http://sedici.unlp.edu.ar:80/handle/10915/134629 Thu, 12 Nov 2026 10:42:33 GMT 2026-11-12T10:42:33Z http://sedici.unlp.edu.ar:80/handle/10915/135497 Contribucion a revista Electronic Journal of SADIO; vol. 3 Geographic information systems (GIS) deal with data which can potentially be useful for a wide range of applications. However, the information needs of each application usually vary, specially in resolution, detail level, and representation style. This thesis presents a set of primitives that allow the specification of operational processes, such as transformations between representations, through the use of a dynamic schema. Mon, 26 Jun 2000 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/135497 2000-06-26T00:00:00Z Geographic information systems (GIS) deal with data which can potentially be useful for a wide range of applications. However, the information needs of each application usually vary, specially in resolution, detail level, and representation style. This thesis presents a set of primitives that allow the specification of operational processes, such as transformations between representations, through the use of a dynamic schema. http://sedici.unlp.edu.ar:80/handle/10915/135490 Articulo Electronic Journal of SADIO; vol. 3 Rossi, Gustavo Héctor This research is aimed at defining and discussing a quantitative methodology, the one integral, robust and flexible, for the quality evaluation and comparison of Web sites and applications (WebApps). The approach, from now on called Web-site Quality Evaluation Methodology (Web-site QEM) is intended to perform an engineering contribution proposing for such an end a systematic, disciplined and quantitative strategy customized to the evaluation, comparison, and analysis of the quality of somewhat complex WebApps. We analyze their phases and activities, we describe the produced deliverables, and we present models, methods, procedures, principles and tools to apply in these activities. We outline the approach and its solutions, using along the thesis two case studies for WebApps, and other carried out field studies. In addition, we present a conceptual framework for metric validation and we discuss the theoretical validation of some utilized metrics in the evaluation process. Finally, we describe thoroughly an evaluation process model which Web-site QEM adheres. In this report, just the main methodology’s steps are shown. Besides, some specific models, criteria and procedures to apply in these activities are discussed by quoting case studies already performed (e.g., in the academic domain as well as in museums and e-commerce domain, i.e., international e-bookstores ). Mon, 26 Jun 2000 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/135490 2000-06-26T00:00:00Z This research is aimed at defining and discussing a quantitative methodology, the one integral, robust and flexible, for the quality evaluation and comparison of Web sites and applications (WebApps). The approach, from now on called Web-site Quality Evaluation Methodology (Web-site QEM) is intended to perform an engineering contribution proposing for such an end a systematic, disciplined and quantitative strategy customized to the evaluation, comparison, and analysis of the quality of somewhat complex WebApps. We analyze their phases and activities, we describe the produced deliverables, and we present models, methods, procedures, principles and tools to apply in these activities. We outline the approach and its solutions, using along the thesis two case studies for WebApps, and other carried out field studies. In addition, we present a conceptual framework for metric validation and we discuss the theoretical validation of some utilized metrics in the evaluation process. Finally, we describe thoroughly an evaluation process model which Web-site QEM adheres. In this report, just the main methodology’s steps are shown. Besides, some specific models, criteria and procedures to apply in these activities are discussed by quoting case studies already performed (e.g., in the academic domain as well as in museums and e-commerce domain, i.e., international e-bookstores ). http://sedici.unlp.edu.ar:80/handle/10915/135478 Contribucion a revista Electronic Journal of SADIO; vol. 3 The main objective of this thesis is to propose a categorizing model for medical documents,called HiMeD Model. The HiMeD Model is based on the principle that we denominatedhierarchical correlation of specialized terms, in which a medical concept, to be used in anautomatic categorization process, can always be represented by terms, where these termsare linked up in a hierarchical path. This hierarchical linking can contain components thatallow the determination of these categories ordered by the degree of relevance of theadopted concept. The use of this principle allows us to isolate the categorization tasks fromthe unnecessary influence of terms not belonging to the medical vocabulary of referenceand of the straight calculation of the term-weight in the information retrieval process usedby the classic models. The concepts developed here were used in several experiments thatdemonstrated the quality of the proposed model. These experiments are another importantcontribution of this