Free access to paper accepted at GECCO’14

During 1 month, papers accepted at GECCO1’4 will be freely available. Thus, you can get and read our papers:

  • “Assessing different architectures for evolutionary algorithms in javascript” by Juan Julián Merelo, Pedro Castillo, Antonio Mora, Anna I. Esparcia-Alcázar, Víctor M. Rivas Santos (doi 10.1145/2598394.2598460) at http://goo.gl/jqLud5
  • NodEO, a multi-paradigm distributed evolutionary algorithm platform in JavaScript” by Juan-Julián Merelo, Pedro Castillo, Antonio Mora, Anna Esparcia-Alcázar, Víctor Rivas-Santos (doi:10.1145/2598394.2605688) at http://goo.gl/eFmv1T
  • “Enforcing corporate security policies via computational intelligence techniques” by Antonio M. Mora, Paloma De las Cuevas, Juan Julián Merelo, Sergio Zamarripa, Anna I. Esparcia-Alcázar (doi: 10.1145/2598394.2605438) at http://goo.gl/33gWES
  • A methodology for designing emergent literary backstories on non-player characters using genetic algorithms”, by Rubén Héctor García-Ortega, Pablo García-Sánchez, Antonio Miguel Mora, Juan Julián Merelo (doi: 10.1145/2598394.2598482) at http://goo.gl/9CEcMc

Enjoy!

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Evolution using JavaScript in EvoStar

JavaScript, despite its age, is considered now an emergent language, since it is starting to have a ecosystem that allows the development of complex and high-performance applications. That is why in the recent EvoStar we had a poster that uses evolutionary algorithms libraries written using it. It is based on MOOTools to create an object-oriented browser-based library called jsEO, and is entitled An object-oriented library in JavaScript to build modular and flexible cross-platform evolutionary algorithms.

Unreliable Heterogeneous Workers in a pool-based evolutionary algorithm

by Mario Garcia-Valdez, Juan-J. Merelo, Francisco Fernández de Vega
in  EvoAPPS posters

In this paper the effect of node unavailability in algorithms using EvoSpace, a pool-based evolutionary algorithm, is assessed. EvoSpace is a framework for developing evolutionary algorithms (EAs) using heterogeneous and unreliable resources. It is based on Linda’s tuple space coordination model. The core elements of EvoSpace are a central repository for the evolving population and remote clients, here called EvoWorkers, which pull random samples of the population to perform on them the basic evolutionary processes (selection, variation and survival), once the work is done, the modified sample is pushed back to the central population. To address the problem of unreliable EvoWorkers, EvoSpace uses a simple re-insertion algorithm using copies of samples stored in a global queue which also prevents the starvation of the population pool. Using a benchmark problem from the P-Peaks problem generator we have compared two approaches: (i) the re-insertion of previous individuals at the cost of keeping copies of each sample, and a common approach of other pool based EAs, (ii) inserting randomly generated  individuals. We found that EvoSpace is fault tolerant to highly unreliable resources and also that the re-insertion algorithm is only needed when the population is near the point of starvation.

An object-oriented library in JavaScript to build modular and flexible cross- platform evolutionary algorithms

by Victor Manuel Rivas Santos, Maria Isabel Garcia Arenas, Juan Julian Merelo Guervos, Antonio Mora Garcia and Gustavo Romero Lopez.
In EvoAPPS posters (see the poster at slideshare)

This paper introduces jsEO, a new evolutionary computation library that is executed in web browsers, as it is written in Javascript. The  library allows the rapid development of evolutionary algorithm, and makes easier the collaboration between different clients by means of individuals stored in a web server. In this work, jsEO has been tested against two simple problems, such as the Royal Road function and a 128-terms equation, and analysing how many machines and evaluations it yields. This paper attempts to reproduce results of older papers using modern browsers and all kind of devices that, nowadays, have JavaScript integrated in the browser, and is a complete rewrite of the code using the popular MooTools library. Results show that the system makes easier the development of evolutionary algorithms, suited for different chromosomes representations and problems, that can be simultaneously executed in many different operating systems and web browsers, sharing the best solutions previously found.

