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- Paradigmatic analysis using genetic programmingPublication . Grilo, Carlos Fernando Almeida; Machado, Fernando; Cardoso, Fernando Amílcar BandeiraParadigmatic analysis consists in the segmentation of a musical piece through the identification of relations between different parts of the piece, and the classification of the identified segments into categories. In this paper we describe how a genetic programming system can be used to make the paradigmatic analysis of monophonic musical pieces, using a simple fitness function inspired in the Kolmogorov complexity estimation. We make use of automatically defined functions in order to represent segments. Relations are made explicit through the reuse of segments and the application of transformations to these segments.
- The influence of asynchronous dynamics in the spatial prisioner's dilemma gamePublication . Grilo, Carlos Fernando Almeida; Correia, LuísWe examine the influence of asynchronism in the Spatial Prisoner’s Dilemma game. Previous studies reported that less cooperation is achieved with the asynchronous version of the game than with the synchronous one. Here, we show that, in general, the opposite is the most common outcome. This conclusion is only possible because a larger number of scenarios was tested, namely, different interaction topologies, a transition rule that can be tuned to emulate different levels of determinism in the choice of the next strategy to be adopted and different rates of asynchronism. The influence of stochastic and deterministic periodic updating in the outcome of the system is also compared. We found that these two update disciplines lead basically to the same result. This is an important issue in the simulation of social and biological behavior.
- Towards a computational case-based model for creative planningPublication . Macedo, Luís; Pereira, Francisco C.; Grilo, Carlos Fernando Almeida; Cardoso, Fernando Amílcar BandeiraThis paper describes a computational case-based model for the creative planning process. Our approach is inspired in Wallas’ model for the creative process in that we consider that creativity involves a sequence of four stages: preparation, incubation, illumination and verification. Preparation includes problem acquisition and assimilation of background knowledge, which is represented by cases, i.e., documented past experiences. With the aim of achieving a flexible knowledge representation, as a means to potentiate specific creative abilities like Fluency, Synthesis and Analysis, we structure each case as a network of hierarchically and temporally related case pieces. These case pieces can be considered individually, providing better recombinations of them. These recombinations, rather than made by chance, are guided by those hierarchical and temporal case piece relations (or explanations). We explain the role of opportunistic knowledge acquisition at the incubation stage. We sustain that illumination may comprise recursive calls of the sequence of the first three stages. This computational model is implemented in the system INSPIRER (ImagiNation1 taking as Source Past and Imperfectly RElated Reasonings). An application in musical composition domain is presented. We also show how a musical composition task may be cognitively modelled and treated as a planning task. We also present a short example illustrating how INSPIRER generates music.
- What makes spatial prisioner's dilemma game sensitive to asynchronism?Publication . Grilo, Carlos Fernando Almeida; Correia, LuísWe investigate aspects that control the Spatial Prisoner’s Dilemma game sensitivity to the synchrony rate of the model. Based on simulations done with the generalized proportional and the replicator dynamics transition rules, we conclude that the sensitivity of the game to the synchrony rate depends almost exclusively on the transition rule used to model the strategy update by the agents. We then identify the features of these transition rules that are responsible for the sensitivity of the game. The results show that the Spatial Prisoner’s Dilemma game becomes more and more sensitive for noise levels above a given noise threshold. Below this threshold, the game is robust to the noise level and its robustness even slightly grows, compared to the imitate the best strategy, if a small amount of noise is present in the strategy update process.
- An automatic generation of textual pattern rules for digital content filters proposal, using grammatical evolution genetic programmingPublication . Basto-Fernandes, Vitor; Yevseyeva, Iryna; Frantz, Rafael Z.; Grilo, Carlos Fernando Almeida; Díaz, Noemí Pérez; Emmerich, Michael
- Plans as structured networks of hierarchically and temporally related case piecesPublication . Macedo, Luís; Pereira, Francisco C.; Grilo, Carlos Fernando Almeida; Cardoso, Fernando Amílcar BandeiraThis paper describes a representation of plan cases as a structured set of goals and actions. These goals and actions are the unit pieces that form a case. These case pieces are related each other by hierarchical and temporal links (explanations) forming a tree-like network. We give importance not just to explicit links, i.e., links between case pieces which are concretely known, but also to implicit ones, i.e., possibly unknown links between case pieces. Each case piece is explained by antecedent links and explains other case pieces by consequent links. The retrieval of a case piece is mainly guided by its links and by its surrounding case pieces. Our concept of case piece usefulness is briefly explained. We discuss the benefit of reusing and directly accessing small case pieces from multiple cases for improving the Case-Based Reasoning (CBR) systems’ capability and efficiency to solve problems. We explain the importance of stepwise refinement in plan cases and also the role that temporal representation can take in the meaningful and coherent construction of planning problem solutions. An application in musical composition domain is presented. We also show how a musical composition task can be treated as a planning task.
- Musical pattern extraction using genetic algorithmsPublication . Grilo, Carlos Fernando Almeida; Cardoso, Fernando Amílcar BandeiraThis paper describes a research work in which we study the possibility of applying genetic algorithms to the extraction of musical patterns in monophonic musical pieces. Each individual in the population represents a possible segmentation of the piece being analysed. The goal is to find a segmentation that allows the identification of the most significant patterns of the piece. In order to calculate an individual’s fitness, all its segments are compared among each other. The bigger the area occupied by similar segments the better the quality of the segmentation.
- Effects of asynchronism on evolutionary gamesPublication . Grilo, Carlos Fernando Almeida; Correia, LuísWe analyze the influence of the update dynamics on symmetric 2-player evolutionary games, which are among the most used tools to study the emergence of cooperation in populations of interacting agents. A synchronous dynamics means that, at each time step, all the agents of the population update their strategies simultaneously. An extreme case of asynchronism is sequential dynamics, in which only one agent is updated each time. We first show that these two opposite update dynamics can lead to very different outcomes and that sequential dynamics is detrimental to the emergence of cooperation only when the probability of imitating the most successful neighbors is high. In this sense, we can say that, when the update dynamics has some influence, in general asynchronism is beneficial to the emergence of cooperation.Wethen explore the consequences of using intermediate levels of asynchronism, where only a fraction of the agents update their behavior each time. In general, the level of cooperation changes smoothly and monotonically as we gradually go from synchronous to sequential dynamics. However, there are some exceptions that should be taken into account. In addition, the results show that the possibility of agents taking irrational decisions has a key role in the sensitivity of thesemodels to changes in the update dynamics. Explanations for the observed behaviors are advanced.
- A structured framework for representing time in a generative composition systemPublication . Pereira, Francisco C.; Grilo, Carlos Fernando Almeida; Macedo, Luís; Cardoso, Fernando Amílcar BandeiraThe representation of music structures is, from Musicology to Artificial Intelligence, a widely known research focus. It entails several generic Knowledge Representation problems like structured knowledge representation, time representation and causality. In this paper, we focus the problem of representing and reasoning about time in the framework of a structured music representation approach, intended to support the development of a Case-Based generative composition system. The basic idea of this system is to use Music Analysis as foundation for a generative process of composition, providing a structured and constrained way of composing novel pieces, although keeping the essential traits of the composer’s style. We propose a solution that combines a tree-like representation with a pseudo-dating scheme to provide an efficient and expressive means to deal with the problem.
- Selection of cooperative partners in n-player gamesPublication . Mariano, Pedro; Correia, Luís; Grilo, Carlos Fernando AlmeidaWe address the problem of finding the appropriate agents to interact with in n-player games. In our model an agent only requires knowledge about the payoff and identification of its partners. This information is used to update a probability distribution over candidate partners. As such, our model is applicable in any situation, be it a cooperative dilemma or a game where a Nash Equilibrium is equal to a Pareto Optimal profile.
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