work. Finally, a tool for automatic coding of medical documents wasimplemented based on the components of our model, thus demonstrating its technologicalcapacity in building automatic categorization tools. This tool, called MedCode, was used inexperiments carried out with the help of medical coding specialists, and its use improvedthe precision of the automatic coding of medical documents. This improvement is largelydue to the interactive and visual characteristics of the prototype, which allowed thespecialists to modify the coding environment, to select the type of processing algorithm,and to modify other document processing options. Mon, 26 Jun 2000 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/135478 2000-06-26T00:00:00Z The main objective of this thesis is to propose a categorizing model for medical documents,called HiMeD Model. The HiMeD Model is based on the principle that we denominatedhierarchical correlation of specialized terms, in which a medical concept, to be used in anautomatic categorization process, can always be represented by terms, where these termsare linked up in a hierarchical path. This hierarchical linking can contain components thatallow the determination of these categories ordered by the degree of relevance of theadopted concept. The use of this principle allows us to isolate the categorization tasks fromthe unnecessary influence of terms not belonging to the medical vocabulary of referenceand of the straight calculation of the term-weight in the information retrieval process usedby the classic models. The concepts developed here were used in several experiments thatdemonstrated the quality of the proposed model. These experiments are another importantcontribution of this work. Finally, a tool for automatic coding of medical documents wasimplemented based on the components of our model, thus demonstrating its technologicalcapacity in building automatic categorization tools. This tool, called MedCode, was used inexperiments carried out with the help of medical coding specialists, and its use improvedthe precision of the automatic coding of medical documents. This improvement is largelydue to the interactive and visual characteristics of the prototype, which allowed thespecialists to modify the coding environment, to select the type of processing algorithm,and to modify other document processing options. http://sedici.unlp.edu.ar:80/handle/10915/135471 Contribucion a revista Electronic Journal of SADIO; vol. 3 Circular-arc graphs are the intersection graphs of arcs on a circle. We review in this thesis the main results known about this class and we analize some subclasses of it. We show new characterizations for proper circular-arc graphs derived from a characterization formulated by Tucker, and we deduce minimal forbidden structures for circular arc-graphs.All possible intersections of the defined subclasses are studied, showing a minimal example in each one of the generated regions, except one of them that we prove it is empty. From here, we conclude that a clique-Helly and proper no unit circular-arc graph must be Hellycircular-arc graph.Circle graphs are the intersection graphs of chords in a circle. We present also a review of the main results in this class and define the most important subclasses, proving some relations of inclusions between them.We prove a neccesary condition so that a graph is a Helly circle graph and conjecture thatthis condition is sufficient too. If this conjecture becomes true, we would have acharacterization and a polynomial recognition for this subclass.Minimal forbidden structures for circle graphs are shown, using the chacterization of propercircular-arc graphs by Tucker and a characterization theorem for circle graphs by Bouchet.We also analize all the possible intersections between the defined subclasses of circlegraphs, showing a minimal example in each generated region.A superclass of circle graphs is studied: overlap graphs of circular-arc graphs. We show new properties on this class, analizing its relation with circle and circular-arc graphs. A necessary condition for a graph being an overlap graph of circular-arc graphs is shown. We prove that the problem of finding a minimum clique partition for the class of graphs which does not contain either odd holes, or a 3-fan, or a 4-wheel as induced subgraphs, can be solved in polynomial time. We use in the proof results of polyhedral theory for integer linear programming. We extend this result for minimum clique covering by vertices. These results are applied for Helly circle graphs without odd holes. We also show that the problem of minimum clique covering by vertices can be solved in polynomial time for Helly circular-arc graphs. Finally, we present some interesting problems which remain open. Mon, 26 Jun 2000 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/135471 2000-06-26T00:00:00Z Circular-arc graphs are the intersection graphs of arcs on a circle. We review in this thesis the main results known about this class and we analize some subclasses of it. We show new characterizations for proper circular-arc graphs derived from a characterization formulated by Tucker, and we deduce minimal forbidden structures for circular arc-graphs.All