Evolving Evil: Optimizing Flocking Strategies through Genetic Algorithms for the Ghost Team in the Game of Ms. Pac-Man

by Federico Liberatore, Antonio Mora, Pedro Castillo, Juan Julián Merelo in EvoGAMES
Flocking strategies are sets of behavior rules for the interaction of agents that allow to devise controllers with reduced complexity that generate emerging behavior. In this paper, we present an application of genetic algorithms and flocking strategies to control the Ghost Team in the game Ms. Pac-Man. In particular, we define flocking strategies for the Ghost Team and optimize them for robustness with respect to the stochastic elements of the game and effectivity against different possible opponents by means of genetic algorithm. 
The performance of the methodology proposed is tested and compared with that of other standard controllers belonging to the framework of the Ms. Pac-Man versus Ghosts Competition. The results show that flocking strategies are capable of modelling complex behaviors and produce effective and challenging agents. 

The presentation is:

 

You can also see a brief demo here (we are the ghosts :D):

Enjoy it!

(And cite us, of course :D)

Volunteer-based evolutionary algorithms al dente

Planning the cook of a time consuming optimization problem? Have you considered to let a crowd of volunteers to help you in this endeavor? In a volunteer-based system,  volunteers provide you with free ingredients (CPU cycles, memory, internet connection,..) to be seasoned with only a pinch of peer-to-peer or desktop-grid technology.

If you are looking for a delicious cook of a volunteer-based evolutionary algorithm, you can find our recipe in this paper published in Genetic Programming and Evolvable Machines (pre-print version available here)

Title: “Designing robust volunteer-based evolutionary algorithms

Abstract This paper tackles the design of scalable and fault-tolerant evolutionary algorithms computed on volunteer platforms. These platforms aggregate computational resources from contributors all around the world. Given that resources may join the system only for a limited period of time, the challenge of a volunteer-based evolutionary algorithm is to take advantage of a large amount of computational power that in turn is volatile. The paper analyzes first the speed of convergence of massively parallel evolutionary algorithms. Then, it provides some guidance about how to design efficient policies to overcome the algorithmic loss of quality when the system undergoes high rates of transient failures, i.e. computers fail only for a limited period of time and then become available again. In order to provide empirical evidence, experiments were conducted for two well-known problems which require large population sizes to be solved, the first based on a genetic algorithm and the second on genetic programming. Results show that, in general, evolutionary algorithms undergo a graceful degradation under the stress of losing computing nodes. Additionally, new available nodes can also contribute to improving the search process. Despite losing up to 90% of the initial computing resources, volunteer-based evolutionary algorithms can find the same solutions in a failure-prone as in a failure-free run.

Sistemas Clasificadores

Los sistemas clasificadores son una fusión entre los algoritmos evolutivos, el aprendizaje por refuerzo y el supervisado. Se conocen como Learning Classifier Systems. El viernes pasado aproveché la reunión del grupo para presentar una breve revisión histórica y dar detalles sobre quizá el algoritmo más importante introducido en este campo, el eXtended Classifier System o XCS de Wilson.

Básicamente, el algoritmo busca mediante evolución genética y aprendizaje un conjunto de reglas que modelen la solución a un problema donde existe recompensa. Las reglas se componen de una condición y una acción. La población de reglas representa para cualquier condición dada, cual será la mejor acción. Esto se consigue asociando al espacio de entrada una predicción de la mejor recompensa futura obtenida para cada acción posible.

Entonces, dado un estado que representa el entorno, se buscan las reglas cuya condición coincide, y de ellas se toma la acción que ofrece mejor recompensa futura.

La tarea no es fácil, los algoritmos formales de aprendizaje por refuerzo, necesitan a priori un conocimiento determinista de las posibles entradas y las transiciones resultantes de las acciones, dejando poco o nada para la búsqueda y aplicación de generalización.

Con XCS este problema se resuelve introduciendo algunos ajustes a la componente genética. La idea general es básicamente repartir los recursos (reglas) para que representen todo el espacio con la mayor precisión y generalización posible. Como no es algo que se pueda resumir en unas pocas líneas, aquí os dejo la presentación: