Artificial Intelligence Introduction to Machine Learning Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee
Introduction Applications which Machine Learning techniques play an important role: Face Recognition Dimensionality Reduction is additionally used for finding important features Face Detection Facial Age Estimation Face recognition Facial age estimation Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 2
Introduction Adaboost structure One of the most popular Machine Learning algorithm for applications with high-variety Good for reducing Detection Time while maintaining Detection Accuracy Often used for Automatic face focusing in Digital Cameras Automatic face focusing Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 3
Introduction Adaboost structure (Facial Age Estimation) Extracting important features those are difficult to be found by Human Building a Model or Property to be learned that maps the facial features to Predicted age Providing theoretical analysis and practical guidelines Extracted features A Model built by Adaboost Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 4
Introduction This is Bigdata era Fast development of technology Burst usage of Internet Lots of Image Sources (Examples) User-created Contents Flickr, Facebook, and YouTube Online source of Images and Texts Explosion of User-created content Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 5
Introduction Power of Machine Learning will be increased because Large amount of accessible data means Large amount of examples for training Large amount of examples for training means Higher chance of accurate learning Higher chance of accurate learning means Valuable but undiscovered knowledge is found Improving utility of Machine Learning Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 6
What is Machine Learning? What is Machine Learning? Difficult to define precisely because it covers a broad range of processes Modification of a behavioral tendency by experience Modification of Behavior by Experience (Data) Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 7
What is Machine Learning? What is Machine Learning? Difficult to define precisely because it covers a broad range of processes Modification of a behavioral tendency by experience Optimizing a performance criterion using example data and past experience Optimizing a performance with regard to a criterion Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 8
What is Machine Learning? Machine Learning Changes in systems for AI tasks: Recognition Diagnosis Planning Robot control Prediction A constant program can never be changed with regard to its environment! Relation to AI Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 9
What is Machine Learning? AI agent Perceives and models its environment Computes proper Actions considering consequences Agent may change its internal process or component according to Perceives and Actions It is regard as a sort of Learning AI agent Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 10
Designing versus Learning There is no need to learn to calculate minimum credit points for graduation Learning is required when: Programming (Designing) versus Machine Learning Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 11
Designing versus Learning There is no need to learn to calculate minimum credit points for graduation Learning is required when: Humans are unable to explain the hidden rule What is the underlying rule? Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 12
Designing versus Learning There is no need to learn to calculate minimum credit points for graduation Learning is required when: Humans are unable to explain the hidden rule Guessing the rule based on a large number of examples Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 13
Designing versus Learning There is no need to learn to calculate minimum credit points for graduation Learning is required when: Humans are unable to explain the hidden rule Extracting hidden relationship Extracting underlying mapping relationship Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 14
Designing versus Learning There is no need to learn to calculate minimum credit points for graduation Learning is required when: Humans are unable to explain the hidden rule Extracting hidden relationship Adapting unknown environment Navigation in unknown environment Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 15
Designing versus Learning There is no need to learn to calculate minimum credit points for graduation Learning is required when: Humans are unable to explain the hidden rule Extracting hidden relationship Adapting unknown environment Too many examples are given Big Data Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 16
Designing versus Learning There is no need to learn to calculate minimum credit points for graduation Learning is required when: Humans are unable to explain the hidden rule Extracting hidden relationship Adapting unknown environment Too many examples are given Dynamic environment Dynamic environment: Weather forecasting Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 17
Relationships with Other Disciplines Machine Learning unifies several disciplines Relation to other disciplines Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 18
Relationships with Other Disciplines Machine Learning unifies several disciplines Statistics Guessing unknown probability distribution Making decisions based on estimated new samples Machine Learning versus Statistics Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 19
Relationships with Other Disciplines Machine Learning unifies several disciplines Statistics Brain Models Simplified models of biological neurons Approximating the learning phenomena Popular example: Artificial Neural Network Brain modeling Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 20
Relationships with Other Disciplines Machine Learning unifies several disciplines Statistics Brain Models Adaptive Control Theory Controlling a processing having parameters that must be estimated during operation Popular example: Robot Task-adaptive Robotic Arm Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 21
Relationships with Other Disciplines Machine Learning unifies several disciplines Statistics Brain Models Adaptive Control Theory Psychological Models Studying the performance of living organism in various learning tasks Popular example: Reinforcement Learning Reinforcement Learning Procedure Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 22
Relationships with Other Disciplines Machine Learning unifies several disciplines Statistics Brain Models Adaptive Control Theory Psychological Models Evolutionary Models Mimic the evolution of species Adaptation of Finch w.r.t. its environment or behavior Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 23
Relationships with Other Disciplines Machine Learning unifies several disciplines Statistics Brain Models Adaptive Control Theory Psychological Models Evolutionary Models Mimic the evolution of species Popular example: Genetic Algorithm Genetic Algorithm Procedure Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 24
Relationships with Other Disciplines Machine Learning unifies several disciplines Statistics Brain Models Adaptive Control Theory Psychological Models Evolutionary Models Modeling and Optimization How to model the separating boundary and optimize the performance Class separation Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 25
Relationships with Other Disciplines Machine Learning unifies several disciplines Statistics Brain Models Adaptive Control Theory Psychological Models Evolutionary Models Modeling and Optimization Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 26
Universal Dataset Universal set Containing all the possible data pairs There is a unknown probability distribution Universal set Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 27
Universal Dataset Universal set Containing all the possible data pairs There is a unknown probability distribution Training set Only a subset of universal set is possibly considered due to limited memory or time This subset is known as Training set Universal set Training set Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 28
Universal Dataset Training set Only a subset of universal set is possibly considered due to limited memory or time This subset is known as Training set Independently and Identically Distributed (i.i.d.) Validation set A subset of training set for monitoring the training process of Machine Learning algorithm Dataset Preparation Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 29
What Are We Looking For? Possible learned properties A line separating boundary between two groups A relation among examples Test set Unseen samples or future events A disjoint set of Training set and Validation set Used for examining performance evaluation Dataset Preparation Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 30
What Are We Looking For? Universal set Assumed to exist but unknown Training set A subset of Universal set that is obtained from Data acquisition stage Example of three labeled datasets: Universal, Training, and Test Set Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 31
What Are We Looking For? Universal set Assumed to exist but unknown Training set A subset of Universal set that is obtained from Data acquisition stage Test set A set used for examining the performance Training set Test set Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 32
No Free Lunch Rule Possible learned properties (Revisited) A line separating boundary between two groups A relation among examples No Free Lunch Rules Assumptions that making Machine Learning feasible Assumptions needed for both Dataset and Properties Can we expect any classification method to be superior or inferior overall? The answer is NO Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 33
No Free Lunch Rule Assumptions needed for Dataset Training set and Test set are come from the same distribution Assumptions needed for Properties Making assumptions on what kind of function to learn How to model the property Can we expect any classification method to be superior or inferior overall? The answer is NO Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 34
No Free Lunch Rule Assumptions needed for Dataset Training set and Test set are come from the same distribution Assumptions needed for Properties Making assumptions on what kind of function to learn Straight line vs. Curved line How to model the property Gaussian distribution vs. Poisson distribution Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 35
Learning Input-Output Functions = ( ): A short summarization of Machine Learning : Vector-valued input or Training set Ξ or h( ): Predicted output : hypothesis function between and Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 36
Learning Input-Output Functions = ( ): A short summarization of Machine Learning : Vector-valued input or Training set Ξ or h( ): Predicted output : hypothesis function between and H: Set of all possible hypothesis functions Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 37