possible intersections of the defined subclasses are studied, showing a minimal example in each one of the generated regions, except one of them that we prove it is empty. From here, we conclude that a clique-Helly and proper no unit circular-arc graph must be Hellycircular-arc graph.Circle graphs are the intersection graphs of chords in a circle. We present also a review of the main results in this class and define the most important subclasses, proving some relations of inclusions between them.We prove a neccesary condition so that a graph is a Helly circle graph and conjecture thatthis condition is sufficient too. If this conjecture becomes true, we would have acharacterization and a polynomial recognition for this subclass.Minimal forbidden structures for circle graphs are shown, using the chacterization of propercircular-arc graphs by Tucker and a characterization theorem for circle graphs by Bouchet.We also analize all the possible intersections between the defined subclasses of circlegraphs, showing a minimal example in each generated region.A superclass of circle graphs is studied: overlap graphs of circular-arc graphs. We show new properties on this class, analizing its relation with circle and circular-arc graphs. A necessary condition for a graph being an overlap graph of circular-arc graphs is shown. We prove that the problem of finding a minimum clique partition for the class of graphs which does not contain either odd holes, or a 3-fan, or a 4-wheel as induced subgraphs, can be solved in polynomial time. We use in the proof results of polyhedral theory for integer linear programming. We extend this result for minimum clique covering by vertices. These results are applied for Helly circle graphs without odd holes. We also show that the problem of minimum clique covering by vertices can be solved in polynomial time for Helly circular-arc graphs. Finally, we present some interesting problems which remain open. http://sedici.unlp.edu.ar:80/handle/10915/135464 Articulo Electronic Journal of SADIO; vol. 3 The underlying concept in Reinforcement Learning is as simple as it is attractive: to learn by trial and error from the interaction with the environment. This approach allows us to deal with problems where a learning technique searches to improve the performance of the agent (the learner) over time. Reinforcement Learning groups a set of such techniques, and it uses a performance measure based on two types of signals given by a Critic or Reinforcement Function: penalty and reward. Mon, 26 Jun 2000 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/135464 2000-06-26T00:00:00Z The underlying concept in Reinforcement Learning is as simple as it is attractive: to learn by trial and error from the interaction with the environment. This approach allows us to deal with problems where a learning technique searches to improve the performance of the agent (the learner) over time. Reinforcement Learning groups a set of such techniques, and it uses a performance measure based on two types of signals given by a Critic or Reinforcement Function: penalty and reward. http://sedici.unlp.edu.ar:80/handle/10915/135461 Contribucion a revista Electronic Journal of SADIO; vol. 3 The problem of change in corpora of information is indeed interesting. Legislation is under constant modification, new discoveries reshape scientific theories and robots have to update their representation of the world each time a sensor gains new data. The theory of theory change oers a model for these processes under certain idealizations. Mon, 26 Jun 2000 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/135461 2000-06-26T00:00:00Z The problem of change in corpora of information is indeed interesting. Legislation is under constant modification, new discoveries reshape scientific theories and robots have to update their representation of the world each time a sensor gains new data. The theory of theory change oers a model for these processes under certain idealizations. http://sedici.unlp.edu.ar:80/handle/10915/135456 Contribucion a revista Electronic Journal of SADIO; vol. 3 It is widely recognized that public-key cryptography is an important tool for providing security services such as condentiality, data integrity, authentication and non-repudiation, which are requirements present in almost all communications. The main advantage of elliptic curve cryptography (ECC) over competing public-key technologies such as RSA and DSA, is that signicantly smaller parameters can be used in ECC, but with equivalent levels of security. This advantage is especially important for applications on constrained environments such as smart cards, cell phones, personal device assistants, and pagers.From a practical point of view, the implementation of ECC presents various challenges. An ECC-based application requires that several choices be made including the security level, algorithms for implementing the nite eld arithmetic, algorithms for implementing the elliptic group operation, elliptic curve protocols, and the computer platform. These choices may have a signicant impact on the performance of the resulting application.This dissertation focuses on developing ecient algorithms for software implementation