Sign Patterns That Allow a Positive or Nonnegative Left Inverse
Sign Patterns That Allow a Positive or Nonnegative Left Inverse
An m by n sign pattern $\mathcal{S}$ is an m by n matrix with entries in $\{+, -, 0 \}$. Such a sign pattern allows a positive (resp., nonnegative) left inverse, provided that there exist an m by n matrix A with the sign pattern $\mathcal{S}$ and an n by …