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March 2016

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Mainstream Media

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1997

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Ing cup 1985 – 2000 (up to 1,400,000$) (1985-2000)

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5d win 1998

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October 2015

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“This is the first time that a computer program has defeated a human professional player in the full-sized game of Go, a feat previously thought to be at least a decade away.” Silver, D. et al., 2016. Mastering the game of Go with deep neural networks and tree search. Nature, 529(7587), p.484-489. January 2016

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What did AlphaGo do to beat the strongest human Go player? Tobias Pfeiffer @PragTob pragtob.info

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Go

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Computational Challenge

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Monte Carlo Method

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Neural Networks

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Revolution with Neural Networks

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What did we learn?

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Go

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Computational Challenge

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Go vs. Chess

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Complex vs. Complicated

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„While the Baroque rules of chess could only have been created by humans, the rules of go are so elegant, organic, and rigorously logical that if intelligent life forms exist elsewhere in the universe, they almost certainly play go.“ Edward Lasker (chess grandmaster)

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Larger board 19x19 vs. 8x8

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Almost every move is legal

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Average branching factor: 250 vs 35

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State Space Complexity: 10171 vs 1047

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1080

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Global impact of moves

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6 8 9 5 7 9 6 6 3 5 4 7 6 5 6 8 5 7 6 6 3 4 5 8 5 7 6 3 5 5 6 3 6 MAX MIN MAX MIN MAX Traditional Seach

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6 8 9 5 7 9 6 6 3 5 4 7 6 5 6 8 5 7 6 6 3 4 5 8 5 7 6 3 5 5 6 3 6 MAX MIN MAX MIN MAX Evaluation Function

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Monte Carlo Method

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What is Pi?

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How do you determine Pi?

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2006

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Browne, Cb, and Edward Powley. 2012. A survey of monte carlo tree search methods. Intelligence and AI 4, no. 1: 1-49

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2/4 1/1 0/1 1/1 0/1 A1 D5 F13 C7

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2/4 1/1 0/1 1/1 0/1 A1 D5 F13 C7 Selection

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2/4 1/1 0/1 1/1 0/1 A1 D5 F13 C7 0/0 B5 Expansion

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2/4 1/1 0/1 1/1 0/1 A1 D5 F13 C7 0/0 B5 Simulation

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Random

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Not Human like?

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3/5 2/2 0/1 1/1 0/1 A1 D5 F13 C7 1/1 B5 Backpropagation

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3/5 2/2 0/1 1/1 0/1 A1 D5 F13 C7 1/1 B5 Perspective

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2/5 1/2 0/1 1/1 0/1 A1 D5 F13 C7 1/1 B5 Perspective

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Multi Armed Bandit

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Multi Armed Bandit Exploitation vs Exploration

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wins visits +explorationFactor √ln(totalVisits) visits

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15042 86/193 0/1 1/2 0/2 36/1116 2/2 58/151 1/2 0/2 3/3

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15042 86/193 0/1 1/2 0/2 36/1116 2/2 58/151 1/2 0/2 3/3

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15042 86/193 0/1 1/2 0/2 36/1116 2/2 58/151 1/2 0/2 3/3

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Generate a valid random move

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Who has won?

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General Game Playing

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Anytime

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Lazy

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Expert Knowledge

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Neural Networks

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2014

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What does this even mean?

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Neural Networks

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Input “Hidden” Layer Output Neural Networks

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Weights

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Bias/Threshold

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4 2 -3 3.2 Activation

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5.2 >= 4 2 -3 3.2 Activation

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2.2 <= 4 2 -3 3.2 Activation

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Activation

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Training

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Adjust parameters

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Supervised Learning Input Expected Output

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Backpropagation

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Data set

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Training data + test data

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Training

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Verify

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Overfitting

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Deep Neural Networks

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Convolutional Neural Networks

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Local Receptive Field

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Feature Map

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Stride

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Shared weights and biases

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19 x 19 3 x 17 x 17 Multiple Feature maps/filters

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Architecture ... Input Features 12 layers with 64 – 192 filters Output

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Architecture ... Input Features 12 layers with 64 – 192 filters Output

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Architecture ... Input Features 12 layers with 64 – 192 filters Output

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2.3 million parameters 630 million connections

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● Stone Colour x 3 ● Liberties x 4 ● Liberties after move played x 6 ● Legal Move x 1 ● Turns since x 5 ● Capture Size x 7 ● Ladder Move x 1 ● KGS Rank x 9 Input Features

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Training on game data predicting the next move

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55% Accuracy

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Mostly beats GnuGo

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Combined with MCTS in the Selection

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Asynchronous GPU Power

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Revolution

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Silver, D. et al., 2016. Mastering the game of Go with deep neural networks and tree search. Nature, 529(7587), p.484-489. Networks in Training

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Silver, D. et al., 2016. Mastering the game of Go with deep neural networks and tree search. Nature, 529(7587), p.484-489. Networks in Training

