10,183 research outputs found
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
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Attitudes of students towards peers with special educational needs in mainstream Portuguese schools
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
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
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
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