SlideShare a Scribd company logo
1 of 22
Download to read offline
Introduction to Machine Learning
Sudeshna Sarkar
IIT Kharagpur
Module 1: Introduction
Part A: Introduction
Overview of Course
1. Introduction
2. Linear Regression and Decision Trees
3. Instance based learning
Feature Selection
4. Probability and Bayes Learning
5. Support Vector Machines
6. Neural Network
7. Introduction to Computational Learning Theory
8. Clustering
Module 1
1. Introduction
a) Introduction
b) Different types of learning
c) Hypothesis space, Inductive Bias
d) Evaluation, Training and test set, cross-validation
2. Linear Regression and Decision Trees
3. Instance based learning
Feature Selection
4. Probability and Bayes Learning
5. Support Vector Machines
6. Neural Network
7. Introduction to Computational Learning Theory
8. Clustering
Machine Learning History
• 1950s:
– Samuel's checker-playing program
• 1960s:
– Neural network: Rosenblatt's perceptron
– Minsky & Papert prove limitations of Perceptron
• 1970s:
– Symbolic concept induction
– Expert systems and knowledge acquisition bottleneck
– Qui la ’s ID3
– Natural language processing (symbolic)
Machine Learning History
• 1980s:
– Advanced decision tree and rule learning
– Learning and planning and problem solving
– Resurgence of neural network
– Valia t’s PAC learning theory
– Focus on experimental methodology
• 90's ML and Statistics
– Data Mining
– Adaptive agents and web applications
– Text learning
– Reinforcement learning
– Ensembles
– Bayes Net learning
• 1994: Self-driving car
road test
• 1997: Deep Blue
beats Gary Kasparov
Machine Learning History
• Popularity of this field in
recent time and the reasons
behind that
– New software/ algorithms
• Neural networks
• Deep learning
– New hardware
• GPU’s
– Cloud Enabled
– Availability of Big Data
• 2009: Google builds self
driving car
• 2011: Watson wins
Jeopardy
• 2014: Human vision
surpassed by ML systems
Programs vs learning algorithms
Algorithmic solution Machine learning solution
Computer
Data Program
Output
Computer
Data Output
Program
Machine Learning : Definition
• Learning is the ability to improve one's behaviour based on
experience.
• Build computer systems that automatically improve with
experience
• What are the fundamental laws that govern all learning
processes?
• Machine Learning explores algorithms that can
– learn from data / build a model from data
– use the model for prediction, decision making or solving
some tasks
Machine Learning : Definition
• A computer program is said to learn from
experience E with respect to some class of
tasks T and performance measure P, if its
performance at tasks in T, as measured by P,
improves with experience E.
[Mitchell]
Components of a learning problem
• Task: The behaviour or task being improved.
– For example: classification, acting in an
environment
• Data: The experiences that are being used to
improve performance in the task.
• Measure of improvement :
– For example: increasing accuracy in prediction,
acquiring new, improved speed and efficiency
Black-box Learner
Experiences
Data
Background knowledge/
Bias
Problem/
Task
Answer/
Performance
Learner
Experiences
Data
Background knowledge/
Bias
Problem/
Task
Answer/
Performance
Learner Reasoner
Models
Many domains and applications
Medicine:
• Diagnose a disease
– Input: symptoms, lab measurements, test results,
DNA tests,
– Output: o e of set of possi le diseases, or o e
of the a o e
• Data: historical medical records
• Learn: which future patients will respond best to
which treatments
Many domains and applications
Vision:
• say what objects appear in an image
• convert hand-written digits to characters 0..9
• detect where objects appear in an image
Many domains and applications
Robot control:
• Design autonomous mobile robots that learn
from experience to
– Play soccer
– Navigate from their own experience
Many domains and applications
NLP:
• detect where entities are mentioned in NL
• detect what facts are expressed in NL
• detect if a product/movie review is positive,
negative, or neutral
Speech recognition
Machine translation
Many domains and applications
Financial:
• predict if a stock will rise or fall
• predict if a user will click on an ad or not
Application in Business Intelligence
• Forecasting product sales quantities taking
seasonality and trend into account.
• Identifying cross selling promotional opportunities
for consumer goods.
• …
Some other applications
• Fraud detection : Credit card Providers
• determine whether or not someone will
default on a home mortgage.
• Understand consumer sentiment based off of
unstructured text data.
• Fore asti g o e ’s o i tio rates ased
off external macroeconomic factors.
Learner
Experiences
Data
Background knowledge/
Bias
Problem/
Task
Answer/
Performance
Learner Reasoner
Models
Design a Learner
Experiences
Data
Background
knowledge/
Bias
Problem/
Task
Answer/
Performance
Learn
er
Reaso
ner
Models
1. Choose the training
experience
2. Choose the target
function (that is to be
learned)
3. Choose how to
represent the target
function
4. Choose a learning
algorithm to infer the
target function
Choosing a Model Representation
• The richer the representation, the more useful
it is for subsequent problem solving.
• The richer the representation, the more
difficult it is to learn.
• Components of Representation
– Features
– Function class / hypothesis language