Types of Learning Types of Machine Learning Supervised Learning Unsupervised Learning Semi-supervised Learning Reinforcement Learning Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 38
Types of Learning: Supervised Learning Types of Machine Learning Supervised Learning Learning from labeled dataset Find the relationships between the Feature set and the Label set Find a hypothesis h that is mostly-agreed by members of Training set Ξ Hypothesis If it Walks/Swims/Quacks like a Duck Then It must be a Duck Features: Walks, Swims, Quacks Label: Ducks, Not ducks Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 39
Types of Learning: Supervised Learning Types of Machine Learning Supervised Learning Learning from labeled dataset Find the relationships between the Feature set and the Label set Find a hypothesis h that is mostly-agreed by members of Training set Ξ Regression: finding a curve that fits points Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 40
Types of Learning: Supervised Learning Types of Machine Learning Supervised Learning Learning from labeled dataset Find the relationships between the Feature set and the Label set Find a hypothesis h that is mostly-agreed by members of Training set Ξ Regression: finding a curve that fits points Classification: finding a discriminating vector(s) Figure (a) Figure (b) Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 41
Types of Learning: Unsupervised Learning Types of Machine Learning Supervised Learning Unsupervised Learning Learning from characteristics of dataset Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 42
Types of Learning: Unsupervised Learning Types of Machine Learning Supervised Learning Unsupervised Learning Learning from intrinsic characteristics of dataset Popular purposes Clustering, Probability density estimation, Finding association among features, Dimensionality reduction Output can be used for other learning paradigms Figure (a) Figure (b) Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 43
Types of Learning: Semi-supervised Learning Types of Machine Learning Supervised Learning Unsupervised Learning Semi-supervised Learning Learning with the dataset containing both labeled and unlabeled data Figure (a) Figure (b) Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 44
Types of Learning: Reinforcement Learning Types of Machine Learning Supervised Learning Unsupervised Learning Semi-supervised Learning Reinforcement Learning Learning from rewards or mistakes Agent acts in an Environment Reinforcement Learning procedure Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 45
Input Vectors Input vectors Pattern/feature vectors, samples, examples, instances An example dataset Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 46
Input Vectors Input vectors Pattern/feature vectors, samples, examples, instances Features: the components of the input vector Attributes, input variables, components An example dataset Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 47
Input Vectors Input vectors Pattern/feature vectors, samples, examples, instances Features: the components of the input vector Attributes, input variables, components An instance of (class, major, sex, advisor) can be (sophomore, history, male, Higgins) An example dataset Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 48
Input Vectors Input vectors Pattern/feature vectors, samples, examples, instances Features: the components of the input vector Attributes, input variables, components An instance of (class, major, sex, advisor) can be (sophomore, history, male, Higgins) Boolean valued-features Boolean feature (High, Normal) An example dataset Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 49
Outputs Outputs Output value, label, class, category, decision Function estimator if output is a real number Classifier if output is a categorical value Application: hand-written character recognition Input: printed character Output: categories of hand-written character An example dataset Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 50
Outputs Outputs Output value, label, class, category, decision Function estimator if output is a real number Classifier if output is a categorical value Vector-valued outputs If mutually exclusive then Multi-class problem If not then Multi-label problem An example dataset Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 51
Outputs Outputs Output value, label, class, category, decision Function estimator if output is a real number Classifier if output is a categorical value Vector-valued outputs Boolean outputs True: positive instance False: negative instance An example dataset Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 52
Outputs Outputs Output value, label, class, category, decision Function estimator if output is a real number Classifier if output is a categorical value Vector-valued outputs Boolean outputs Concept learning: Boolean input-output An example dataset Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 53
Preprocessing Preprocessing steps for a desired Machine Learning Standard Machine Learning Procedure Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 54
Noise and Outliers Preprocessing steps for a desired Machine Learning Noise and Outliers Corrupted values leading to Outliers An example of outlier Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 55
Noise and Outliers Preprocessing steps for a desired Machine Learning Noise and Outliers Corrupted values leading to Outliers Class noise and Attribute noise Class noise vs. Attribute noise Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 56
