Quantifying structure in networks

We investigate exponential families of random graph distributions as a framework for systematic quantification of structure in networks. In this paper we restrict ourselves to undirected unlabeled graphs. For these graphs, the counts of subgraphs with no more than k links are a sufficient statistics for the exponential families of graphs with interactions between at most k links. In this framework we investigate the dependencies between several observables commonly used to quantify structure in networks, such as the degree distribution, cluster and assortativity coefficients.Comment: 17 pages, 3 figure

Derivative pricing under the possibility of long memory in the supOU stochastic volatility model

We consider the supOU stochastic volatility model which is able to exhibit long-range dependence. For this model we give conditions for the discounted stock price to be a martingale, calculate the characteristic function, give a strip where it is analytic and discuss the use of Fourier pricing techniques. Finally, we present a concrete specification with polynomially decaying autocorrelations and calibrate it to observed market prices of plain vanilla options

Étude expérimentale de la formulation de mortier a base de sable silteux du Togo et de liant de sachets plastiques type « voltic »

La présente étude est destinée à valoriser les déchets plastiques par la recherche d’une formule optimale de mortier à base de sable silteux du Togo et de sachets plastiques fondus du type « voltic » offrant des propriétés mécaniques optimales. Trente six (36) échantillons de mortier à base de mélange de sable silteux et de liant de sachets plastiques à des dosages variant de 7% à 28% ont été préparés et soumis aux essais physiques et mécaniques après imbibition ou non dans de l’eau. Il ressort des résultats que le dosage en liant de sachets plastiques offrant de résistance optimale en compression (σc), au fendage (τd), en traction par flexion (σf) et par fendage (σd) varient de 16% à 22% avec des résistances à la rupture respectives d’environ 10,3 MPa (à 22%), 2,2 MPa (à 16%), 5,3 MPa (à 18%) et 1,4 MPa (à 16%). Le matériau présente des modules d’élasticité en compression (Ec), en flexion (Ef) et au fendage (Gd) respectivement d’environ 3 800 MPa, 700 MPa et 60 MPa pour des taux de liants de 22%. Pour de faibles taux de liants (8 à 10%), la densité du mortier et son absorption d’eau (en masse) sont optimales (respectivement de 1,95% et 0,29%). Cette absorption d’eau est nulle pour les teneurs en liant supérieures à 18% montrant le comportement étanche des mortiers. Les mortiers peuvent donc être utilisés pour les travaux de pavages, d’étanchement des toitures et de murs pour des taux de liants compris entre 18 à 22%.Mots-clés : mortier, sachets plastiques, sable silteux, eau, propriétés physico-mécaniques

A Hybrid Approach for Aspect-Based Sentiment Analysis Using Deep Contextual Word Embeddings and Hierarchical Attention

The Web has become the main platform where people express their opinions about entities of interest and their associated aspects. Aspect-Based Sentiment Analysis (ABSA) aims to automatically compute the sentiment towards these aspects from opinionated text. In this paper we extend the state-of-the-art Hybrid Approach for Aspect-Based Sentiment Analysis (HAABSA) method in two directions. First we replace the non-contextual word embeddings with deep contextual word embeddings in order to better cope with the word semantics in a given text. Second, we use hierarchical attention by adding an extra attention layer to the HAABSA high-level representations in order to increase the method flexibility in modeling the input data. Using two standard datasets (SemEval 2015 and SemEval 2016) we show that the proposed extensions improve the accuracy of the built model for ABSA.Comment: Accepted for publication in the 20th International Conference on Web Engineering (ICWE 2020), Helsinki Finland, 9-12 June 202

The application of the Raman Spectroscopy Method for Evaluating Implants from the Dura Mater

The results of a comparative spectral evaluation of the component composition of the surfaces of implants from the dura mater manufactured using the Lioplast technology with the use of ultrasound and sterilization are presented. Based on the analysis, coefficients were introduced reflecting the change in the relative concentration of components that determine the quality of the implants. It is established that Raman spectroscopy can be used to assess the change in the composition of implants based on the dura mater during their manufacture. Keywords: Raman spectroscopy, coefficients, spectral features, implants, dura mater

