Most of State-of-the-art QA models are mainly based on Convolution Neural Network (CNN), Recurrent Neural Network (RNN) and many variants thereof (Wang and Nyberg, 2015;Yang et al., 2016;Hu et al., 2014;Tan et al., 2015).
with opaque structures of convolutional kernels and recurrent cells, these models are hard to understand for humans.