Question: what are the state-of-the-art models?
Answer: SVM , CNN , GRU , CNN/GRU+law, r-net , AoA 
Alternative answer: SVM with lexical features in accordance with previous works BIBREF16 , BIBREF17 , BIBREF1 , BIBREF15 , BIBREF4, attention-based method BIBREF3 and other methods we deem important, some off-the-shelf RC models, including r-net BIBREF5 and AoA BIBREF6 , which are the leading models on SQuAD leaderboard