system shells, because these do not scale up, nor can they be built in terms of existing database technology, because such technology does not support the rich representational structure and inference mechanisms required for knowledge-based systems. This paper proposes a generic architecture for a knowledge base management system intended for such applications. The architecture assumes an object-oriented knowledge representation language with an assertional sublanguage used to express constraints and rules. It also provides for general-purpose deductive inference and special-purpose temporal reasoning. Results reported in the paper address several knowledge base management issues. For storage management, a new method is proposed for generating a logical schema for a given knowledge base. Query processing algorithms are offered for semantic and physical query optimization, along with an enhanced cost model for query cost estimation. On concurrency control, the paper describes a novel concurrency control policy which takes advantage of knowledge base structure and is shown to outperform two-phase locking for highly structured knowledge bases and update-intensive transactions. Finally, algorithms for compilation and efficient processing of constraints and rules during knowledge base operations are described. The paper describes original results, including novel data structures and algorithms, as well as preliminary performance evaluation data. Based on these results, we conclude that knowledge base management systems which can accommodate large knowledge bases are feasible.
Existing query interfaces for biological databases are either based on fixed forms or textual que... more Existing query interfaces for biological databases are either based on fixed forms or textual query languages. Users of a fixed form-based query interface are lim-ited to performing some pre-defined queries providing a fixed view of the underlying database, while users of a free text query language-based interface have to under-stand the underlying data models, specific query lan-guages and application schemas in order to formulate queries. Further, operations on application-specific complex data (e.g., DNA sequences, proteins), which are usually provided by a variety of software packages with their own format requirements and peculiarities, are not available as part of, nor integrated with biolog-ical query interfaces. In this paper, we describe generic tools that provide powerful and flexible support for interactively explor-ing biological databases in a uniform and consistent way, that is via common data models, formats, and no-tations, in the framework of the Object-Protocol Mod...
Ontologies are specifications of the concepts in a given field, and of the relationships among th... more Ontologies are specifications of the concepts in a given field, and of the relationships among those concepts. The development of ontologies for molecular-biology information and the sharing of those ontologies within the bioinformatics community are central problems in bioinformatics. If the bioinformatics community is to share ontologies effectively, ontologies must be exchanged in a form that uses standardized syntax and semantics. This paper reports on an effort among the authors to evaluate alternative ontology-exchange languages, and to recommend one or more languages for use within the larger 1bioinformatics community. The study selected a set of candidate languages, and defined a set of capabilities that the ideal ontology-exchange language should satisfy. The
Organizations turn to technology as a possible solution to improve efficiency and reduce waste in... more Organizations turn to technology as a possible solution to improve efficiency and reduce waste in their operating processes. Most of their ineffi- ciencies and opportunities for improvement are hiding in their process level da- ta. This experience paper describes the information needs in a hospital setting and the journey of delivering a business intelligence program that was designed to address those needs. The core focus in our business intelligence work was to deliver relevant and actionable information to the front line staff to assist them in their work. There are two story lines in this experience paper. One is about the value of information and evidence in solving business problems. The second is about the information systems methods toolbox we utilized in establishing an effective business intelligence program in an operating organization. As budgets in the not-for-profit sector are under continuous pressure, organizations and governments turn to technology as a possible sol...
There are more than two hundred biological data repositories available for public access, and a v... more There are more than two hundred biological data repositories available for public access, and a vast number of applications to process and interpret biological data. A major challenge for bioinformaticians is to extract and process data from multiple data sources using a variety of query interfaces and analytical tools. In this paper, we describe tools that respond to this challenge by providing support for cross-database queries and for integrating analytical tools in a query processing environment. In particular, we describe two alternative methods for integrating biological data processing within traditional database queries: (a) "light-weight" application integration based on Application Specific Data Types (ASDTs) and (b) "heavy-duty" integration of analytical tools based on mediators and wrappers. These methods are supported by the Object-Protocol Model (OPM) suite of tools for managing biological databases.
This paper investigates the problem of reasoning about imprecise spatial information. As a repres... more This paper investigates the problem of reasoning about imprecise spatial information. As a representation scheme we assume haze-points that are points surrounded by an area, the haze, denoting the imprecision that is associated with them. Haze-points are related by haze and precedence relations. Using these notions we can build higher dimension objects and relations Top94a]. This paper focuses on reasoning about spatial imprecision which is formalized as a constraint satisfaction problem over networks of constraints expressed in the language of haze-orders. The main contributions of this paper are (a) a set of preprocessing transformations that decrease the ambiguity which is introduced from unconditional transitivity over the haze relation, and (b) a graph-based data structure which is suitable for ee-cient inferencing of order relations. 1 Introduction It is generally accepted that neither human perception nor measurement instruments are precise in the information they provide. Th...