of ECC over F 2m. In this framework, we study dierent ways of eciently implementing arithmetic in F 2m, and computing an elliptic scalar multiplication, the central operation of public-key cryptography based on elliptic curves. We also concentrate on the software implementation of these algorithms for diferent platforms including PCs, workstations, and constrained devices such as the RIM interactive pager.This dissertation is a collection of ve papers written in English, with an introduction and conclusions written in Portuguese. Mon, 26 Jun 2000 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/135456 2000-06-26T00:00:00Z It is widely recognized that public-key cryptography is an important tool for providing security services such as condentiality, data integrity, authentication and non-repudiation, which are requirements present in almost all communications. The main advantage of elliptic curve cryptography (ECC) over competing public-key technologies such as RSA and DSA, is that signicantly smaller parameters can be used in ECC, but with equivalent levels of security. This advantage is especially important for applications on constrained environments such as smart cards, cell phones, personal device assistants, and pagers.From a practical point of view, the implementation of ECC presents various challenges. An ECC-based application requires that several choices be made including the security level, algorithms for implementing the nite eld arithmetic, algorithms for implementing the elliptic group operation, elliptic curve protocols, and the computer platform. These choices may have a signicant impact on the performance of the resulting application.This dissertation focuses on developing ecient algorithms for software implementation of ECC over F 2m. In this framework, we study dierent ways of eciently implementing arithmetic in F 2m, and computing an elliptic scalar multiplication, the central operation of public-key cryptography based on elliptic curves. We also concentrate on the software implementation of these algorithms for diferent platforms including PCs, workstations, and constrained devices such as the RIM interactive pager.This dissertation is a collection of ve papers written in English, with an introduction and conclusions written in Portuguese. http://sedici.unlp.edu.ar:80/handle/10915/135447 Articulo Electronic Journal of SADIO; vol. 3 In this paper we describe Wf-ATOMS, a framework for the specification and management of workflows, whose engine is integrated in a multi user and distributed task management system. The process models include features standard in other workflow management systems, concerning the form in which the activities forming the processes interact, and other features usually managed by user-task management systems that model the different activities available in interactive applications. The conjunction of these two models provides several benefits. On one hand, there is a simplification in the development of workflow-based applications. On the other hand, it allows the systematic development of training applications for work teams that collaborate in the accomplishment of distributed processes. In this paper we describe both the framework from the point of view of the specification of distributed processes and the underlying architecture of the process management system. Wf-ATOMS has been developed as an extension of ATOMS, a previous framework for the management of user tasks in interactive applications. Mon, 26 Jun 2000 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/135447 2000-06-26T00:00:00Z In this paper we describe Wf-ATOMS, a framework for the specification and management of workflows, whose engine is integrated in a multi user and distributed task management system. The process models include features standard in other workflow management systems, concerning the form in which the activities forming the processes interact, and other features usually managed by user-task management systems that model the different activities available in interactive applications. The conjunction of these two models provides several benefits. On one hand, there is a simplification in the development of workflow-based applications. On the other hand, it allows the systematic development of training applications for work teams that collaborate in the accomplishment of distributed processes. In this paper we describe both the framework from the point of view of the specification of distributed processes and the underlying architecture of the process management system. Wf-ATOMS has been developed as an extension of ATOMS, a previous framework for the management of user tasks in interactive applications. http://sedici.unlp.edu.ar:80/handle/10915/135421 Articulo Electronic Journal of SADIO; vol. 3 The complexity of distributed systems (multi-agent systems in particular) involves the design and coordination of many entities (called agents). This activity is not trivial and there is not a standard way to do this. So, it is desirable to have tools for reusing previous designed components and relations between them. Frameworks allow design and code to be reused. Intelligent agents cover a big amount of application domains