Diagram of log(N/O) vs. 12+log(O/H) for the HII regions in our sample of LINERs. The colorbar shows the distance to the galactic center in terms of R₅₀. Nuclear estimations of the corresponding chemical abundance ratio are represented as follows: green triangles are the estimations from AGN models with α_OX = −1.6; orange and red stars are the estimations from pAGB models with T_eff = 10⁵ K and T_eff = 1.5 ⋅ 10⁵ K respectively; and black squares are the estimations from ADAF models. The solid back line represents the fit provided by Coziol et al. (1999), the dotted line shows the fit by Andrews & Martini (2013), and the dash-dotted line shows the fit by (Belfiore et al. 2015).