1,990 research outputs found
Evolutionary games on graphs
Game theory is one of the key paradigms behind many scientific disciplines
from biology to behavioral sciences to economics. In its evolutionary form and
especially when the interacting agents are linked in a specific social network
the underlying solution concepts and methods are very similar to those applied
in non-equilibrium statistical physics. This review gives a tutorial-type
overview of the field for physicists. The first three sections introduce the
necessary background in classical and evolutionary game theory from the basic
definitions to the most important results. The fourth section surveys the
topological complications implied by non-mean-field-type social network
structures in general. The last three sections discuss in detail the dynamic
behavior of three prominent classes of models: the Prisoner's Dilemma, the
Rock-Scissors-Paper game, and Competing Associations. The major theme of the
review is in what sense and how the graph structure of interactions can modify
and enrich the picture of long term behavioral patterns emerging in
evolutionary games.Comment: Review, final version, 133 pages, 65 figure
Building a poker playing agent based on game logs using supervised learning
Tese de mestrado integrado. Engenharia Informática e Computação. Faculdade de Engenharia. Universidade do Porto. 201
Evaluating reinforcement learning for game theory application learning to price airline seats under competition
Applied Game Theory has been criticised for not being able to model real decision making situations. A game's sensitive nature and the difficultly in determining the utility payoff functions make it hard for a decision maker to rely upon any game theoretic results. Therefore the models tend to be simple due to the complexity of solving them (i.e. finding the equilibrium).In recent years, due to the increases of computing power, different computer modelling techniques have been applied in Game Theory. A major example is Artificial Intelligence methods e.g. Genetic Algorithms, Neural Networks and Reinforcement Learning (RL). These techniques allow the modeller to incorporate Game Theory within their models (or simulation) without necessarily knowing the optimal solution. After a warm up period of repeated episodes is run, the model learns to
play the game well (though not necessarily optimally). This is a form of simulation-optimization.The objective of the research is to investigate the practical usage of RL within a simple sequential stochastic airline seat pricing game. Different forms of RL are considered and compared to the optimal policy, which is found using standard dynamic programming techniques. The airline game and RL methods displays various interesting phenomena, which are also discussed. For completeness, convergence proofs for
the RL algorithms were constructed
Quantum computing for finance
Quantum computers are expected to surpass the computational capabilities of
classical computers and have a transformative impact on numerous industry
sectors. We present a comprehensive summary of the state of the art of quantum
computing for financial applications, with particular emphasis on stochastic
modeling, optimization, and machine learning. This Review is aimed at
physicists, so it outlines the classical techniques used by the financial
industry and discusses the potential advantages and limitations of quantum
techniques. Finally, we look at the challenges that physicists could help
tackle
Quantum random number generators for industrial applications
Premi extraordinari doctorat UPC curs 2017-2018.
Àmbit de CiènciesRandomness is one of the most intriguing, inspiring and debated topics in the history of the world. It appears every time we wonder about our existence, about the way we are, e.g. Do we have free will? Is evolution a result of chance? It is also present in any attempt to understand our anchoring to the universe, and about the rules behind the universe itself, e.g. Why are we here and when and why did all this start? Is the universe deterministic or does unpredictability exist? Remarkably, randomness also plays a central role in the information era and technology. Random digits are used in communication protocols like Ethernet, in search engines and in processing algorithms as page rank. Randomness is also widely used in so-called Monte Carlo methods in physics, biology, chemistry, finance and mathematics, as well as in many other disciplines. However, the most iconic use of random digits is found in cryptography. Random numbers are used to generate cryptographic keys, which are the most basic element to provide security and privacy to any form of secure communication.
This thesis has been carried out with the following questions in mind: Does randomness exist in photonics? If so, how do we mine it and how do we mine it in a massively scalable manner so that everyone can easily use it? Addressing these two questions lead us to combine tools from fundamental physics and engineering. The thesis starts with an in-depth study of the phase diffusion process in semiconductor lasers and its application to random number generation. In contrast to other physical processes based on deterministic laws of nature, the phase diffusion process has a pure quantum mechanical origin, and, as such, is an ideal source for generating truly unpredictable digits.
