Computer Science CPSC 422 Intelligent Systems Cristina Conati

Computer Science CPSC 422

Intelligent Systems

Cristina Conati

Super Brief Intro

• Advanced AI course• Builds upon 322 (and 312)

• 322 gave a broad, high level overview of main research areas in AI (logic, search, planning, reasoning under uncertainty, decision making)

• We will go into more depth on some of the topics • Look at “Learning”• Study some applications, in the field of Intelligent User Interfaces

Overview

• Administrivia

• Let’s connect back to 322: what is AI?

• Refresher

• Examples

PeopleInstructor• Cristina Conati ( conati@cs.ubc.ca;  office CICSR 125)

Teaching Assistant• Hajir Roozbehani (hajir@cs.ubc.ca)

Course Pages• Course website:

http://www.cs.ubc.ca/~conati/422/422-2010World/422-2010.html

• This site also includes a calendar with a tentative scheduling of topics.

http://www.cs.ubc.ca/~conati/422/422-2010World/schedule-422-2010.html

CHECK IT OFTEN! Lecture slides Assignments/SolutionsOther material

Course Material

• Main Textbook• Artificial Intelligence: A Modern Approach (AIMA). 3rd edition, Russell

and Norvig• Can buy cheaper e-version (http://www.coursesmart.com/9780136067337)

• Additional textbook: Artificial Intelligence: Foundations of Computational Agents. by Poole and Mackworth. (P&M)• I’ll post the relevant chapters in WebCT as needed• This textbook it is not a substitute for the AIMA textbook

Course Material

• Lecture Slides• I'll  post a version of each lecture's slides just after class.  • But I won't post  material that I write on the slides or on the board during

class. You'll have to come to class to get that .

• You are responsible for all the material in the readings for each class, regardless of whether it has been explicitly covered in class.

• You will also need to know all the material covered in class, whether or not it is included in the readings or available on-line.  

Readings

• It is strongly recommended that you read the assigned readings before each class. It will help you understand the material better when I lecture

• However, there will be some classes that are centered around the discussion of one or more research papers.• You MUST read the papers before coming to class, because • you will have to come up with questions on them and participate to class

discussion (more on this later)

How to Get Help?

• Use the WebCT Discussion Board for questions on course

material (so check it frequently)

• That way others can learn from your questions and comments

• Use email for personal questions (e.g., grade inquiries or health

problems).

• Go to office hours (Discussion Board is NOT a good substitute

for this) – times below are still tentative, will be finalized next week

• Cristina: likely Tu: 3:30-4:30

• Hajir: TBA

• Can schedule by appointment if you have a class conflict with the

official office hours

Evaluation

• Final exam (45%)• midterm exams (30%) • Assignments (15 %)• Class participation and questions for classes based on paper

discussion (10%)

But, if your final grade is 20% higher than your midterm grade:• Midterm: 15%• Final: 60 %

To pass: at least 50% in both your overall grade and your final

exam grade

Coursework: Assignments

• Submit via Handin by the appointed deadline.

• See syllabus for late assignment policy

• You will have one Late Assignment Bonus, i.e. you will be allowed to submit one of the assignments up to 2 days late with no penalty (see details in syllabus).

Is collaboration on assignments allowed? Yes, you may work with one (and only one) other person. • That person must also be a student in CPSC 422 this term.

• You will have to officially declare that you have collaborated with this person when submitting your assignment.

• There will be more details about collaboration policy included in the assignment itself.

Talking about the assignments with anybody other than an official teammate, looking at existing solutions, submitting solutions not worked out by the team members constitute plagiarism

See UBC official regulations on what constitutes plagiarism (pointer in syllabus)

Coursework: assignments

Coursework: discussion-based classes

• Discussion-based classes• There will be a few classes during the course that will be

centered on reading and discussing one or more research papers

• You will have to come up with critical questions (discussion points) on each of the

assigned readings (I will give you the exact number for each set of readings)

Hand in your questions (I’ll give you details on when and how to do this as we go)

Be prepared to present and discuss your questions in class

Coursework: discussion-based classes

• First discussion-based class: Tuesday, Jan. 19• Paper (available on-line from class schedule):

• Conati C., Gertner A., VanLehn K., 2002. Using Bayesian Networks to Manage Uncertainty in Student Modeling. User Modeling and User-Adapted Interaction. 12(4) p. 371-417.