More Related Content

Similar to Introduction to Machine Learning

ML.pptvdvdvdvdvdfvdfgvdsdgdsfgdfgdfgdfgdf
ML.pptvdvdvdvdvdfvdfgvdsdgdsfgdfgdfgdfgdfML.pptvdvdvdvdvdfvdfgvdsdgdsfgdfgdfgdfgdf
ML.pptvdvdvdvdvdfvdfgvdsdgdsfgdfgdfgdfgdfAvijitChaudhuri3
 
Rahul_Kirtoniya_11800121032_CSE_Machine_Learning.pptx
Rahul_Kirtoniya_11800121032_CSE_Machine_Learning.pptxRahul_Kirtoniya_11800121032_CSE_Machine_Learning.pptx
Rahul_Kirtoniya_11800121032_CSE_Machine_Learning.pptxRahulKirtoniya
 
Machine Learning Contents.pptx
Machine Learning Contents.pptxMachine Learning Contents.pptx
Machine Learning Contents.pptxNaveenkushwaha18
 
Machine learning basics by akanksha bali
Machine learning basics by akanksha baliMachine learning basics by akanksha bali
Machine learning basics by akanksha baliAkanksha Bali
 
Machine learning basics
Machine learning basics Machine learning basics
Machine learning basics Akanksha Bali
 
Introduction to ML (Machine Learning)
Introduction to ML (Machine Learning)Introduction to ML (Machine Learning)
Introduction to ML (Machine Learning)SwatiTripathi44
 
Machine Learning: Applications, Process and Techniques
Machine Learning: Applications, Process and TechniquesMachine Learning: Applications, Process and Techniques
Machine Learning: Applications, Process and TechniquesRui Pedro Paiva
 
Building High Available and Scalable Machine Learning Applications
Building High Available and Scalable Machine Learning ApplicationsBuilding High Available and Scalable Machine Learning Applications
Building High Available and Scalable Machine Learning ApplicationsYalçın Yenigün
 
Digital firm in the world with the best era
Digital firm in the world with the best eraDigital firm in the world with the best era
Digital firm in the world with the best erardeepan113
 
Barga Data Science lecture 2
Barga Data Science lecture 2Barga Data Science lecture 2
Barga Data Science lecture 2Roger Barga
 
Machine Learning SPPU Unit 1
Machine Learning SPPU Unit 1Machine Learning SPPU Unit 1
Machine Learning SPPU Unit 1Amruta Aphale
 
Recsys 2016 tutorial: Lessons learned from building real-life recommender sys...
Recsys 2016 tutorial: Lessons learned from building real-life recommender sys...Recsys 2016 tutorial: Lessons learned from building real-life recommender sys...
Recsys 2016 tutorial: Lessons learned from building real-life recommender sys...Xavier Amatriain
 
Machine learning --Introduction.pptx
Machine learning --Introduction.pptxMachine learning --Introduction.pptx
Machine learning --Introduction.pptxvinivijayan4
 

Similar to Introduction to Machine Learning (20)

ML.ppt
ML.pptML.ppt
ML.ppt
 
ML.ppt
ML.pptML.ppt
ML.ppt
 
ML.ppt
ML.pptML.ppt
ML.ppt
 
ML.ppt
ML.pptML.ppt
ML.ppt
 
ML.pptvdvdvdvdvdfvdfgvdsdgdsfgdfgdfgdfgdf
ML.pptvdvdvdvdvdfvdfgvdsdgdsfgdfgdfgdfgdfML.pptvdvdvdvdvdfvdfgvdsdgdsfgdfgdfgdfgdf
ML.pptvdvdvdvdvdfvdfgvdsdgdsfgdfgdfgdfgdf
 
