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Andrés M. Encinas

Publications and source records attributed to Andrés M. Encinas.

6 recordsLinked to original sources
arXiv2026

The $M$-matrix group inverse problem for recoverable complete networks

This study investigates the conditions under which the group inverse of a singular, irreducible, symmetric $M$-matrix retains the $M$-matrix property. By concentrating on a structured subclass derived from rank-one perturbations of a diagonal matrix, and inspired by recoverable complete networks, we obtain explicit analytical results. Utilizing both matrix-theoretic methodologies and potential theory on networks, we establish necessary and sufficient conditions for the $M$-property of the specified network in terms of conductances and associated Doob potentials. This framework facilitates the construction of families of singular, irreducible $M$-matrices whose group inverses maintain the $M$-matrix structure. Our findings offer novel insights into this research domain and enhance the relationship between $M$-matrix theory and network analysis.

math.GM↗
arXiv2025

A Spectral Approach to Kemeny's Constant

Kemeny's constant quantifies the expected time for a random walk to reach a randomly chosen vertex, providing insight into the global behavior of a Markov chain. We present a novel eigenvector-based formula for computing Kemeny's constant. Moreover, we analyze the impact of network structure on Kemeny's constant. In particular, we use various spectral techniques, such as spectral sparsification of graphs and eigenvalue interlacing, and show that they are particularly useful in this context for deriving approximations and sharp bounds for Kemeny's constant

math.CO↗
arXiv2023

Stable recovery of piecewise constant conductance on spider networks

We address the discrete inverse conductance problem for well-connected spider networks; that is, to recover the conductance function on a well-connected spider network from the Dirichlet-to-Neumann map. It is well-known that this inverse problem is exponentially ill-posed, requiring the implementation of a regularization strategy for numerical solutions. Our focus lies in exploring whether prior knowledge of the conductance being piecewise constant within a partition of the edge set comprising few subsets enables stable conductance recovery. To achieve this, we propose formulating the problem as a polynomial optimization one, incorporating a regularization term that accounts for the piecewise constant hypothesis. We show several experimental examples in which the stable conductance recovery under the aforementioned hypothesis is feasible.

math.CO↗
arXiv2022

The $M$-matrix group inverse problem for distance-biregular graphs

In this paper we provide the group inverse of the combinatorial Laplacian matrix of distance-biregular graphs using the so-called equilibrium measures for sets obtained by deleting a vertex. We also show that the two equilibrium arrays characterizing a distance-biregular graph can be expressed in terms of the mentioned equilibrium measures. As a consequence of the minimum principle, we show a characterization of when the group inverse of the combinatorial Laplacian matrix of a distance-biregular graph is an $M$-matrix.

math.CO↗
arXiv2015

Floquet Theory for Second Order Linear Homogeneous Difference Equations

In this paper we provide a version of the Floquet's theorem to be applied to any second order difference equations with quasi-periodic coefficients. To do this we extend to second order linear difference equations with quasi-periodic coefficients, the known equivalence between the Chebyshev equations and the second order linear difference equations with constant coefficients. So, any second order linear difference equations with quasi-periodic coefficients is essentially equivalent to a Chebyshev equation, whose parameter only depends on the values of the quasi-periodic coefficients and can be determined by a non-linear recurrence. Moreover, we solve this recurrence and obtaining a closed expression for this parameter. As a by-product we also obtain a Floquet's type result; that is, the necessary and sufficient condition for the equation has quasi-periodic solutions.

math.CA↗