Missing Value Preprocessing steps for a desired Machine Learning Noise and Outliers Missing value Adding median/mean values Deleting corresponding row Using the value from the previous row Example of missing value Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 57
Scaling Preprocessing steps for a desired Machine Learning Noise and Outliers Missing value Scaling Reducing values in columns into a common scale Normalization or Standardization Normalization Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 58
Natural Language Processing for Texts Preprocessing steps for a desired Machine Learning Noise and Outliers Missing value Scaling Natural Language Processing for Texts Encoding free texts to vectors Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 59
Imbalanced Datasets Preprocessing steps for a desired Machine Learning Noise and Outliers Missing value Scaling Natural Language Processing for Texts Imbalanced datasets Class distribution is skewed Scatter plot of Imbalanced dataset Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 60
Imbalanced Datasets Preprocessing steps for a desired Machine Learning Noise and Outliers Missing value Scaling Natural Language Processing for Texts Imbalanced datasets Class distribution is skewed Over-/Under-sampling Synthesizing examples Over-/Under-sampling Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 61
Training Main step of Machine Learning Machine Learning procedures Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 62
Policy Main step of Machine Learning Training policy Batch method Entire Training set is available Use all at once to compute the function Batch Machine Learning Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 63
Policy Main step of Machine Learning Training policy Batch method Online method Arriving one member of Training set at a time Optimizing the function incrementally Deciding a next action based on current action Online Machine Learning Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 64
Feature Selection Main step of Machine Learning Training policy Feature selection Not all features contribute to the learning! One of Model Selection Approaches Can be used for improve the performance Curse of dimensionality Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 65
Evaluation Main step of Machine Learning Training policy Feature selection Evaluation Evaluating learning performance Usage of evaluation metrics Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 66
Evaluation Main step of Machine Learning Training policy Feature selection Evaluation Evaluating learning performance Population evaluation metric Mean-squared-error for Regression task Accuracy: the total number of errors Confusion matrix for calculating Accuracy Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 67
Parameter Tuning Main step of Machine Learning Training policy Feature selection Evaluation Parameter tuning Controlling learning model Popular approach: Trial-and-error basis Parameter tuning based on Trial-and-error strategy Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 68
Overfitting (Bias) Main step of Machine Learning Training policy Feature selection Evaluation Parameter tuning Overfitting Good on Training set, but poor on Test set Overfit vs. Underfit Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 69
Underfitting (Variance) Main step of Machine Learning Training policy Feature selection Evaluation Parameter tuning Overfitting Underfitting Low performance on both sets Overfit vs. Underfit Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 70
Bias and Variance Trade-off Main step of Machine Learning Training policy Feature selection Evaluation Parameter tuning Overfitting Underfitting Low performance on both sets Overfit vs. Underfit Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 71
Model Stacking Main step of Machine Learning Training policy Feature selection Evaluation Parameter tuning Overfitting Underfitting Model stacking Combining multiple algorithms Example of model stacking Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 72
Sample Applications Sample applications based on Machine Learning Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 73
Sample Applications Sample applications based on Machine Learning Rule discovery for printing industry problem Electric power load forecasting Automatic help desk assistant 3D printing rule discovery Electric power load forecasting Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 74
Sample Applications Sample applications based on Machine Learning Rule discovery for printing industry problem Electric power load forecasting Automatic help desk assistant Planning and scheduling for a steel mill Stars and galaxies classification Stars and galaxies Classification Steel mill planning Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 75
Sample Applications Successes of Machine Learning in real world Sharp s Japanese Kanji character recognition system 200 characters per second with 99% accuracy Fujitsu s continuous steel casting monitoring system Kanji character recognition Steel casting monitoring Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 76
Sample Applications Successes of Machine Learning in real world Sharp s Japanese Kanji character recognition system 200 characters per second with 99% accuracy Fujitsu s continuous steel casting monitoring system Artificial Intelligence Chung-Ang University Narration: Prof. Jaesung Lee 77