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Papers by M Gabriel Santos

Neuro-symbolic approaches to artificial intelligence, which combine neural networks with classica... more Neuro-symbolic approaches to artificial intelligence, which combine neural networks with classical symbolic techniques, are growing in prominence, necessitating formal approaches to reason about their correctness. We propose a novel modelling formalism called neuro-symbolic concurrent stochastic games (NS-CSGs), which comprise a set of probabilistic finite-state agents interacting in a shared continuous-state environment, observed through perception mechanisms implemented as neural networks. Since the environment state space is continuous, we focus on the class of NS-CSGs with Borel state spaces and Borel measurability restrictions on the components of the model. We consider the problem of zero-sum discounted cumulative reward, proving that NS-CSGs are determined and therefore have a value which corresponds to a unique fixed point. From an algorithmic perspective, existing methods to compute values and optimal strategies for CSGs focus on finite state spaces. We present, for the fir...

ArXiv, 2022

Game-theoretic techniques and equilibria analysis facilitate the design and verification of compe... more Game-theoretic techniques and equilibria analysis facilitate the design and verification of competitive systems. While algorithmic complexity of equilibria computation has been extensively studied, practical implementation and application of game-theoretic methods is more recent. Tools such as PRISM-games support automated verification and synthesis of zero-sum and (ε-optimal subgame-perfect) social welfare Nash equilibria properties for concurrent stochastic games. However, these methods become inefficient as the number of agents grows and may also generate equilibria that yield significant variations in the outcomes for individual agents. We extend the functionality of PRISM-games to support correlated equilibria, in which players can coordinate through public signals, and introduce a novel optimality criterion of social fairness, which can be applied to both Nash and correlated equilibria. We show that correlated equilibria are easier to compute, are more equitable, and can also ...

Brazilian Journal of Development, 2020

A Meliponicultura atua na conscientização ambiental e incrementa a renda de comunidades carentes ... more A Meliponicultura atua na conscientização ambiental e incrementa a renda de comunidades carentes no Maranhão Meliponicultura works to raise environmental awareness and increase the income of poor communities in Maranhão

2011 Brazilian Symposium on Computing System Engineering, 2011

Assuring the correctness of a system's behavior is a must when dealing with critical systems... more Assuring the correctness of a system's behavior is a must when dealing with critical systems. For instance, the Topcased project proposed several tools and methods in order to model such systems and to verify its behavior prior to implementation. In this scenario, the AADL modeling language plays a key role. Using this language, one can perform transformations to models with lower abstraction levels and perform the verification of properties. To ease this process, this paper presents a recently developed tool that provides a more intuitive way of constructing the sentences for property verification. It also helps the visualization of the verification results and enables to track the system's behavior from its initialization up to the point where the property couldn't be sustained. We illustrate its use and highlight its contributions with the modeling and verification of a pacemaker system.

Ciência Rural, 2011

A eliminação da etapa de enraizamento in vitro na micropropagação de plantas é desejável do ponto... more A eliminação da etapa de enraizamento in vitro na micropropagação de plantas é desejável do ponto de vista econômico, além de proporcionar a melhoria na qualidade do sistema radicial formado. Dois experimentos foram realizados com os objetivos de avaliar diferentes concentrações (0; 2,5; 5,0 e 10mM) de ácido indolbutírico (AIB) no enraizamento ex vitro de lavanda (L. angustifolia), cv. 'Provence Blue' e avaliar a capacidade de enraizamento ex vitro das cultivares 'Vera', 'Provence Blue',…

Talanta, 1968

The application of instrumental neutron-activation analysis to the study of metallogenic province... more The application of instrumental neutron-activation analysis to the study of metallogenic provinces is outlined. Iron, scandium and lanthanum are measured in uncrushed, whole-rock specimens, and the results indicate trace element compositional trends over the 50-mile traverse studied. These trends extend through a number of different formations and rock types, and reflect structural features mapped by others using conventional techniques.

International Journal of Sustainable Engineering, 2012

ABSTRACT Phosphorus-containing moieties can be added to the ninth and/or tenth positions of a fat... more ABSTRACT Phosphorus-containing moieties can be added to the ninth and/or tenth positions of a fatty chain of a methyl ester utilising an epoxide route. In this route, methyl oleate is epoxidised, and then ring opened using dibutyl phosphate to yield – among others – a dioxaphospholane-containing derivative of methyl octadecanoate. Progress of the reaction was determined by gas chromatography-mass spectrometry and compounds were identified by nuclear magnetic resonance spectroscopy. Addition of a titanium and zirconium oxide catalyst increased the yield of dioxaphospholane from 27%, observed without catalyst, to 37%. A similar reaction using bis-2-ethylhexyl phosphate gave 22% and 29% yield. However, an aryl phosphate, diphenyl phosphate, was not active in these reactions. The aliphatic compounds obtained are likely to be useful sulphur and metal-free extreme pressure lubricant additives which are highly compatible with vegetable oil-based lubricants.

Anais do Seminário de …, 2012