Partial Classification of Lorenz Knots: Syllable Permutations of Torus Knots Words

We define families of aperiodic words associated to Lorenz knots that arise naturally as syllable permutations of symbolic words corresponding to torus knots. An algorithm to construct symbolic words of satellite Lorenz knots is defined. We prove, subject to the validity of a previous conjecture, that Lorenz knots coded by some of these families of words are hyperbolic, by showing that they are neither satellites nor torus knots and making use of Thurston's theorem. Infinite families of hyperbolic Lorenz knots are generated in this way, to our knowledge, for the first time. The techniques used can be generalized to study other families of Lorenz knots

Evolution of Swarm Robotics Systems with Novelty Search

Novelty search is a recent artificial evolution technique that challenges traditional evolutionary approaches. In novelty search, solutions are rewarded based on their novelty, rather than their quality with respect to a predefined objective. The lack of a predefined objective precludes premature convergence caused by a deceptive fitness function. In this paper, we apply novelty search combined with NEAT to the evolution of neural controllers for homogeneous swarms of robots. Our empirical study is conducted in simulation, and we use a common swarm robotics task - aggregation, and a more challenging task - sharing of an energy recharging station. Our results show that novelty search is unaffected by deception, is notably effective in bootstrapping the evolution, can find solutions with lower complexity than fitness-based evolution, and can find a broad diversity of solutions for the same task. Even in non-deceptive setups, novelty search achieves solution qualities similar to those obtained in traditional fitness-based evolution. Our study also encompasses variants of novelty search that work in concert with fitness-based evolution to combine the exploratory character of novelty search with the exploitatory character of objective-based evolution. We show that these variants can further improve the performance of novelty search. Overall, our study shows that novelty search is a promising alternative for the evolution of controllers for robotic swarms.Comment: To appear in Swarm Intelligence (2013), ANTS Special Issue. The final publication will be available at link.springer.co

Assigning Polarity Automatically to the Synsets of a Wordnet-like Resource

This article describes work towards the automatic creation of a conceptual polarity lexicon for Portuguese. For this purpose, we take advantage of a polarity lexicon based on single lemmas to assign polarities to the synsets of a wordnet-like resource. We assume that each synset has the polarity of the majority of its lemmas, given by the initial lexicon. After that, polarity is propagated to other synsets, through different types of semantic relations. The relation types used were selected after manual evaluation. The main result of this work is a lexicon with more than 10,000 synsets with an assigned polarity, with accuracy of 70% or 79%, depending on the human evaluator. For Portuguese, this is the first synset-based polarity lexicon we are aware of. In addition to this contribution, the presented approach can be applied to create similar resources for other languages

Individual decision making in task-oriented groups

The strategies adopted by individuals to select relevant information to pass on are central to understanding problem solving by groups. Here we use agent-based simulations to revisit a cooperative problem-solving scenario where the task is to find the common card in decks distributed to the group members. The agents can display only a sample of their cards and we explore different strategies to select those samples based on the confidences assigned to the cards. An agent's confidence that a particular card is the correct one is given by the number of times it observed that card in the decks of the other agents. We use a Gibbs distribution to select the card samples with the temperature measuring the strength of a noise that prevents the agents to correctly rank the cards. The group is guaranteed to find the common card in all runs solely in the infinite temperature limit, where the cards are sampled regardless of their confidences. In this case, we obtain the scaling form of the time constant that characterizes the asymptotic exponential decay of the failure probability. For finite time, however, a finite temperature yields a probability of failure that is several orders of magnitude lower than in the infinite temperature limit. The available experimental results are consistent with the decision-making model for finite temperature only

Policies for allocation of information in task-oriented groups: elitism and egalitarianism outperform welfarism

Communication or influence networks are probably the most controllable of all factors that are known to impact on the problem-solving capability of task-forces. In the case connections are costly, it is necessary to implement a policy to allocate them to the individuals. Here we use an agent-based model to study how distinct allocation policies affect the performance of a group of agents whose task is to find the global maxima of NK fitness landscapes. Agents cooperate by broadcasting messages informing on their fitness and use this information to imitate the fittest agent in their influence neighborhoods. The larger the influence neighborhood of an agent, the more links, and hence information, the agent receives. We find that the elitist policy in which agents with above-average fitness have their influence neighborhoods amplified, whereas agents with below-average fitness have theirs deflated, is optimal for smooth landscapes, provided the group size is not too small. For rugged landscapes, however, the elitist policy can perform very poorly for certain group sizes. In addition, we find that the egalitarian policy, in which the size of the influence neighborhood is the same for all agents, is optimal for both smooth and rugged landscapes in the case of small groups. The welfarist policy, in which the actions of the elitist policy are reversed, is always suboptimal, i.e., depending on the group size it is outperformed by either the elitist or the egalitarian policies

Sequenciação de Nova Geração: tecnologia de ponta no INSA para apoio à identificação e caracterização de surtos, situações de emergência e à decisão clínica [editorial]

Os avanços recentes nas tecnologias de sequenciação de ácidos nucleicos, associados à progressiva diminuição dos seus custos, têm permitido aos laboratórios de Microbiologia Clínica utilizar, de forma cada vez mais frequente, a técnica de Sequenciação Total do Genoma (vulgarmente referenciada na literatura por Whole Genome Sequencing - WGS). De facto, esta tecnologia tem emergido como uma ferramenta de ponta para complementar e/ou substituir as tradicionais metodologias da Microbiologia Clínica, influenciando o diagnóstico, a monitorização epidemiológica e as atividades de investigação/desenvolvimento de virtualmente todos os agentes patogénicos (desde vírus e bactérias a fungos e parasitas). O Instituto Nacional de Saúde Doutor Ricardo Jorge (INSA) adquiriu recentemente um equipamento de sequenciação de nova geração, o qual tem permitido inequivocamente um “virar de página” em termos de progresso tecnológico e de serviços oferecidos à comunidade médico-científica

El educador reflexivo : notas para la orientación de sus prácticas docentes

Este trabajo tiene como objetivo principal propiciar momentos de reflexión en la práctica pedagógica del profesor, sobre su «compromiso» con su profesión y con la educación. Consecuentemente, abre espacios para la discusión de la reflexión-en-la-acción como la práctica indispensable del día a día, enumera puntos que pueden constituir obstáculos para la práctica reflexiva y construye otros que proporcionarán las huellas para llevar a cabo un trabajo pedagógico eficiente y eficaz.Aquest treball té per objecte principal propiciar moments de reflexió en la pràctica pedagògica del professor, sobre el seu compromís amb la professió i amb l'educació. Consegüentment, obre espais per a la discussió de la reflexió en l'acció com la pràctica indispensable de l'activitat quotidiana, enumera punts que poden causar obstacles per a la pràctica reflexiva i en construeix uns altres que proporcionen les petjades per realitzar un treball pedagògic eficient i eficaç.The main objective of this work is to foster moments of reflection about the teacher's pedagogical practice and about his/her compromise with his/her profession and education. It allows the creation of spaces of discussion about the reflection-into-action as a necessary daily practice and it considers the obstacles of reflective practice as well as the benefits that help build an efficient pedagogical performance