ML.ppt
ML.pptML.ppt
ML.ppt
 
Rahul_Kirtoniya_11800121032_CSE_Machine_Learning.pptx
Rahul_Kirtoniya_11800121032_CSE_Machine_Learning.pptxRahul_Kirtoniya_11800121032_CSE_Machine_Learning.pptx
Rahul_Kirtoniya_11800121032_CSE_Machine_Learning.pptx
 
Machine Learning Contents.pptx
Machine Learning Contents.pptxMachine Learning Contents.pptx
Machine Learning Contents.pptx
 
Machine learning basics by akanksha bali
Machine learning basics by akanksha baliMachine learning basics by akanksha bali
Machine learning basics by akanksha bali
 
Machine learning basics
Machine learning basics Machine learning basics
Machine learning basics
 
ML_Module_1.pdf
ML_Module_1.pdfML_Module_1.pdf
ML_Module_1.pdf
 
Introduction to ML (Machine Learning)
Introduction to ML (Machine Learning)Introduction to ML (Machine Learning)
Introduction to ML (Machine Learning)
 
Machine Learning: Applications, Process and Techniques
Machine Learning: Applications, Process and TechniquesMachine Learning: Applications, Process and Techniques
Machine Learning: Applications, Process and Techniques
 
Building High Available and Scalable Machine Learning Applications
Building High Available and Scalable Machine Learning ApplicationsBuilding High Available and Scalable Machine Learning Applications
Building High Available and Scalable Machine Learning Applications
 
Digital firm in the world with the best era
Digital firm in the world with the best eraDigital firm in the world with the best era
Digital firm in the world with the best era
 
Barga Data Science lecture 2
Barga Data Science lecture 2Barga Data Science lecture 2
Barga Data Science lecture 2
 
Machine Learning SPPU Unit 1
Machine Learning SPPU Unit 1Machine Learning SPPU Unit 1
Machine Learning SPPU Unit 1
 
Machine learning
Machine learning Machine learning
Machine learning
 
Recsys 2016 tutorial: Lessons learned from building real-life recommender sys...
Recsys 2016 tutorial: Lessons learned from building real-life recommender sys...Recsys 2016 tutorial: Lessons learned from building real-life recommender sys...
Recsys 2016 tutorial: Lessons learned from building real-life recommender sys...
 
Machine learning --Introduction.pptx
Machine learning --Introduction.pptxMachine learning --Introduction.pptx
Machine learning --Introduction.pptx
 

Recently uploaded

DC MACHINE-Motoring and generation, Armature circuit equation
DC MACHINE-Motoring and generation, Armature circuit equationDC MACHINE-Motoring and generation, Armature circuit equation
DC MACHINE-Motoring and generation, Armature circuit equationBhangaleSonal
 
VIP Call Girls Palanpur 7001035870 Whatsapp Number, 24/07 Booking
VIP Call Girls Palanpur 7001035870 Whatsapp Number, 24/07 BookingVIP Call Girls Palanpur 7001035870 Whatsapp Number, 24/07 Booking
VIP Call Girls Palanpur 7001035870 Whatsapp Number, 24/07 Bookingdharasingh5698
 
2016EF22_0 solar project report rooftop projects
2016EF22_0 solar project report rooftop projects2016EF22_0 solar project report rooftop projects
2016EF22_0 solar project report rooftop projectssmsksolar
 
Thermal Engineering Unit - I & II . ppt
Thermal Engineering  Unit - I & II . pptThermal Engineering  Unit - I & II . ppt
Thermal Engineering Unit - I & II . pptDineshKumar4165
 
Block diagram reduction techniques in control systems.ppt
Block diagram reduction techniques in control systems.pptBlock diagram reduction techniques in control systems.ppt
Block diagram reduction techniques in control systems.pptNANDHAKUMARA10
 
Unit 2- Effective stress & Permeability.pdf
Unit 2- Effective stress & Permeability.pdfUnit 2- Effective stress & Permeability.pdf
Unit 2- Effective stress & Permeability.pdfRagavanV2
 
notes on Evolution Of Analytic Scalability.ppt
notes on Evolution Of Analytic Scalability.pptnotes on Evolution Of Analytic Scalability.ppt
notes on Evolution Of Analytic Scalability.pptMsecMca
 
