Learning policies through argumentation-derived evidence (extended abstract)

(c) IFAAMASPublisher PD

Rational decision making in autonomous agents

Making rational decisions is one of the key elements in the design of autonomous agents with successful behavior. Even though there have been many proposals for the support of decision making, most of them can be described either as descriptive or prescriptive. The main goal of our work is to establish the relationship between two of these models, namely bdi and mdps, in order to gain further understanding of how decisions in one model are viewed from the point of view of the other. This goal is important for the development of agent design strategies that unite the best of both worlds.Eje: Inteligencia artificial distribuida, aspectos teóricos de la inteligencia artificial y teoría de computaciónRed de Universidades con Carreras en Informática (RedUNCI

On the problem of comparing two models for rational decision making in autonomous agents

The main objective of this work is to establish a basis for comparing BDI agents with the optimality of decision theory models such as POMDPs. It is argued that a direct comparison is not possible due to the intractability of the algorithms used for solving POMDPs, and therefore an approximation must be used. We propose the reduction of the state space, and the combination of sub-solutions as the main approaches towards this goal. Throughout this work, the tileworld testbed is used as a frame of reference for the discussion of the various concepts.Eje: Agentes y Sistemas Inteligentes (ASI)Red de Universidades con Carreras en Informática (RedUNCI

In Situ Calls Of The Marine Perciform Glaucosoma Hebraicum

West Australian dhufish (Glaucosoma hebraicum), a marine perciform, possess a swim bladder which has associated muscles that are used in sound production. Individuals have been recorded producing sounds during capture that may be associated with disturbance from their normal behaviour. To determine whether individuals produce sound during natural behaviour, a passive sea-noise logger was deployed on the seafloor for one month in close proximity to low-relief artificialsubstrates occupied by G. hebraicum. During this time, both juvenile and sub-adult G. hebraicum were observed within metres of the logger on numerous occasions. At approximately the same time, sounds with characteristics similar to the disturbance calls of G. hebraicum were detected by the logger. Two types of swimbladder generated calls were recorded, one of widely-spaced pulses and the other of pulses in quick succession The maximum received levels and sound exposurelevels of the recorded calls were 132 dB re 1 μPa and 121 dB re 1 μPa2.s, respectively. Based on previously determined G. hebraicum source levels and time of arrival techniques (direct and surface-reflected ray paths), the vocalising fish were estimated at between 1 and 19.5 m from the hydrophone and thus within the area where they had been observed. This study has provided evidence that juvenile G. hebraicum produce sounds at similar source levels to those generated during human induced disturbance. This indicates that sound is produced by individuals of this species during normal behaviour, but may or may not be associated with natural sources of disturbance

Salicylaldehyde hydrazones: buttressing of outer sphere hydrogen-bonding and copper-extraction properties

Salicylaldehyde hydrazones are weaker copper extractants than their oxime derivatives, which are used in hydrometallurgical processes to recover ~20 % of the world’s copper. Their strength, based on the extraction equilibrium constant Ke, can be increased by nearly three orders of magnitude by incorporating electron-withdrawing or hydrogen-bond acceptor groups (X) ortho to the phenolic OH group of the salicylaldehyde unit. Density functional theory calculations suggest that the effects of the 3-X substituents arise from a combination of their influence on the acidity of the phenol in the pH-dependent equilibrium, Cu2+ + 2Lorg ⇌ [Cu(L–H)2]org + 2H+, and on their ability to ‘buttress’ interligand hydrogen bonding by interacting with the hydrazone N–H donor group. X-ray crystal structure determination and computed structures indicate that in both the solid state and the gas phase, coordinated hydrazone groups are less planar than coordinated oximes and this has an adverse effect on intramolecular hydrogen-bond formation to the neighbouring phenolate oxygen atoms

On the problem of comparing two models for rational decision making in autonomous agents

The main objective of this work is to establish a basis for comparing BDI agents with the optimality of decision theory models such as POMDPs. It is argued that a direct comparison is not possible due to the intractability of the algorithms used for solving POMDPs, and therefore an approximation must be used. We propose the reduction of the state space, and the combination of sub-solutions as the main approaches towards this goal. Throughout this work, the tileworld testbed is used as a frame of reference for the discussion of the various concepts.Eje: Agentes y Sistemas Inteligentes (ASI)Red de Universidades con Carreras en Informática (RedUNCI

Rational decision making in autonomous agents

Making rational decisions is one of the key elements in the design of autonomous agents with successful behavior. Even though there have been many proposals for the support of decision making, most of them can be described either as descriptive or prescriptive. The main goal of our work is to establish the relationship between two of these models, namely bdi and mdps, in order to gain further understanding of how decisions in one model are viewed from the point of view of the other. This goal is important for the development of agent design strategies that unite the best of both worlds.Eje: Inteligencia artificial distribuida, aspectos teóricos de la inteligencia artificial y teoría de computaciónRed de Universidades con Carreras en Informática (RedUNCI

Analysing Friedel averages and differences

Various practical applications of the average (A) and difference (D) of Friedel opposites are described. Techniques based on the resonant-scattering contribution to Friedel differences are applied to see whether a crystal is centrosymmetric or not, and to determine the point group of the crystal. For the validation of a structural study, plots of Aobs against Amodel, and Dobs against Dmodel are used extensively. Moreover, it is useful to display both plots on the same graph. Intensity measurements on a crystal of NaClO3 were made at three different speeds, with two different radiations and two different diffractometers, and treated with two different software packages and four different absorption corrections. The evaluation of these numerous data sets reveals underlying deficiencies. For comparison, plots of Aobs against Amodel, and Dobs against Dmodel are presented for two centrosymmetric crystals

High-pressure polymorphism in L-threonine between ambient pressure and 22 GPa

The crystal structure of l-threonine has been studied to a maximum pressure of 22.3 GPa using single-crystal X-ray and neutron powder diffraction. The data have been interpreted in the light of previous Raman spectroscopic data by Holanda et al. (J. Mol. Struct. (2015), 1092, 160-165) in which it is suggested that three phase transitions occur at ca. 2 GPa, between 8.2 and 9.2 GPa and between 14.0 and 15.5 GPa. In the first two of these transitions the crystal retains its P212121 symmetry, in the third, although the unit cell dimensions are similar either side of the transition, the space group symmetry drops to P21. The ambient pressure form is labelled phase I, with the successive high-pressure forms designated I′, II and III, respectively. Phases I and I′ are very similar, the transition being manifested by a slight rotation of the carboxylate group. Phase II, which was found to form between 8.5 and 9.2 GPa, follows the gradual transformation of a long-range electrostatic contact becoming a hydrogen bond between 2.0 and 8.5 GPa, so that the transformation reflects a change in the way the structure accommodates compression rather than a gross change of structure. Phase III, which was found to form above 18.2 GPa in this work, is characterised by the bifurcation of a hydroxyl group in half of the molecules in the unit cell. Density functional theory (DFT) geometry optimisations were used to validate high-pressure structural models and PIXEL crystal lattice and intermolecular interaction energies are used to explain phase stabilities in terms of the intermolecular interactions

Compression of glycolide-h4 to 6 GPa

This study details the structural characterisation of glycolide-h4 as a function of pressure to 6 GPa using neutron powder diffraction on the PEARL instrument at ISIS Neutron and Muon source. Glycolide-h4, rather than its deuterated isotopologue, was used in this study due to the difficulty of deuteration. The low-background afforded by Zirconia-Toughened Alumina (ZTA) anvils nevertheless enabled the collection of data suitable for structural analysis to be obtained to a pressure of 5 GPa. Glycolide-h4 undergoes a reconstructive phase transition at 0.15 GPa to a previously identified, form-II, which is stable to 6 GPa