The properties of singular
indices of nonnegative rotation free densities on Ω(λ) = {λ < |z|≦ 1}(λ ≧ 0) will be
studied. The relation between the singular index α(P) of a nonnegative
rotation free density P on Ω(λ)(λ > 0) and the Martin compactification
Ω(λ)P∗ of Ω(λ) with respect to the elliptic equation Δu = Pu will be
established.