DeepFM (Deep Factorization Machine, proposed by Huawei Noah's Ark Lab and CAS in 2017) is a landmark CTR ranking model that seamlessly integrates low-order explicit feature interactions with high-order deep non-linear representations; it features two parallel branches sharing identical embedding weights: 1) FM Component (Factorization Machine capturing 1st-order linear terms and 2nd-order dot-product interactions
∑i<j⟨vi,vj⟩xixj in
O(kd) linear time); 2) Deep Component (multi-layer feed-forward DNN learning high-order non-linear combinations); final CTR is given by
y^=sigmoid(yFM+yDNN).