but we can detect an important set of common characteristics that can be abstracted for reusing. This paper presents a framework for multi-agent systems (FraMaS) composed by these common characteristics. FraMaS is used to design agents that have capabilities for perceiving environment, communicating, and deliberating about what to do next. Mon, 26 Jun 2000 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/135421 2000-06-26T00:00:00Z The complexity of distributed systems (multi-agent systems in particular) involves the design and coordination of many entities (called agents). This activity is not trivial and there is not a standard way to do this. So, it is desirable to have tools for reusing previous designed components and relations between them. Frameworks allow design and code to be reused. Intelligent agents cover a big amount of application domains but we can detect an important set of common characteristics that can be abstracted for reusing. This paper presents a framework for multi-agent systems (FraMaS) composed by these common characteristics. FraMaS is used to design agents that have capabilities for perceiving environment, communicating, and deliberating about what to do next. http://sedici.unlp.edu.ar:80/handle/10915/135419 Articulo Electronic Journal of SADIO; vol. 3 Real-time systems are found in an increasing variety of application elds. Usually, they are embedded systems controlling devices that may risk lives or damage properties: they are safety critical systems. Hard Real-Time requirements (late means wrong) make the development of such kind of systems a formidable and daunting task.The need to predict temporal behavior of critical real-time systems has encouraged the development of an useful collection of models, results and tools for analyzing schedulability of applications. However, there is no general analytical support for verifying other kind of high level timing requirements on complex software architectures. On the other hand, the verication of specications and designs of real-time systems has been considered an interesting application eld for automatic analysis techniques such as model-checking. Unfortunately, there is a natural trade-o between sophistication of supported features and the practicality of formal analysis. Mon, 26 Jun 2000 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/135419 2000-06-26T00:00:00Z Real-time systems are found in an increasing variety of application elds. Usually, they are embedded systems controlling devices that may risk lives or damage properties: they are safety critical systems. Hard Real-Time requirements (late means wrong) make the development of such kind of systems a formidable and daunting task.The need to predict temporal behavior of critical real-time systems has encouraged the development of an useful collection of models, results and tools for analyzing schedulability of applications. However, there is no general analytical support for verifying other kind of high level timing requirements on complex software architectures. On the other hand, the verication of specications and designs of real-time systems has been considered an interesting application eld for automatic analysis techniques such as model-checking. Unfortunately, there is a natural trade-o between sophistication of supported features and the practicality of formal analysis. http://sedici.unlp.edu.ar:80/handle/10915/135412 Articulo Electronic Journal of SADIO; vol. 3 This paper describes the object-oriented features of TANGOW (Task-based Adaptive learNer Guidance On the WWW), a tool for developing Internet-based courses. This system facilitates the construction of adaptive learning environments for the WWW and is able to guide the students during their learning process based on student profiles and previous actions. In the TANGOW system, the course contents is modelled in terms of objects and relationships among them. This allows the course designer to reuse the same descriptive objects in different sections of the same course, or even in completely different courses. In addition, information about the student and his/her actions when interacting with the system is also stored as dynamic objects, which are instantiated at runtime. This makes it easy to access and update student related data. Mon, 26 Jun 2000 00:00:00 GMT http://sedici.unlp.edu.ar:80/handle/10915/135412 2000-06-26T00:00:00Z This paper describes the object-oriented features of TANGOW (Task-based Adaptive learNer Guidance On the WWW), a tool for developing Internet-based courses. This system facilitates the construction of adaptive learning environments for the WWW and is able to guide the students during their learning process based on student profiles and previous actions. In the TANGOW system, the course contents is modelled in terms of objects and relationships among them. This allows the course designer to reuse the same descriptive objects in different sections of the same course, or even in completely different courses. In addition, information about the student and his/her actions when interacting with the system is also stored as dynamic objects, which are instantiated at runtime. This makes it easy to access and update student related data.