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In this paper we address the problem of identifying differences between populations of trees. Besides the theoretical relevance of this problem, we are interested in testing if trees characterizing protein sequences from different families constitute samples of significantly different distributions. In this context, trees are obtained by modelling protein… (More)
Efficient automatic protein classification is of central importance in genomic annotation. As an independent way to check the reliability of the classification, we propose a statistical approach to test if two sets of protein domain sequences coming from two families of the Pfam database are significantly different. We model protein sequences as… (More)
We study Cantor Staircases in physics that have the Farey-Brocot arrangement for the Q P rational heights of stability intervals I(Q P), and such that the length of I(Q P) is a convex function of 1 P. Circle map staircases and the magnetization function fall in this category. We show that the fractal sets Ω underlying these staircases are connected with key… (More)
A " coupling from the past " construction of the Gibbs sampler process is used to perfectly simulate a random vector in a box B, a Cartesian product of bounded intervals. An algorithm to sample vectors with multinormal distribution truncated to B is implemented.
The study of community structure has been a hot topic of research over the last years. But, while successfully applied in several areas, the concept lacks of a general and precise notion. Facts like the hierarchical structure and heterogeneity of complex networks make it difficult to unify the idea of community and its evaluation. The global functional… (More)
Let a < b, Ω = [a, b] Z d and H be the (formal) Hamiltonian defined on Ω by H(η) = 1 2 x,y∈Z d J(x − y) (η(x) − η(y)) 2 (1) where J : Z d → R is any summable non-negative symmetric function (J(x) ≥ 0 for all x ∈ Z d , x J(x) < ∞ and J(x) = J(−x)). We prove that there is a unique Gibbs measure on Ω associated to H. The result is a consequence of the fact… (More)
The Internet is composed of routing devices connected between them and organized into independent administrative entities: the Autonomous Systems. The existence of different types of Autonomous Systems (like large connectivity providers, Internet Service Providers or universities) together with geographical and economical constraints, turns the Internet… (More)