Proceedings International Conference on Intelligent Systems For Molecular Biology Ismb International Conference on Intelligent Systems For Molecular Biology, Feb 1, 1998
Existing query interfaces for biological databases are either based on fixed forms or textual que... more Existing query interfaces for biological databases are either based on fixed forms or textual query languages. Users of a fixed form-based query interface are limited to performing some pre-defined queries providing a fixed view of the underlying database, while users of a free text query language-based interface have to understand the underlying data models, specific query languages and application schemas in order to formulate queries. Further, operations on application-specific complex data (e.g., DNA sequences, proteins), which are usually provided by a variety of software packages with their own format requirements and peculiarities, are not available as part of, nor integrated with biological query interfaces. In this paper, we describe generic tools that provide powerful and flexible support for interactively exploring biological databases in a uniform and consistent way, that is via common data models, formats, and notations, in the framework of the Object-Protocol Model (OPM). These tools include (i) a Java graphical query construction tool with support for automatic generation of Web query forms that can be either used for further specifying conditions, or can be saved and customized; (i.i) query processors for interpreting and executing queries that may involve complex applicationspecific objects, and that could span multiple heterogeneous databases and file systems; and (iii) utilities for automatic generation of HTML pages containing query results, that can be browsed using a Web browser. These tools avoid the restrictions imposed by traditional fixed-form query interfaces, while provid-Lag users with simple and intuitive facilities for formulating ad-hoc queries across heterogeneous databases, without the need to understand the underlying data models and query languages.
The paper proposes a novel spatial data model which facilitates the representation of and reasoni... more The paper proposes a novel spatial data model which facilitates the representation of and reasoning with various forms of qualitatively and quantitatively incomplete spatial information. The model is founded on a combination of object-oriented and constraint-based data modeling facilities and provides for representations of variable precision and granularity. The paper also identi es four basic reasoning tasks required for query processing operations and presents an algorithmic complexity assessment for each task.
In this paper we present a language for expressing \approximate" spatial relations on points... more In this paper we present a language for expressing \approximate" spatial relations on points and regions in space. Space is assumed to be two dimensional, orthogonal and discrete. Initially, we present a rst-order theory of one-dimensional approximate space. We axiomatize the theory of space in terms of points and the haze and precedence relations. We then study the models of this theory and we show that in the one dimensional case the theory has a unique model up to isomorphism. This result allows us to aarm that our theory is complete and decidable. Secondly, we propose a conservative two-dimensional extension of the theory which retains its completeness property. In the two-dimensional case, we deene a complete set of topolog-ical and directional relations that are useful for practical reasoning about space. The derived relations are related to existent formalisms for spatial relations such as Egen-hofer's 3-intersection model, for which they provide an alternative semantical account. The developed formalism is strictly qualitative with a built-in concept for imprecision. An axiomatization of varying the degree of detail is brieey discribed and discussed as a conclusion of the present work.
Procedia Computer Science, 2015
Abstract In this paper we propose a circle of care (COC) ontology that specifies concepts and rel... more Abstract In this paper we propose a circle of care (COC) ontology that specifies concepts and relations necessary to capture a patient's circle of care and allows one to make inferences about who is in a patient's circle of care. The ontology can improve current access control systems in making decisions regarding access events in real time and help identify past cases of illegitimate access through the access log. We validate the ontology by augmenting the Fast Healthcare Interoperability Resources (FHIR) data model with our COC ontology and presenting an example of access logs from FHIR that is extended to answer circle of care queries.
Healthcare systems around the world are embracing the concept of evidence-based medicine, a syste... more Healthcare systems around the world are embracing the concept of evidence-based medicine, a system where decisions about the care are made based on health data derived from population samples, clinical processes, and personalized wearable devices. This information is potentially a promising source of new threads of knowledge for all healthcare stakeholders. The knowledge gained from data-intensive research directly impacts the advancement of eHealth, as better understanding of health and innovation leads to better delivery of healthcare.
Proceedings of the 10th international conference on Electronic commerce, 2008
The Internet and related technologies have created enormous potential for disruptive innovations.... more The Internet and related technologies have created enormous potential for disruptive innovations. Businesses engaging in ecommerce must constantly be examining opportunities and threats arising from disruptive change. Modeling techniques have been introduced to help visualize and reason about business models and strategies. This paper offers a modeling approach which characterizes a business model not in terms of flows or exchanges, but the strategic dependencies among various players. The business model is then analyzed in relation to the high-level strategy of the business. When a change arises, competitive scenarios are analyzed in terms of the strategic choices for the incumbent and new entrants. A historical case study from the telecom sector is used to illustrate.
