Marianna Bolla

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Asymptotic behavior of the singular value decomposition (SVD) of blown up matrices and normalized blown up contingency tables exposed to Wigner-noise is investigated. It is proved that such an m × n matrix almost surely has a constant number of large singular values (of order √ mn), while the rest of the singular values are of order √ m + n as m, n → ∞.(More)
The notion of the Laplacian of weighted graphs will be introduced, the eigenvectors belonging to k consecutive eigen-values of which define optimal k-dimensional Euclidean representation of the vertices. By means of these spectral techniques some combinatorial problems concerning minimal (k+ 1)-cuts of weighted graphs can be handled easily with linear(More)
The role of the normalized modularity matrix in finding homogeneous cuts will be presented. We also discuss the testability of the structural eigenvalues and that of the subspace spanned by the corresponding eigenvectors of this matrix. In the presence of a spectral gap between the k − 1 largest absolute value eigenvalues and the remainder of the spectrum,(More)
Testable weighted graph parameters and equivalent notions of testability – proved in [4] for simple graphs – are generalized for vertex-and edge-weighted graphs with no dominant vertex-weights. We prove that certain balanced minimum multiway cut densities are testable. Using this fact, quadratic programming techniques are applied to approximate some of(More)
Factors, obtained by correspondence analysis, are used to find biclustering of a contingency table such that the row–column cluster pairs are regular, i.e., they have small discrepancy. In our main theorem, the constant of the so-called volume-regularity is related to the SVD of the normalized contingency table. This result is applicable to two-way cuts(More)
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