A Theory of Cheap Control in Embodied Systems

We present a framework for designing cheap control architectures for embodied agents. Our derivation is guided by the classical problem of universal approximation, whereby we explore the possibility of exploiting the agent's embodiment for a new and more efficient universal approximation of behaviors generated by sensorimotor control. This embodied universal approximation is compared with the classical non-embodied universal approximation. To exemplify our approach, we present a detailed quantitative case study for policy models defined in terms of conditional restricted Boltzmann machines. In contrast to non-embodied universal approximation, which requires an exponential number of parameters, in the embodied setting we are able to generate all possible behaviors with a drastically smaller model, thus obtaining cheap universal approximation. We test and corroborate the theory experimentally with a six-legged walking machine. The experiments show that the sufficient controller complexity predicted by our theory is tight, which means that the theory has direct practical implications. Keywords: cheap design, embodiment, sensorimotor loop, universal approximation, conditional restricted Boltzmann machineComment: 27 pages, 10 figure

Defect loops in gauged Wess-Zumino-Witten models

We consider loop observables in gauged Wess-Zumino-Witten models, and study the action of renormalization group flows on them. In the WZW model based on a compact Lie group G, we analyze at the classical level how the space of renormalizable defects is reduced upon the imposition of global and affine symmetries. We identify families of loop observables which are invariant with respect to an affine symmetry corresponding to a subgroup H of G, and show that they descend to gauge-invariant defects in the gauged model based on G/H. We study the flows acting on these families perturbatively, and quantize the fixed points of the flows exactly. From their action on boundary states, we present a derivation of the "generalized Affleck-Ludwig rule, which describes a large class of boundary renormalization group flows in rational conformal field theories.Comment: 43 pages, 2 figures. v2: a few typos corrected, version to be published in JHE

RoboCup 2D Soccer Simulation League: Evaluation Challenges

We summarise the results of RoboCup 2D Soccer Simulation League in 2016 (Leipzig), including the main competition and the evaluation round. The evaluation round held in Leipzig confirmed the strength of RoboCup-2015 champion (WrightEagle, i.e. WE2015) in the League, with only eventual finalists of 2016 competition capable of defeating WE2015. An extended, post-Leipzig, round-robin tournament which included the top 8 teams of 2016, as well as WE2015, with over 1000 games played for each pair, placed WE2015 third behind the champion team (Gliders2016) and the runner-up (HELIOS2016). This establishes WE2015 as a stable benchmark for the 2D Simulation League. We then contrast two ranking methods and suggest two options for future evaluation challenges. The first one, "The Champions Simulation League", is proposed to include 6 previous champions, directly competing against each other in a round-robin tournament, with the view to systematically trace the advancements in the League. The second proposal, "The Global Challenge", is aimed to increase the realism of the environmental conditions during the simulated games, by simulating specific features of different participating countries.Comment: 12 pages, RoboCup-2017, Nagoya, Japan, July 201

A Rydberg Quantum Simulator

Following Feynman and as elaborated on by Lloyd, a universal quantum simulator (QS) is a controlled quantum device which reproduces the dynamics of any other many particle quantum system with short range interactions. This dynamics can refer to both coherent Hamiltonian and dissipative open system evolution. We investigate how laser excited Rydberg atoms in large spacing optical or magnetic lattices can provide an efficient implementation of a universal QS for spin models involving (high order) n-body interactions. This includes the simulation of Hamiltonians of exotic spin models involving n-particle constraints such as the Kitaev toric code, color code, and lattice gauge theories with spin liquid phases. In addition, it provides the ingredients for dissipative preparation of entangled states based on engineering n-particle reservoir couplings. The key basic building blocks of our architecture are efficient and high-fidelity n-qubit entangling gates via auxiliary Rydberg atoms, including a possible dissipative time step via optical pumping. This allows to mimic the time evolution of the system by a sequence of fast, parallel and high-fidelity n-particle coherent and dissipative Rydberg gates.Comment: 8 pages, 4 figure