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.