Auto-encoder -Pre-training DNN Greedy Layer-wise Pre-training again output 1000 a2 合 W3 500 500 合 合w 1000 1000 a2 合 fix合w2 1000 1000 合 fixW1 Input 784 Input 784 XAuto-encoder – Pre-training DNN • Greedy Layer-wise Pre-training again Target 784 1000 1000 10 Input output Input 784 1000 W1 1000 fix 𝑥 𝑎 1 𝑎 ො 2 W2 fix 𝑎 2 1000 W3 500 500 W3 ’