Navigating Complexity: The Role of Trusted Partners and VIAS3D in Dassault Sy...
Navigating Complexity: The Role of Trusted Partners and VIAS3D in Dassault Sy...Navigating Complexity: The Role of Trusted Partners and VIAS3D in Dassault Sy...
Navigating Complexity: The Role of Trusted Partners and VIAS3D in Dassault Sy...Arindam Chakraborty, Ph.D., P.E. (CA, TX)
 
A Study of Urban Area Plan for Pabna Municipality
A Study of Urban Area Plan for Pabna MunicipalityA Study of Urban Area Plan for Pabna Municipality
A Study of Urban Area Plan for Pabna MunicipalityMorshed Ahmed Rahath
 
FULL ENJOY Call Girls In Mahipalpur Delhi Contact Us 8377877756
FULL ENJOY Call Girls In Mahipalpur Delhi Contact Us 8377877756FULL ENJOY Call Girls In Mahipalpur Delhi Contact Us 8377877756
FULL ENJOY Call Girls In Mahipalpur Delhi Contact Us 8377877756dollysharma2066
 
Thermal Engineering -unit - III & IV.ppt
Thermal Engineering -unit - III & IV.pptThermal Engineering -unit - III & IV.ppt
Thermal Engineering -unit - III & IV.pptDineshKumar4165
 
University management System project report..pdf
University management System project report..pdfUniversity management System project report..pdf
University management System project report..pdfKamal Acharya
 
Top Rated Call Girls In chittoor 📱 {7001035870} VIP Escorts chittoor
Top Rated Call Girls In chittoor 📱 {7001035870} VIP Escorts chittoorTop Rated Call Girls In chittoor 📱 {7001035870} VIP Escorts chittoor
Top Rated Call Girls In chittoor 📱 {7001035870} VIP Escorts chittoordharasingh5698
 
Hazard Identification (HAZID) vs. Hazard and Operability (HAZOP): A Comparati...
Hazard Identification (HAZID) vs. Hazard and Operability (HAZOP): A Comparati...Hazard Identification (HAZID) vs. Hazard and Operability (HAZOP): A Comparati...
Hazard Identification (HAZID) vs. Hazard and Operability (HAZOP): A Comparati...soginsider
 

Recently uploaded (20)

Call Girls in Ramesh Nagar Delhi 💯 Call Us 🔝9953056974 🔝 Escort Service
Call Girls in Ramesh Nagar Delhi 💯 Call Us 🔝9953056974 🔝 Escort ServiceCall Girls in Ramesh Nagar Delhi 💯 Call Us 🔝9953056974 🔝 Escort Service
Call Girls in Ramesh Nagar Delhi 💯 Call Us 🔝9953056974 🔝 Escort Service
 
Call Girls in Netaji Nagar, Delhi 💯 Call Us 🔝9953056974 🔝 Escort Service
Call Girls in Netaji Nagar, Delhi 💯 Call Us 🔝9953056974 🔝 Escort ServiceCall Girls in Netaji Nagar, Delhi 💯 Call Us 🔝9953056974 🔝 Escort Service
Call Girls in Netaji Nagar, Delhi 💯 Call Us 🔝9953056974 🔝 Escort Service
 
(INDIRA) Call Girl Bhosari Call Now 8617697112 Bhosari Escorts 24x7
(INDIRA) Call Girl Bhosari Call Now 8617697112 Bhosari Escorts 24x7(INDIRA) Call Girl Bhosari Call Now 8617697112 Bhosari Escorts 24x7
(INDIRA) Call Girl Bhosari Call Now 8617697112 Bhosari Escorts 24x7
 
DC MACHINE-Motoring and generation, Armature circuit equation
DC MACHINE-Motoring and generation, Armature circuit equationDC MACHINE-Motoring and generation, Armature circuit equation
DC MACHINE-Motoring and generation, Armature circuit equation
 
Cara Menggugurkan Sperma Yang Masuk Rahim Biyar Tidak Hamil
Cara Menggugurkan Sperma Yang Masuk Rahim Biyar Tidak HamilCara Menggugurkan Sperma Yang Masuk Rahim Biyar Tidak Hamil
Cara Menggugurkan Sperma Yang Masuk Rahim Biyar Tidak Hamil
 