• Make sure to have at least two questions on this  reading to  discuss  in class. 

• Send you questions to *both* conati@cs.ubc.ca and hajir@cs.ubc.ca by 9am on Tuesday, Jan. 19

• Hand in a written copy of the questions at the end of class

Questions on papers

• Clarification questions are welcome, but  there should be  at least two that can be used as “discussion points”, i.e. that• Question elements of the presented research (i.e. point out

weaknesses)• make connections with the relevant techniques presented in

class (Bnets in case of the first discussion paper)• Make connections/comparisons with other papers (once we

have covered enough papers to do this)

• Examples of questions of different quality are available from the syllabus

Missing Assignments or Exams

• If serious circumstances (like an illness or other personal matters) cause you to be late for an assignment or to miss an exam:• If you miss an assignment, your score will be reweighed to exclude that

assignment• If you miss the midterm, its weight will be shifted to the final

thus, your total grade will be 75 % final, 25% coursework• If you miss the final, you'll have to write a make-up final as soon as

possible

• If you have flu-like symptoms, you do not need to bring a doctor’s note, but you do need to report your illness at http://www.students.ubc.ca/health/flu.cfm

• For all other circumstamces, you do need official certification (e.g. doctor’s note)

To Summarize

• All the course logistics are described in the course syllabus• http://www.cs.ubc.ca/~conati/422/422-2010World/422-2010.html

• Make sure to read it and that you agree with the course rules before deciding to take the course

Department of Computer ScienceUndergraduate Events This Week

How to Prepare for the Tech Career Fair

Date: Wed. Jan 6

Time: 5 – 6:30 pm

Location: DMP 110

Resume Writing Workshop (for non-coop students)

Date: Thurs. Jan 7

Time: 12:30 – 2 pm

Location: DMP 201

CSSS Movie Night

Date: Thurs. Jan 7

Time: 6 – 10 pm

Location: DMP 310

Movies:

“Up” & “The Hangover”

(Free Popcorn & Pop)

Drop-In Resume Edition Session

Date: Mon. Jan 11

Time: 11 am – 2 pm

Location: Rm 255, ICICS/CS Bldg

Industry Panel

Speakers: Managers from Google, IBM, Microsoft, TELUS, etc.

Date: Tues. Jan 12

Time: Panel: 5:15 – 6:15 pm;

Networking: 6:15 – 7:15 pm

Location: Panel: DMP 110;

Networking: X-wing Undergrad

Lounge

Tech Career Fair

Date: Wed. Jan 13

Time: 10 am – 4 pm

Location: SUB Ballroom

Overview

• Administrivia

• Let’s connect back to 322: what is AI?

• Refresher

• Examples

What is Artificial Intelligence?

Systems that act like humans Systems that think rationally“The study of how to make computers do things at which, at the moment, people are better”(Rich and Knight, 1991)

“The study of mental faculties through the use of computational models” (Charniack and McDermott, 1985).

Systems that think like humans Systems that act rationally

“The automation of activities that we associate with human thinking, such as decision making, problem solving, learning”(Bellman, 1978)

“AI..is concerned with intelligent behavior in artifacts (Nilsson, 1998)

From: Russell S. and Norvig, P.``Artificial Intelligence: A Modern Approach.''

Systems that act like humans

• Turing test (1950): Can a human interrogator tell whether (written) responses to her (written) questions come from a human or a machine?• Natural Language Processing• Knowledge Representation• Automated Reasoning• Machine Learning

• Total Turing Test (extended to include physical aspects of human behavior)• Computer Vision• Robotic

Has any AI System Passed the Tutoring Test?