First, we experimentally demonstrated the fastest quantum random number generation scheme ever reported (at the time), using components from the telecommunications industry only. Up to 40 Gb/s were demonstrated to be possible using a pulsed scheme. We then moved towards building prototypes and testing them with partners in supercomputation and fundamental research. In particular, the devices developed during this thesis were used in the landmark loophole- free Bell test experiments of 2015. In the process of building the technology, we started a new research focus as an attempt to answer the following question: How do we know that the digits that we generate are really coming from the phase diffusion process that we trust? As a result, we introduced the randomness metrology methodology, which can be used to derive quantitative bounds on the quality of any physical random number generation device. Finally, we moved towards miniaturisation of the technology by leveraging techniques from the photonic integrated circuits technology industry. The first fully integrated quantum random number generator was demonstrated using a novel two-laser scheme on an Indium Phosphide platform. In addition, we also demonstrated the integration of part of the technology on a Silicon Photonics platform, opening the door towards manufacturing in the most advanced semiconductor industry.L’aleatorietat és un dels temes més intrigants, inspiradors i debatuts al llarg de la història. És un concepte que sorgeix quan ens preguntem sobre la nostra pròpia existència i de per què som com som. Tenim freewill? És l’evolució resultat de l’atzar? L’aleatorietat és també un tema que
sorgeix quan intentem entendre la nostra relació amb l’univers mateix. Per què estem aqu� Quan o com va començar tot això? És l’univers una mà quina determinista o hi ha cabuda per a l’atzar? Sorprenentment, l’aleatorietat també juga un paper crucial en l’era de la informació i la tecnologia.
Els nombres aleatoris es fan servir en protocols de comunicació com Ethernet, en algoritmes de classificació i processat com Page Rank. També usem l’aleatorietat en els mètodes Monte Carlo, que s’utilitzen en els à mbits de la fÃsica, la biologia, la quÃmica, les finances o les matemà tiques. Malgrat això, l’aplicació més icònica per als nombres aleatoris la trobem en el camp de la criptografia o ciber-seguretat. Els nombres aleatoris es fan servir per a generar claus criptogrà fiques, l’element bà sic que proporciona la seguretat i privacitat a les nostres comunicacions.
Aquesta tesi parteix de la següent pregunta fonamental: Existeix l’aleatorietat a la fotònica? En cas afirmatiu, com podem extreure-la i ferla accessible a tothom? Per a afrontar aquestes dues preguntes, s’han combinat eines des de la fÃsica fonamental fins a l’enginyeria. La tesi parteix d’un estudi detallat del procés de difusió de fase en là sers semiconductors i de com aplicar aquest procés per a la generació de nombres aleatoris. A diferència d’altres processos fÃsics basats en lleis deterministes de la natura, la difusió de fase té un origen purament quà ntic, i per
tant, és una font ideal per a generar nombres aleatoris.
Primerament, i fent servir aquest procés de difusió de fase, vam crear el generador quà ntic de nombres aleatoris més rà pid mai implementat (en aquell moment) fent servir, únicament, components de la indústria de les telecomunicacions. Més de 40 Gb/s van ser demostrats fent servir un esquema de là ser polsat. Posteriorment, vam construir diversos prototips que van ser testejats en aplicacions de ciència fonamental i supercomputació.
En particular, alguns dels prototips desenvolupats en aquesta tesi van ser claus en els famosos experiments loophole-free Bell tests realitzats l’any 2015. En el procés de construir aquests prototips, vam iniciar una nova lÃnia de recerca per a intentar contestar una nova pregunta:
Com sabem si els nombres aleatoris que generem realment sorgeixen del procés de difusió de fase, tal com nosaltres creiem? Com a resultat, vam introduir una nova metodologia, la metrologia de l’aleatorietat. Aquesta es pot fer servir per a derivar lÃmits quantificables sobre la qualitat de qualsevol dispositiu de generació de nombres aleatoris fÃsic. Finalment, ens vam moure en la direcció de la miniaturització de la tecnologia utilitzant tècniques de la indústria de la fotònica integrada. En particular, vam demostrar el primer generador de nombres aleatoris quà ntic totalment integrat, fent servir un esquema de dos là sers en un xip de Fosfur d’Indi.
En paral·lel, també vam demostrar la integració d’una part del dispositiu emprant tecnologia de Silici, obrint les portes, per tant, a la producció a gran escala a través de la indústria més avançada de semiconductors.La aleatoriedad es uno de los temas más intrigantes, inspiradores y debatidos a lo largo de la historia. Es un concepto que surge cuando nos preguntamos sobre nuestra propia existencia y de por qué somos como somos. ¿Tenemos libre albedrÃo? ¿Es la evolución resultado del azar? La aleatoriedad es también un tema que surge cuando intentamos entender nuestra relación con el universo. ¿Por qué estamos aquÃ? ¿Cuándo y cómo empezó todo esto? ¿Es el universo una máquina determinista o existe espacio para el azar? Sorprendentemente, la aleatoriedad también juega un papel crucial en la era de la información y la tecnologÃa. Los números aleatorios se usan en protocolos de comunicación como Ethernet, y en algoritmos de clasificación y procesado como Page Rank. También la utilizamos en los métodos Monte Carlo, que sirven en los ámbitos
de la fÃsica, la biologÃa, la quÃmica, las finanzas o las matemáticas. Sin embargo, la aplicación más icónica para los números aleatorios la encontramos en el campo de la criptografÃa y la ciberseguridad. AquÃ, los números aleatorios se usan para generar claves criptográficas, proporcionando el elemento básico para dotar a nuestras comunicaciones de seguridad y privacidad.