Information Systems and e-Business Management, 2008
Strategic reasoning about business models is an integral part of service design. In fast moving m... more Strategic reasoning about business models is an integral part of service design. In fast moving markets, businesses must be able to recognize and respond strategically to disruptive change. They have to answer questions such as: what are the threats and opportunities in emerging technologies and innovations? How should they target customer groups? Who are their real competitors? How will competitive
Knowledge Building and Knowledge Sharing, 1994
The management of very large knowledge bases presupposes efficient and robust implementation tech... more The management of very large knowledge bases presupposes efficient and robust implementation techniques, sophisticated user interfaces and tools to support knowledge acquisition, validation and evolution. This paper examines the problem of efficiently implementing a knowledge base management system by adopting database techniques. In particular, the paper describes algorithms for designing logical and physical storage schemes and for processing efficiently queries with respect to a given knowledge ...
Advanced applications in elds such as CAD, Software Engineering, Real-Time Process Control, Corpo... more Advanced applications in elds such as CAD, Software Engineering, Real-Time Process Control, Corporate Repositories and Digital Libraries require the construction, e cient access and management of large, shared knowledge bases. Such knowledge bases cannot be built using existing tools such as expert system shells, because these do not scale up; nor can they be built in terms of existing database technology because such technology does not support the rich representational structure and inference mechanisms required ...
The VLDB Journal The International Journal on Very Large Data Bases, 1996
Advanced applications in fields such as CAD, software engineering, real-time process control, cor... more Advanced applications in fields such as CAD, software engineering, real-time process control, corporate repositories and digital libraries require the construction, efficient access and management of large, shared knowledge bases. Such knowledge bases cannot be built using existing tools such as expert system shells, because these do not scale up, nor can they be built in terms of existing database technology, because such technology does not support the rich representational structure and inference mechanisms required for knowledge-based systems. This paper proposes a generic architecture for a knowledge base management system intended for such applications. The architecture assumes an object-oriented knowledge representation language with an assertional sublanguage used to express constraints and rules. It also provides for general-purpose deductive inference and special-purpose temporal reasoning. Results reported in the paper address several knowledge base management issues. For storage management, a new method is proposed for generating a logical schema for a given knowledge base. Query processing algorithms are offered for semantic and physical query optimization, along with an enhanced cost model for query cost estimation. On concurrency control, the paper describes a novel concurrency control policy which takes advantage of knowledge base structure and is shown to outperform two-phase locking for highly structured knowledge bases and update-intensive transactions. Finally, algorithms for compilation and efficient processing of constraints and rules during knowledge base operations are described. The paper describes original results, including novel data structures and algorithms, as well as preliminary performance evaluation data. Based on these results, we conclude that knowledge base management systems which can accommodate large knowledge bases are feasible.
Existing query interfaces for biological databases are either based on fixed forms or textual que... more Existing query interfaces for biological databases are either based on fixed forms or textual query languages. Users of a fixed form-based query interface are lim-ited to performing some pre-defined queries providing a fixed view of the underlying database, while users of a free text query language-based interface have to under-stand the underlying data models, specific query lan-guages and application schemas in order to formulate queries. Further, operations on application-specific complex data (e.g., DNA sequences, proteins), which are usually provided by a variety of software packages with their own format requirements and peculiarities, are not available as part of, nor integrated with biolog-ical query interfaces. In this paper, we describe generic tools that provide powerful and flexible support for interactively explor-ing biological databases in a uniform and consistent way, that is via common data models, formats, and no-tations, in the framework of the Object-Protocol Mod...
Ontologies are specifications of the concepts in a given field, and of the relationships among th... more Ontologies are specifications of the concepts in a given field, and of the relationships among those concepts. The development of ontologies for molecular-biology information and the sharing of those ontologies within the bioinformatics community are central problems in bioinformatics. If the bioinformatics community is to share ontologies effectively, ontologies must be exchanged in a form that uses standardized syntax and semantics. This paper reports on an effort among the authors to evaluate alternative ontology-exchange languages, and to recommend one or more languages for use within the larger 1bioinformatics community. The study selected a set of candidate languages, and defined a set of capabilities that the ideal ontology-exchange language should satisfy. The
Organizations turn to technology as a possible solution to improve efficiency and reduce waste in... more Organizations turn to technology as a possible solution to improve efficiency and reduce waste in their operating processes. Most of their ineffi- ciencies and opportunities for improvement are hiding in their process level da- ta. This experience paper describes the information needs in a hospital setting and the journey of delivering a business intelligence program that was designed to address those needs. The core focus in our business intelligence work was to deliver relevant and actionable information to the front line staff to assist them in their work. There are two story lines in this experience paper. One is about the value of information and evidence in solving business problems. The second is about the information systems methods toolbox we utilized in establishing an effective business intelligence program in an operating organization. As budgets in the not-for-profit sector are under continuous pressure, organizations and governments turn to technology as a possible sol...
