Highway Networks and Residual Networks Renjie Liao University of Toronto Jan 26, 2016 Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 1 / 23
Neural Network A network connecting numerous neurons Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 2 / 23
Neural Network A network connecting numerous neurons Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 2 / 23
Analogy Imagine a neural network as a map Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 3 / 23
Analogy Imagine a neural network as a map Imagine a neuron as a place Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 3 / 23
Analogy Imagine a neural network as a map Imagine a neuron as a place Imagine yourself as the information flow Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 3 / 23
Analogy Imagine a neural network as a map Imagine a neuron as a place Imagine yourself as the information flow Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 3 / 23
Analogy Suppose you (information flow) wants to reach Bakery (neuron B) from City Hall (neuron A), what will you do? Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 4 / 23
Analogy Suppose you (information flow) wants to reach Bakery (neuron B) from City Hall (neuron A), what will you do? You have to follow the path of network! Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 4 / 23
Analogy Suppose you (information flow) wants to reach Bakery (neuron B) from City Hall (neuron A), what will you do? You have to follow the path of network! What if there is a highway connecting Bakery and City Hall directly? Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 4 / 23
Highway Networks Allowing direct pass (highway) between neurons in different layers. Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 5 / 23
Highway Networks Allowing direct pass (highway) between neurons in different layers. Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 5 / 23
Highway Networks Original network: �� � w 1 z 1 = σ n x n + b (1) n =1 Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 6 / 23
Highway Networks Original network: �� � w 1 z 1 = σ n x n + b (1) n =1 Highway network: �� � w 1 z 1 = T σ n x n + b + (1 − T ) x 1 (2) n =1 Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 6 / 23
Highway Networks Original network: �� � w 1 z 1 = σ n x n + b (1) n =1 Highway network: �� � w 1 z 1 = T σ n x n + b + (1 − T ) x 1 (2) n =1 Gating function: �� � T = σ w ′ n x n + b ′ (3) n =1 Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 6 / 23
Highway Networks Remember the shape of sigmoid function. Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 7 / 23
Highway Networks Remember the shape of sigmoid function. Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 7 / 23
Highway Networks Remember the shape of sigmoid function. We can set bias b ′ to negative values such that gating value T → 0. Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 7 / 23
Benefits of Highway networks Enable training of very deep neural networks (e.g., hundreds of layers) “Srivastava, R.K., Greff, K. and Schmidhuber, J., 2015. Highway Networks. arXiv preprint arXiv:1505.00387”. Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 8 / 23
Benefits of Highway networks Enable training of very deep neural networks (e.g., hundreds of layers) “Srivastava, R.K., Greff, K. and Schmidhuber, J., 2015. Highway Networks. arXiv preprint arXiv:1505.00387”. Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 9 / 23
Residual Networks Motivation: Does depth matter for deep learning? Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 10 / 23
Residual Networks Motivation: Does depth matter for deep learning? “He, K., Zhang, X., Ren, S. and Sun, J., 2015. Deep Residual Learning for Image Recognition. arXiv preprint arXiv:1512.03385”. Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 10 / 23
Residual Networks Motivation: Does depth matter for deep learning? “He, K., Zhang, X., Ren, S. and Sun, J., 2015. Deep Residual Learning for Image Recognition. arXiv preprint arXiv:1512.03385”. Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 11 / 23
Residual Networks We need new architecture to make depth matter. Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 12 / 23
Residual Networks We need new architecture to make depth matter. Suppose you have a plain 2-layer network H . “He, K., Zhang, X., Ren, S. and Sun, J., 2015. Deep Residual Learning for Image Recognition. arXiv preprint arXiv:1512.03385”. Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 12 / 23
Residual Networks We need new architecture to make depth matter. Suppose you have a plain 2-layer network H . We use a new building block which forces the previous 2-layer F to learn the residual H − x . Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 13 / 23
Residual Networks We need new architecture to make depth matter. Suppose you have a plain 2-layer network H . We use a new building block which forces the previous 2-layer F to learn the residual H − x . “He, K., Zhang, X., Ren, S. and Sun, J., 2015. Deep Residual Learning for Image Recognition. arXiv preprint arXiv:1512.03385”. Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 13 / 23
Residual Networks What we have done? Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 14 / 23
Residual Networks What we have done? Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 14 / 23
Residual Networks What we have done? “He, K., Zhang, X., Ren, S. and Sun, J., 2015. Deep Residual Learning for Image Recognition. arXiv preprint arXiv:1512.03385”. Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 14 / 23
Residual Networks Based on this building block, we can do some crazy things like... Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 15 / 23
Residual Networks Based on this building block, we can do some crazy things like... “He, K., Zhang, X., Ren, S. and Sun, J., 2015. Deep Residual Learning for Image Recognition. arXiv preprint arXiv:1512.03385”. Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 15 / 23
Image Net Challenge Results “He, K., Zhang, X., Ren, S. and Sun, J., 2015. Deep Residual Learning for Image Recognition. arXiv preprint arXiv:1512.03385”. Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 16 / 23
PASCAL VOC Challenge Results “He, K., Zhang, X., Ren, S. and Sun, J., 2015. Deep Residual Learning for Image Recognition. arXiv preprint arXiv:1512.03385”. Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 17 / 23
More Results “He, K., Zhang, X., Ren, S. and Sun, J., 2015. Deep Residual Learning for Image Recognition. arXiv preprint arXiv:1512.03385”. Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 18 / 23
More Results “He, K., Zhang, X., Ren, S. and Sun, J., 2015. Deep Residual Learning for Image Recognition. arXiv preprint arXiv:1512.03385”. Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 19 / 23
More Results “He, K., Zhang, X., Ren, S. and Sun, J., 2015. Deep Residual Learning for Image Recognition. arXiv preprint arXiv:1512.03385”. Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 20 / 23
More Results “He, K., Zhang, X., Ren, S. and Sun, J., 2015. Deep Residual Learning for Image Recognition. arXiv preprint arXiv:1512.03385”. Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 21 / 23
More Results “He, K., Zhang, X., Ren, S. and Sun, J., 2015. Deep Residual Learning for Image Recognition. arXiv preprint arXiv:1512.03385”. Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 22 / 23
Thanks! Renjie Liao (UofT) Highway Networks and Residual Networks Jan 26, 2016 23 / 23
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