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Silver, D. et al., 2016. Mastering the game of Go with deep neural networks and tree search. Nature, 529(7587), p.484-489. AlphaGo Search

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Selection

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Action Value Prior Probability Visit Count Selection

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Action Value Prior Probability Visit Count

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Action Value Prior Probability Visit Count Selection

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Action Value Prior Probability Visit Count Selection

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0.8 1.2 0.5 1.1 0.9 Action Value + Bonuses

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0.8 1.2 0.5 1.1 0.9 Expansion

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0.8 1.2 0.5 1.1 0.9 Expansion

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0.8 1.2 0.5 1.1 0.9 Prior Probability

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0.8 1.2 0.5 1.1 0.9 Evalution

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0.8 1.2 0.5 1.1 0.9 Evalution

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0.8 1.2 0.5 1.1 0.9 Rollout

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0.8 1.2 0.5 1.1 0.9 Value Network

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0.81 1.3 0.5 1.1 0.9 Backup 1.6

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1202 CPUs 176 GPUS 0.8 1.2 0.5 1.1 0.9

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Tensor

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Human Instinct Policy Network Reading Capability Search Positional Judgement Value Network 3 Strengths of AlphaGo

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Human Instinct Policy Network Reading Capability Search Positional Judgement Value Network Most Important Strength

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More Natural

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Lee Sedol match

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Style

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Game 2

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So when AlphaGo plays a slack looking move, we may regard it as a mistake, but perhaps it should more accurately be viewed as a declaration of victory? An Younggil 8p

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Game 4

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Game 4

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Game 4

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What can we learn?

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Making X faster vs Doing less of X

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Benchmark everything

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Solving problems the human way vs Solving problems the computer way

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Don't blindly dismiss approaches as infeasible

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One Approach vs Combination of Approaches

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Joy of Creation

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PragTob/Rubykon

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pasky/michi

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What did AlphaGo do to beat the strongest human Go player? Tobias Pfeiffer @PragTob pragtob.info

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Sources ● Maddison, C.J. et al., 2014. Move Evaluation in Go Using Deep Convolutional Neural Networks. ● Silver, D. et al., 2016. Mastering the game of Go with deep neural networks and tree search. Nature, 529(7587), p.484-489. ● Michael A. Nielsen, "Neural Networks and Deep Learning", Determination Press, 2015 http://neuralnetworksanddeeplearning.com ● Gelly, S. & Silver, D., 2011. Monte-Carlo tree search and rapid action value estimation in computer Go. Artificial Intelligence, 175(11), p.1856-1876. ● I. Althöfer, “On the Laziness of Monte-Carlo Game Tree Search In Non-tight Situations,” Friedrich-Schiller Univ., Jena, Tech. Rep., 2008. ● Browne, C. & Powley, E., 2012. A survey of monte carlo tree search methods. IEEE Transactions on Intelligence and AI in Games, 4(1), p.1-49. ● Gelly, S. & Silver, D., 2007. Combining online and offline knowledge in UCT. Machine Learning, p.273-280. ● https://www.youtube.com/watch?v=LX8Knl0g0LE&index=9&list=WL

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Photo Credit ● http://www.computer-go.info/events/ing/2000/images/bigcup.jpg ● https://en.wikipedia.org/wiki/File:Kasparov-29.jpg ● http://www.geforce.com/hardware/desktop-gpus/geforce-gtx-titan-black/product-images ● http://giphy.com/gifs/dark-thread-after-lCP95tGSbMmWI ● https://cloudplatform.googleblog.com/2016/05/Google-supercharges-machine-learning-tasks-with-custom-chi p.html ● https://gogameguru.com/i/2016/01/Fan-Hui-vs-AlphaGo-550x364.jpg ● http://makeitstranger.com/ ● CC BY 2.0 – https://en.wikipedia.org/wiki/File:Deep_Blue.jpg – https://www.flickr.com/photos/luisbg/2094497611/ ● CC BY-SA 3.0 – https://en.wikipedia.org/wiki/Alpha%E2%80%93beta_pruning#/media/File:AB_pruning.svg ● CC BY-SA 2.0 – https://flic.kr/p/cPUtny – https://flic.kr/p/dLSKTQ – https://www.flickr.com/photos/83633410@N07/7658272558/

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Photo Credit ● CC BY-NC-ND 2.0 – https://flic.kr/p/q15pzb – https://flic.kr/p/bHSj7D – https://flic.kr/p/ixSsfM – https://www.flickr.com/photos/waxorian/4228645447/ – https://www.flickr.com/photos/pennstatelive/8972110324/ – https://www.flickr.com/photos/dylanstraub/6428496139/ ● https://en.wikipedia.org/wiki/Alphabet_Inc.#/media/File:Alphabet_Inc_Logo_2015.svg ● CC BY 3.0 – https://en.wikipedia.org/wiki/File:Pi_30K.gif