There are more than two hundred biological data repositories available for public access, and a v... more There are more than two hundred biological data repositories available for public access, and a vast number of applications to process and interpret biological data. A major challenge for bioinformaticians is to extract and process data from multiple data sources using a variety of query interfaces and analytical tools. In this paper, we describe tools that respond to this challenge by providing support for cross-database queries and for integrating analytical tools in a query processing environment. In particular, we describe two alternative methods for integrating biological data processing within traditional database queries: (a) "light-weight" application integration based on Application Specific Data Types (ASDTs) and (b) "heavy-duty" integration of analytical tools based on mediators and wrappers. These methods are supported by the Object-Protocol Model (OPM) suite of tools for managing biological databases.
This paper investigates the problem of reasoning about imprecise spatial information. As a repres... more This paper investigates the problem of reasoning about imprecise spatial information. As a representation scheme we assume haze-points that are points surrounded by an area, the haze, denoting the imprecision that is associated with them. Haze-points are related by haze and precedence relations. Using these notions we can build higher dimension objects and relations Top94a]. This paper focuses on reasoning about spatial imprecision which is formalized as a constraint satisfaction problem over networks of constraints expressed in the language of haze-orders. The main contributions of this paper are (a) a set of preprocessing transformations that decrease the ambiguity which is introduced from unconditional transitivity over the haze relation, and (b) a graph-based data structure which is suitable for ee-cient inferencing of order relations. 1 Introduction It is generally accepted that neither human perception nor measurement instruments are precise in the information they provide. Th...
Proceedings International Conference on Intelligent Systems For Molecular Biology Ismb International Conference on Intelligent Systems For Molecular Biology, Feb 1, 1998
Existing query interfaces for biological databases are either based on fixed forms or textual que... more Existing query interfaces for biological databases are either based on fixed forms or textual query languages. Users of a fixed form-based query interface are limited to performing some pre-defined queries providing a fixed view of the underlying database, while users of a free text query language-based interface have to understand the underlying data models, specific query languages and application schemas in order to formulate queries. Further, operations on application-specific complex data (e.g., DNA sequences, proteins), which are usually provided by a variety of software packages with their own format requirements and peculiarities, are not available as part of, nor integrated with biological query interfaces. In this paper, we describe generic tools that provide powerful and flexible support for interactively exploring biological databases in a uniform and consistent way, that is via common data models, formats, and notations, in the framework of the Object-Protocol Model (OPM). These tools include (i) a Java graphical query construction tool with support for automatic generation of Web query forms that can be either used for further specifying conditions, or can be saved and customized; (i.i) query processors for interpreting and executing queries that may involve complex applicationspecific objects, and that could span multiple heterogeneous databases and file systems; and (iii) utilities for automatic generation of HTML pages containing query results, that can be browsed using a Web browser. These tools avoid the restrictions imposed by traditional fixed-form query interfaces, while provid-Lag users with simple and intuitive facilities for formulating ad-hoc queries across heterogeneous databases, without the need to understand the underlying data models and query languages.
The paper proposes a novel spatial data model which facilitates the representation of and reasoni... more The paper proposes a novel spatial data model which facilitates the representation of and reasoning with various forms of qualitatively and quantitatively incomplete spatial information. The model is founded on a combination of object-oriented and constraint-based data modeling facilities and provides for representations of variable precision and granularity. The paper also identi es four basic reasoning tasks required for query processing operations and presents an algorithmic complexity assessment for each task.
In this paper we present a language for expressing \approximate" spatial relations on points... more In this paper we present a language for expressing \approximate" spatial relations on points and regions in space. Space is assumed to be two dimensional, orthogonal and discrete. Initially, we present a rst-order theory of one-dimensional approximate space. We axiomatize the theory of space in terms of points and the haze and precedence relations. We then study the models of this theory and we show that in the one dimensional case the theory has a unique model up to isomorphism. This result allows us to aarm that our theory is complete and decidable. Secondly, we propose a conservative two-dimensional extension of the theory which retains its completeness property. In the two-dimensional case, we deene a complete set of topolog-ical and directional relations that are useful for practical reasoning about space. The derived relations are related to existent formalisms for spatial relations such as Egen-hofer's 3-intersection model, for which they provide an alternative semantical account. The developed formalism is strictly qualitative with a built-in concept for imprecision. An axiomatization of varying the degree of detail is brieey discribed and discussed as a conclusion of the present work.
Procedia Computer Science, 2015
Abstract In this paper we propose a circle of care (COC) ontology that specifies concepts and rel... more Abstract In this paper we propose a circle of care (COC) ontology that specifies concepts and relations necessary to capture a patient's circle of care and allows one to make inferences about who is in a patient's circle of care. The ontology can improve current access control systems in making decisions regarding access events in real time and help identify past cases of illegitimate access through the access log. We validate the ontology by augmenting the Fast Healthcare Interoperability Resources (FHIR) data model with our COC ontology and presenting an example of access logs from FHIR that is extended to answer circle of care queries.