En esta tesis partimos de la siguiente pregunta fundamental: ¿Existe la aleatoriedad en la fotónica? En caso afirmativo, ¿Cómo podemos extraerla y hacerla accesible a todo el mundo? Para afrontar estas dos preguntas, se han combinado herramientas desde la fÃsica fundamental hasta la ingenierÃa. La tesis parte de un estudio detallado del proceso
de difusión de fase en láseres semiconductores y de cómo aplicar este proceso para la generación de números aleatorios. A diferencia de otros procesos fÃsicos basados en leyes deterministas de la naturaleza, la difusión de fase tiene un origen puramente cuántico y, por lo tanto, es una fuente ideal para generar números aleatorios.
Primeramente, y utilizando este proceso de difusión de fase, creamos el generador cuántico de números aleatorios más rápido nunca implementado (en ese momento) utilizando únicamente componentes de la industria de las telecomunicaciones. Más de 40 Gb/s fueron demostrados utilizando un esquema de láser pulsado. Posteriormente, construimos varios prototipos que fueron testeados en aplicaciones de ciencia fundamental y supercomputación. En particular, algunos de los prototipos desarrollados en esta tesis fueron claves en los famosos experimentos Loophole-free Bell tests realizados en el 2015. En el proceso de construir estos prototipos, iniciamos una nueva lÃnea de investigación para intentar dar respuesta a una nueva pregunta: ¿Cómo sabemos si
los números aleatorios que generamos realmente surgen del proceso de difusión de fase, tal y como nosotros creemos? Como resultado introdujimos una nueva metodologÃa, la metrologÃa de la aleatoriedad. Esta se puede usar para derivar lÃmites cuantificables sobre la calidad de cualquier dispositivo de generación de números aleatorios fÃsico. Finalmente, nos movimos en la dirección de la miniaturización de la tecnologÃa utilizando técnicas de la industria de la fotónica integrada. En particular, creamos el primer generador de números aleatorios cuántico totalmente integrado utilizando un esquema de dos láseres en un chip de Fosfuro de Indio.
En paralelo, también demostramos la integración de una parte del dispositivo utilizando tecnologÃa de Silicio, abriendo las puertas, por tanto, a la producción a gran escala a través de la industria más avanzada de semiconductores.Award-winningPostprint (published version
Learning-based Attacks in Cyber-Physical Systems
We introduce the problem of learning-based attacks in an abstraction of cyber-physical systems that may be subject to an attack that overrides the sensor readings and the controller actions. The attacker attempts to learn the dynamics of the plant and subsequently override the controller's actuation signal, to destroy the plant without being detected. The attacker can feed fictitious sensor readings to the controller using its estimate of the plant dynamics and mimic the legitimate plant operation. The controller, on the other hand, is constantly on the lookout for an attack; once the controller detects an attack, it immediately shuts the plant off. We derive lower bounds for the attacker's deception probability for linear plants by assuming a specific authentication test that inspects the empirical variance of the system disturbance. We also show how the controller can improve the security of the system by superimposing a carefully crafted privacy-enhancing signal on top of the control policy. Finally, for nonlinear scalar dynamics that belong to the Reproducing Kernel Hilbert Space, we investigate the performance of attacks based on Gaussian-processes regression
Hidden Citations Obscure True Impact in Science
References, the mechanism scientists rely on to signal previous knowledge,
lately have turned into widely used and misused measures of scientific impact.
Yet, when a discovery becomes common knowledge, citations suffer from
obliteration by incorporation. This leads to the concept of hidden citation,
representing a clear textual credit to a discovery without a reference to the
publication embodying it. Here, we rely on unsupervised interpretable machine
learning applied to the full text of each paper to systematically identify
hidden citations. We find that for influential discoveries hidden citations
outnumber citation counts, emerging regardless of publishing venue and
discipline. We show that the prevalence of hidden citations is not driven by
citation counts, but rather by the degree of the discourse on the topic within
the text of the manuscripts, indicating that the more discussed is a discovery,
the less visible it is to standard bibliometric analysis. Hidden citations
indicate that bibliometric measures offer a limited perspective on quantifying
the true impact of a discovery, raising the need to extract knowledge from the
full text of the scientific corpus
Artificial and Computational Intelligence in Games (Dagstuhl Seminar 12191)
This report documents the program and the outcomes of Dagstuhl Seminar 12191 "Artificial and Computational Intelligence in Games". The aim for the seminar was to bring together creative experts in an intensive meeting with the common goals of gaining a deeper understanding of various aspects of artificial and computational intelligence in games, to help identify the main challenges in game AI research and the most promising venues to deal with them. This was accomplished mainly by means of workgroups on 14 different topics (ranging from search, learning, and modeling to architectures, narratives, and evaluation), and plenary discussions on the results of the workgroups. This report presents the conclusions that each of the workgroups reached. We also added short descriptions of the few talks that were unrelated to any of the workgroups
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