Comparisons of age estimated with isochrone fitting (τ_ISO) in Sect. 4.1 and age derived by our neural network model (τ_NN) using LAMOST spectra for 3103 RGB (left panel) and RC (right panel) stars common to LAMOST and Kepler (testing sample: red dots – 1610 RGBs, 615 RCs, and training sample: black dots – 1493 RGBs, 2499 RCs). The µ and σ are the mean and standard deviations of (τ_IS0 – τ_NN)/τ_IS0, as marked in the bottom-right corner of each panel.