VIP Call Girls Palanpur 7001035870 Whatsapp Number, 24/07 Booking
VIP Call Girls Palanpur 7001035870 Whatsapp Number, 24/07 BookingVIP Call Girls Palanpur 7001035870 Whatsapp Number, 24/07 Booking
VIP Call Girls Palanpur 7001035870 Whatsapp Number, 24/07 Booking
 
2016EF22_0 solar project report rooftop projects
2016EF22_0 solar project report rooftop projects2016EF22_0 solar project report rooftop projects
2016EF22_0 solar project report rooftop projects
 
Thermal Engineering Unit - I & II . ppt
Thermal Engineering  Unit - I & II . pptThermal Engineering  Unit - I & II . ppt
Thermal Engineering Unit - I & II . ppt
 
Block diagram reduction techniques in control systems.ppt
Block diagram reduction techniques in control systems.pptBlock diagram reduction techniques in control systems.ppt
Block diagram reduction techniques in control systems.ppt
 
Unit 2- Effective stress & Permeability.pdf
Unit 2- Effective stress & Permeability.pdfUnit 2- Effective stress & Permeability.pdf
Unit 2- Effective stress & Permeability.pdf
 
notes on Evolution Of Analytic Scalability.ppt
notes on Evolution Of Analytic Scalability.pptnotes on Evolution Of Analytic Scalability.ppt
notes on Evolution Of Analytic Scalability.ppt
 
Navigating Complexity: The Role of Trusted Partners and VIAS3D in Dassault Sy...
Navigating Complexity: The Role of Trusted Partners and VIAS3D in Dassault Sy...Navigating Complexity: The Role of Trusted Partners and VIAS3D in Dassault Sy...
Navigating Complexity: The Role of Trusted Partners and VIAS3D in Dassault Sy...
 
A Study of Urban Area Plan for Pabna Municipality
A Study of Urban Area Plan for Pabna MunicipalityA Study of Urban Area Plan for Pabna Municipality
A Study of Urban Area Plan for Pabna Municipality
 
Integrated Test Rig For HTFE-25 - Neometrix
Integrated Test Rig For HTFE-25 - NeometrixIntegrated Test Rig For HTFE-25 - Neometrix
Integrated Test Rig For HTFE-25 - Neometrix
 
FULL ENJOY Call Girls In Mahipalpur Delhi Contact Us 8377877756
FULL ENJOY Call Girls In Mahipalpur Delhi Contact Us 8377877756FULL ENJOY Call Girls In Mahipalpur Delhi Contact Us 8377877756
FULL ENJOY Call Girls In Mahipalpur Delhi Contact Us 8377877756
 
Thermal Engineering -unit - III & IV.ppt
Thermal Engineering -unit - III & IV.pptThermal Engineering -unit - III & IV.ppt
Thermal Engineering -unit - III & IV.ppt
 
University management System project report..pdf
University management System project report..pdfUniversity management System project report..pdf
University management System project report..pdf
 
(INDIRA) Call Girl Meerut Call Now 8617697112 Meerut Escorts 24x7
(INDIRA) Call Girl Meerut Call Now 8617697112 Meerut Escorts 24x7(INDIRA) Call Girl Meerut Call Now 8617697112 Meerut Escorts 24x7
(INDIRA) Call Girl Meerut Call Now 8617697112 Meerut Escorts 24x7
 
Top Rated Call Girls In chittoor 📱 {7001035870} VIP Escorts chittoor
Top Rated Call Girls In chittoor 📱 {7001035870} VIP Escorts chittoorTop Rated Call Girls In chittoor 📱 {7001035870} VIP Escorts chittoor
Top Rated Call Girls In chittoor 📱 {7001035870} VIP Escorts chittoor
 
Hazard Identification (HAZID) vs. Hazard and Operability (HAZOP): A Comparati...
Hazard Identification (HAZID) vs. Hazard and Operability (HAZOP): A Comparati...Hazard Identification (HAZID) vs. Hazard and Operability (HAZOP): A Comparati...
Hazard Identification (HAZID) vs. Hazard and Operability (HAZOP): A Comparati...
 

