Dusting my Ph.D. thesis off

After attending Albert Orriols’s Ph.D. thesis defense, I ended wondering how many of the question I posted in mine have not been solved. The answer, quite a bit. So, I just decided to dig it up, and put it up here. Yes, the thesis was not written in English (in those days my fellowship had some strings attached), but math formulation, graphs, and results are readable in any language ;) Also, GALE was written and documented in english, and is available here. ...

Dec 30, 2008 · 2 min · 255 words · Xavier Llorà

Meandre: Semantic-Driven Data-Intensive Flows in the Clouds

by Llorà, X., Ács, B., Auvil, L., Capitanu, B., Welge, M.E., Goldberg, D.E. (2008). This paper has been accepted at the 4th IEEE International Conference on e-Science. An early draft of the paper can be found as IlliGAL technical report 2008013. You can download the pdf here. More information is also available at the Meandre website as part of the SEASR project. Abstract: Data-intensive flow computing allows efficient processing of large volumes of data otherwise unapproachable. This paper introduces a new semantic-driven data-intensive flow infrastructure which: (1) provides a robust and transparent scalable solution from a laptop to large-scale clusters,(2) creates an unified solution for batch and interactive tasks in high-performance computing environments, and (3) encourages reusing and sharing components. Banking on virtualization and cloud computing techniques the Meandre infrastructure is able to create and dispose Meandre clusters on demand, being transparent to the final user. This paper also presents a prototype of such clustered infrastructure and some results obtained using it. ...

Nov 15, 2008 · 1 min · 162 words · Xavier Llorà

Analyzing Trends in the Blogosphere Using Human-Centered Analysis and Visualization Tools

by Xavier Llorà, Noriko Imafuji Yasui, David E. Goldberg (2006). Proceedings of the International Conference on Weblogs and Social Mining (ICWSM 2007). Also as IlliGAL TR. No. 2006026. Link to the PDF. Abstract The blogsphere is a valuable source of information. From simple topic analysis in the blogosphere—what’s hot—to harvesting and analyzing valuable market trends—what product and features are suggested—require a tight integration of computer- and human-based analysis capabilities. Computers can easily assist the processing filtering and visualizing relevant and key elements of the blogosphere, but coupling them with human evaluation and reasoning can provide the final steps to connect pieces of relevant information into better description map of the current trends of the blogosphere. An example of the need for such human-centered analysis was David R. Ellis’ film Snakes on a Plane (2006) which failed to properly translate blogosphere discussions into a successful commercial product—as a clear misalignment of both environments the blogsphere and the final targeted market. In this paper, we present some human-centered visualization and analysis tools that can help users to compare and reason synergies and misalignments revolving around a particular topic. ...

Mar 26, 2007 · 1 min · 186 words · Xavier Llorà

Communication gap management for fertile community

by Naohiro Matsumura, David E. Goldberg, and Xavier Llorà (2006). Journal of Soft Computing, Volume 11 , Issue 8, pp. 791–798, ACM press. Link to the ACM portal. Initial work also available as IlliGAL TR No 2005001. Abstract In the paper, we first present an approach to extract social networks from message boards on the Internet. Then we propose communication gaps based on structural features of the social networks as an indicator of understanding the state of communication. After we classify 3,000 social networks into three types of communication, i.e., interactive communication, distributed communication, and soapbox communication, we suggest communication gap management to identify the types of communication, the roles of individuals, and important ties, all of which can be used for drawing up a plan for realizing fertile community. ...

Mar 24, 2007 · 1 min · 130 words · Xavier Llorà

Toward routine billion-variable optimization using genetic algorithms

by Goldberg, D. E., Sastry, K., and Llorà X. (2007). Complexity, 12(3), 27—29. Link to the PDF. Abstract: The push for better understanding and design of complex systems requires the solution of challenging optimization problems with large numbers of decision variables. This note presents principled results demonstrating the scalable solution of a difficult test function on instances over a billion variables using a parallel implementation of a genetic algorithm (GA). The problem addressed is a noisy, blind problem over a vector of binary decision variables. Noise is added equaling a tenth of the deterministic objective function variance of the problem, thereby making it difficult for simple hillclimbers to find the optimal solution. The genetic algorithm used - the compact GA - is able to find the optimum in the presence of noise quickly, reliably, and accurately, and the solution scalability follows known convergence theories. These results on noisy problem together with other results on problems involving varying modularity, hierarchy, and overlap foreshadow routine solution of billion-variable problems across the landscape of complexity science. ...

Jan 18, 2007 · 1 min · 173 words · Xavier Llorà