Proceedings of the 14th Brazilian Symposium on Human Factors in Computing Systems, 2015
The major challenge for usability tests on mobile systems is to reproduce the context in which th... more The major challenge for usability tests on mobile systems is to reproduce the context in which they are used. This paper points out some of the main difficulties encountered in the evaluation of such mobile systems, considering the real context of the user. Considering the need to assess such applications on the user's context, it was conducted a field study to evaluate an urban mobility system and, for this purpose, it was proposed a collection instrument, which can be used by the observer to take notes related to the evaluation, enabling various forms of content (observations, important points of the environment, user's verbal utterances, etc.). Through the field study, it was evaluated the benefits of using the proposed instrument, as well as identifying some of the difficulties faced in this type of study, i.e., evaluation of mobile systems on the move.
adaptive agents and multi-agents systems, May 9, 2016
Argumentation-based reasoning plays an important role in agent reasoning and communication. In th... more Argumentation-based reasoning plays an important role in agent reasoning and communication. In this work, we extend an argumentation-based reasoning mechanism to take into account preferences over arguments supporting contrary conclusions. Such preferences come from elements that are present or can be more easily obtained in the context of practical multi-agent programming platforms, such as multiple sources from which the information (used to construct the arguments) was acquired, as well as varying degrees of trust on them. Further, we introduce different agent profiles by varying the way certain operators are applied over the various information sources. Unlike previous approaches, our approach accounts for multiple sources for a single piece of information and is based on an argumentation-based reasoning mechanism implemented on a multi-agent platform.
Bed allocation in hospitals is a critical and important problem, and it has become even more impo... more Bed allocation in hospitals is a critical and important problem, and it has become even more important since last year because of the COVID-19 pandemic. In this paper, we present an approach based on intelligent-agent technologies to assist hospital staff in charge of bed allocation. As part of this work, we developed a web-based simulation of a hospital bed allocation system integrated with a chatbot for interaction with the user. As a core component in our approach, an intelligent agent uses the feedback of a plan validator to check if there are any flaws in a user-made allocation, communicating any detected problems to the user using natural language through the chatbot. Thus, our resulting application not only validates bed allocation plans but also interacts with hospital professionals using natural language communication, including giving explainable suggestions of better alternative allocations. We evaluated our approach with professionals responsible for bed allocation in two local hospitals and a doctor who provides consultancy to another local hospital. The version of the system reported in this paper addresses all the suggestions made by the specialists who evaluated its previous version.
2018 7th Brazilian Conference on Intelligent Systems (BRACIS), 2018
The theory of argumentation spans several fields of knowledge, gaining significant space in the c... more The theory of argumentation spans several fields of knowledge, gaining significant space in the community of multiagent systems because it gives support for agents to reason about uncertain beliefs. This work describes the development of an argumentation-based inference architecture for BDI agents, which was developed based on Toulmin's model of argumentation. The philosopher Stephen Toulmin claimed that arguments typically consist of six parts: data, warrants, claim, backing, qualifiers, and rebuttals. Using the proposed architecture, an agent is able to create new beliefs based on available evidence and to justify such beliefs.
Argumentation appears in two main Unes of research in the íield of multi-agent systems: argumenta... more Argumentation appears in two main Unes of research in the íield of multi-agent systems: argumentation-based reasoning and argumentation-based dialogues. In this document we present an approach exploring both of those Unes of research. First, we develop an argumentation-based reasoning mechanism in an agent-oriented programming language based on the BDI architecture. This reasoning mechanism is based on a defeasible logic formalism and the notion of defeasible semantics. Using that argumentation-based reasoning mechanism, agents can reason under uncertainty and can use arguments to supports their claims when engaging in multi-agent dialogues. Second, we give operational semantics to a set of speech acts found in the literature on argumentation-based dialogues. That semantics is also given in the context of BDI-inspired agentoriented programming languages. Next, we define a protocol for argumentation-based dialogues for task reallocation, using the reasoning mechanism and the operatio...
In this work, we use meta-information to help an agents reasoning when it has conflicting informa... more In this work, we use meta-information to help an agents reasoning when it has conflicting information. One such criteria is trust, a well-known concept used to allow an agent to set a trust value on a belief, according to the trust value of its sources. This way, an agent can have a kind of priority about conflicting information, according to its trust value. Then, we use another criteria, to allow the agent to consider not only the source of a belief, but the information about how recent it is. This way, the trust value of a belief will vary over time, allowing the agent to prior the older or most recent beliefs acquired, according to the needs of the application. Finally, we define some agent profiles in regards to how they aggregate the conflicting sources, and we present an example scenario where the proposed criteria are used by agents. Resumo. Neste trabalho são utilizadas metainformações a fim de auxiliar um agente a tomar uma decisão quando este recebe informações conflitant...
Recently, argumentation frameworks have been extended in order to consider trust when defining pr... more Recently, argumentation frameworks have been extended in order to consider trust when defining preferences between arguments, given that arguments (or information that supports the arguments) from more trustworthy sources may be preferred to arguments from less trustworthy sources. Although such literature presents interesting results on argumentation-based reasoning and how agents define preferences between arguments, there is little work taking into account agent strategies for argumentation-based dialogues using such information. In this work, we propose an argumentation framework in which agents consider how much the recipient of an argument trusts others in order to choose the most suitable argument for that particular recipient, i.e., arguments constructed using information from those sources that the recipient trusts. Our approach aims to allow agents to construct more effective arguments, depending on the recipients and on their views on the trustworthiness of potential sour...
No Brasil, a area de direito tributario tem enfrentado serios problemas devido ao atual modelo de... more No Brasil, a area de direito tributario tem enfrentado serios problemas devido ao atual modelo de aplicacao da lei no pais. Os casos de aplicacao da lei tributaria, em particular, tem uma grande parcela de responsabilidade pelas altas taxas de congestionamento judicial. O grande volume de acoes judiciais vencidas dificulta a eficacia da justica. Um dos pontos identificados como gargalo para a conclusao de tais processos legais, mais especificamente nos processos fiscais relacionados ao imposto municipal, e a identificacao dos Avisos de Recebimento (AR) que comprovam que os devedores receberam informacoes sobre as dividas que devem. Somente quando os tribunais estao na posse de um AR devidamente assinado, o processo pode avancar; quando uma entrega de aviso falhou, e necessario tentar novamente a entrega do aviso de divida e, de fato, pode ser necessario encontrar meios alternativos de entrar em contato com o devedor. Para ajudar a acelerar a resolucao de tais processos, estao sendo ...
Operational semantics is a fundamental approach to the formalisation of programming languages and... more Operational semantics is a fundamental approach to the formalisation of programming languages and almost a standard when it comes to agent-oriented programming languages. It helps ensure the correctness of interpreters, facilitates their implementation, and supports proofs of important properties. Multi-agent oriented systems are a particular kind of distributed systems and through the semantics of agent languages, operational semantics ended up playing an important role towards ensuring their desired behaviour, even though the operational semantics becomes more involved than originally intended. This work presents a new style for the operational semantics of systems with multiple levels of abstractions (such as multi-agent systems), by providing multi-level transitions (i.e., multiple hierarchical transition systems) with vertical (i.e., inter-level) integrity constraints to ensure consistency of interrelated transitions.
One of the main challenges in integrating different smart applications is security. Among the pro... more One of the main challenges in integrating different smart applications is security. Among the problems related to security, data access control is one of the most important, given that it involves end-users’ privacy. In this paper, we propose an approach to the modelling of data access control interfaces using argumentationbased agents. In particular, we introduce argumentation schemes for data access control, which are based on some of the most relevant models for data access control currently available. Our approach considers not only the usual access control policies, describing which category of agents has access to which category of information, but also emergency policies, describing situations where special emergency access control rules apply. Using argumentation-based agents as access control interfaces allows us to deal with the uncertainty about external information, allowing a correct categorisation of agents that request access to information, as well as allowing agents...
iSys - Brazilian Journal of Information Systems, 2017
In this work we compile our research regarding meta-information in multi-agent systems. In partic... more In this work we compile our research regarding meta-information in multi-agent systems. In particular, we describe some agents profiles represent- ing different attitudes which describe how agents consider meta-information in their decisions-making and reasoning processes. Furthermore, we describe how we have combined different meta-information available in multi-agent systems with an argumentation-based reasoning mechanism. In our approach, agents are able to decide more conflicts between information/arguments, given that they are able to use different meta-information (often combined) to decide between such conflicting information. Our framework for meta-information in multi- agent systems was implemented based on a modular architecture, thus other meta-information can be added, as well as different meta-information can be combined in order to create new agents profiles. Therefore, in our approach, different agents profiles can be instantiated for different application domains, al...
Several advantages can be obtained by allowing multi-agent systems to easily access ontologies, f... more Several advantages can be obtained by allowing multi-agent systems to easily access ontologies, for example, in scenarios where agents make their decisions based on knowledge provided by ontologies. Thus, this paper presents an infrastructure to allow the use of web ontologies in different agent-oriented platforms. The agents use this infrastructure layer as a tool for storing, accessing and querying domain-specific OWL ontologies. As a result, this layer allows an integration of agent platforms with semantic web data and ontologies. We exemplify in practice how agents, coded in one such platform, can use the proposed access layer to ontological reasoning engines, as well as which features can be obtained from it. We evaluated and compared performance and memory consumption of this semantic infrastructure against usual knowledge representation in agent programming.
International Journal of Engineering Research and Science, 2017
In this work, we propose a face recognition library, with the objective of lowering the implement... more In this work, we propose a face recognition library, with the objective of lowering the implementation complexity of face recognition features on applications in general. The library is based on Convolutional Neural Networks; a special kind of Neural Network specialized for image data. We present the main motivations for the use of face recognition, as well as the main interface for using the library features. We describe the overall architecture structure of the library and evaluated it on a large scale scenario. The proposed library achieved an accuracy of 98.14% when using a required confidence of 90%, and an accuracy of 99.86% otherwise.
2016 5th Brazilian Conference on Intelligent Systems (BRACIS), 2016
Argumentation in multi-agent systems provides both a mechanism for agent reasoning under uncertai... more Argumentation in multi-agent systems provides both a mechanism for agent reasoning under uncertainty and conflicting information as well as for communication in a more elaborate way, allowing agents to understand each other through the exchange of additional information when compared to other forms of agent communication. Even though argumentation techniques can play an important role in multi-agent systems, little research has been carried out on the issues in integrating argumentation techniques and agent-oriented programming languages, which would allow the development of practical applications taking advantage of such combined techniques. In this work, we present an argumentation framework developed on the basis of an agent-oriented programming language. We cover mainly the practical aspects of such integration, focusing on the knowledge representation expressivity resulting from it. Our approach allows the development of multi-agent applications where agents are able to use arguments in their decision-making processes as well as for communication. The framework has been successfully used as part of the development of a healthcare multi-agent prototype application.
2016 5th Brazilian Conference on Intelligent Systems (BRACIS), 2016
Argumentation-based reasoning plays an important role in agent reasoning and communication, yet l... more Argumentation-based reasoning plays an important role in agent reasoning and communication, yet little research has been carried out on the issues in integrating argumentation techniques into practical multi-agent platforms and the various sources of information in such systems. In this work, we extend an argumentation-based reasoning mechanism to take into account preferences over arguments supporting contrary conclusions, which in practice means the agent will be able to act more informedly, being able to decide on beliefs about which it would be otherwise ambivalent. Such preferences come from elements that are present or can be more easily obtained in the context of practical multi-agent programming platforms, such as multiple sources from which the information (used to construct the arguments) was acquired, as well as varying degrees of trust on them. Further, we introduce different agent profiles by varying the way certain operators are applied over the various information sources leading to the preferences over competing arguments in our approach. Unlike previous approaches, our approach accounts for multiple sources for a single piece of information and is based on an argumentation-based reasoning mechanism implemented on a multi-agent platform so arguably more computationally grounded than those approaches.
Electronic Notes in Theoretical Computer Science, 2016
In multi-agent systems, changes in an agent's mental state often reflect changes at the social le... more In multi-agent systems, changes in an agent's mental state often reflect changes at the social level as well. Furthermore, most work on agent languages use structural operational semantics to formalise multi-agent systems. As multi-agent systems are complex systems, it is difficult to formalise all relevant aspects of such system as a single transition system, and even transition systems for a single agent can easily become cumbersome. In this paper, we propose a particular style of semantic rules that make it visually clearer how changes at one level of a multi-agent system require simultaneous changes in other levels of the system (where each component of each level is modelled as a separate transition system).
2015 Brazilian Conference on Intelligent Systems (BRACIS), 2015
Argumentation is a key technique for reaching agreements in multi-agent systems. However, there a... more Argumentation is a key technique for reaching agreements in multi-agent systems. However, there are few practical approaches to develop multi-agent systems where agents engage in argumentation-based dialogues. In this paper, we give formal semantics to speech acts for argumentation-based dialogues in the context of an agent-oriented programming language. Our approach uses operational semantics and builds upon existing work that provides computationally grounded semantics for agent mental attitudes such as beliefs and goals. The paper also shows how our formal semantics can be used to prove properties of argumentation in multi-agent systems with direct reference to mental attitudes. We do so with an example of a proof sketch of termination of multi-agent dialogues under certain assumptions.
2015 IEEE/WIC/ACM International Conference on Web Intelligence and Intelligent Agent Technology (WI-IAT), 2015
Several advantages can be obtained by allowing multi-agent systems to easily access ontologies, f... more Several advantages can be obtained by allowing multi-agent systems to easily access ontologies, for example, in scenarios where agents make their decisions based on the knowledge provided by ontologies. Thus, this paper presents an infrastructure to allow the use of web ontologies in different agent-oriented platforms. The agents use this infrastructure layer as a tool for storing, accessing and querying domain-specific OWL ontologies. As a result, this layer allows an integration of agent platforms with semantic web data and ontologies. We exemplify in practice how agents, coded in one such platform, can use the proposed access layer to ontological reasoning engines, as well as which features can be obtained from it. The performance of this semantic infrastructure is evaluated and compared against usual knowledge representation in agent programming.
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inproceedings by Alison R Panisson