Introduction to Machine Learning

  • 1. Introduction to Machine Learning Sudeshna Sarkar IIT Kharagpur Module 1: Introduction Part A: Introduction
  • 2. Overview of Course 1. Introduction 2. Linear Regression and Decision Trees 3. Instance based learning Feature Selection 4. Probability and Bayes Learning 5. Support Vector Machines 6. Neural Network 7. Introduction to Computational Learning Theory 8. Clustering
  • 3. Module 1 1. Introduction a) Introduction b) Different types of learning c) Hypothesis space, Inductive Bias d) Evaluation, Training and test set, cross-validation 2. Linear Regression and Decision Trees 3. Instance based learning Feature Selection 4. Probability and Bayes Learning 5. Support Vector Machines 6. Neural Network 7. Introduction to Computational Learning Theory 8. Clustering
  • 4. Machine Learning History • 1950s: – Samuel's checker-playing program • 1960s: – Neural network: Rosenblatt's perceptron – Minsky & Papert prove limitations of Perceptron • 1970s: – Symbolic concept induction – Expert systems and knowledge acquisition bottleneck – Qui la ’s ID3 – Natural language processing (symbolic)
  • 5. Machine Learning History • 1980s: – Advanced decision tree and rule learning – Learning and planning and problem solving – Resurgence of neural network – Valia t’s PAC learning theory – Focus on experimental methodology • 90's ML and Statistics – Data Mining – Adaptive agents and web applications – Text learning – Reinforcement learning – Ensembles – Bayes Net learning • 1994: Self-driving car road test • 1997: Deep Blue beats Gary Kasparov
  • 6. Machine Learning History • Popularity of this field in recent time and the reasons behind that – New software/ algorithms • Neural networks • Deep learning – New hardware • GPU’s – Cloud Enabled – Availability of Big Data • 2009: Google builds self driving car • 2011: Watson wins Jeopardy • 2014: Human vision surpassed by ML systems
  • 7. Programs vs learning algorithms Algorithmic solution Machine learning solution Computer Data Program Output Computer Data Output Program
  • 8. Machine Learning : Definition • Learning is the ability to improve one's behaviour based on experience. • Build computer systems that automatically improve with experience • What are the fundamental laws that govern all learning processes? • Machine Learning explores algorithms that can – learn from data / build a model from data – use the model for prediction, decision making or solving some tasks
  • 9. Machine Learning : Definition • A computer program is said to learn from experience E with respect to some class of tasks T and performance measure P, if its performance at tasks in T, as measured by P, improves with experience E. [Mitchell]
  • 10. Components of a learning problem • Task: The behaviour or task being improved. – For example: classification, acting in an environment • Data: The experiences that are being used to improve performance in the task. • Measure of improvement : – For example: increasing accuracy in prediction, acquiring new, improved speed and efficiency
  • 13. Many domains and applications Medicine: • Diagnose a disease – Input: symptoms, lab measurements, test results, DNA tests, – Output: o e of set of possi le diseases, or o e of the a o e • Data: historical medical records • Learn: which future patients will respond best to which treatments
  • 14. Many domains and applications Vision: • say what objects appear in an image • convert hand-written digits to characters 0..9 • detect where objects appear in an image
  • 15. Many domains and applications Robot control: • Design autonomous mobile robots that learn from experience to – Play soccer – Navigate from their own experience
  • 16. Many domains and applications NLP: • detect where entities are mentioned in NL • detect what facts are expressed in NL • detect if a product/movie review is positive, negative, or neutral Speech recognition Machine translation
  • 17. Many domains and applications Financial: • predict if a stock will rise or fall • predict if a user will click on an ad or not
  • 18. Application in Business Intelligence • Forecasting product sales quantities taking seasonality and trend into account. • Identifying cross selling promotional opportunities for consumer goods. • …
  • 19. Some other applications • Fraud detection : Credit card Providers • determine whether or not someone will default on a home mortgage. • Understand consumer sentiment based off of unstructured text data. • Fore asti g o e ’s o i tio rates ased off external macroeconomic factors.
  • 21. Design a Learner Experiences Data Background knowledge/ Bias Problem/ Task Answer/ Performance Learn er Reaso ner Models 1. Choose the training experience 2. Choose the target function (that is to be learned) 3. Choose how to represent the target function 4. Choose a learning algorithm to infer the target function
  • 22. Choosing a Model Representation • The richer the representation, the more useful it is for subsequent problem solving. • The richer the representation, the more difficult it is to learn. • Components of Representation – Features – Function class / hypothesis language