A SPECIAL PROPERTY OF RESISTANCE MATRICES.

We deduce a new property exhibited by the resistance matrices of connected graphs. Specifically, we show that if R=(r_ij) is the resistance matrix of a connected graph on n vertices, then every off-diagonal entry in the Moore-Penrose inverse of ... is negative. Thus, we establish that the Moore-Penrose inverse of the resistance Laplacian matrices are M-matrices. [ABSTRACT FROM AUTHOR]