• Not the full blown one (see

http://www.loebner.net/Prizef/loebner-prize.html)• Loebner Prize initiative has a 100,000 and a Gold Medal for the first

computer whose responses were indistinguishable from a human's. No one has won this yet

• Each year a monetary prize and a bronze medal are awarded to the most

human-like computer.

• The winner is the best entry relative to other entries that year, irrespective of

how good it is in an absolute sense

• Variations restricted to specific tasks requiring some form of

intelligence

• Check Winner 2009 (http://www.worldsbestchatbot.com/Do_Much_More)

• And you can play with winner from 2008 (Elbot )

But why do we want an intelligent system to act like a human?

• Because for many tasks, humans are still the Gold Standard

But why do we want an intelligent system to act like a human?

Generating Multimedia Presentations Zhou, Wen, and Aggarwal. A Graph-Matching Approach to Dynamic Media Allocation

in Intelligent Multimedia Interfaces. Best Paper Award at Intelligent User Interfaces 2005.

• Algorithm to effectively allocate text and graphics in

multimedia presentations

• Empirical Validation• System (RIA) output on 50 user queries (real estate and tourist guide

application)

• Media allocation on same queries by two multimedia UI designers

• Third expert “blindly” ranked all responses

• Results• RIA best/co-best in 17 cases

• Minor differences in 28 of the remaining 33 cases

Why Replicate Human Behavior, Including its “Limitations”?

• AI and Entertainment

• E.g. Façade, a one-act interactive drama http://www.quvu.net/interactivestory.net/#publications

• Sometime these limitations can be useful, e.g.

• Supporting Human Learning via Peer interaction (Goodman, B., Soller, A., Linton, F., and Gaimari, R. (1997)

Encouraging Student Reflection and Articulation using a Learning Companion. Proceedings of

the AI-ED 97 World Conference on Artificial Intelligence in Education, Kobe, Japan, 151-158.)

• Supporting Human Learning via teachable agents

(Leelawong, K., & Biswas, G.

Designing Learning by Teaching Agents: The Betty's Brain System, International Journal of

Artificial Intelligence in Education, vol. 18, no. 3, pp. 181-208, 2008

What is Artificial Intelligence?

Systems that act like humans Systems that think rationally“The study of how to make computers do things at which, at the moment, people are better”(Rich and Knight, 1991)

“The study of mental faculties through the use of computational models” (Charniack and McDermott, 1985).

Systems that think like humans Systems that act rationally

“The automation of activities that we associate with human thinking, such as decision making, problem solving, learning”(Bellman, 1978)

“The branch of computer science that is concerned with the automation of intelligent behavior (Luger and Stubblefield 1993)

Systems That Think Like Humans• Use Computational Models to Understand the Actual

Workings of Human Mind• Devise/Choose a sufficiently precise theory of the mind• Express it as a computer program• Check match between program and human behavior (actions

and timing) on similar tasks

• Tight connections with Cognitive Science

• Also known as descriptive approaches to AI

Some Examples

• Newell and Simon’s GPS (General Problem Solver, 1961) to test means-end approach as general problem solving strategy

• John Anderson’s ACT-R cognitive architecture (http://act-r.psy.cmu.edu/)

• Anderson, J. R. & Lebiere, C. (1998). The atomic components of thought. Erlbaum; • Anderson, J. R., Bothell, D., Byrne, M. D., Douglass, S., Lebiere, C., & Qin, Y . (2004). An

integrated theory of the mind. Psychological Review 111, (4). 1036-1060.

• SOAR cognitive architecture (http://sitemaker.umich.edu/soar)

• Newell, A. 1990. Unified Theories of Cognition. Cambridge, Massachusetts: Harvard University Press.

ACT-R Models for Intelligent Tutoring Systems

Intelligent agents that support human learning and training

By autonomously and intelligently adapting to learners’ specific needs, like good teachers do

ACT-R Models for Intelligent Tutoring Systems

Cognitive Science

Education

ILE

Computer Science(AI, HCI)

Intelligent Tutoring Systems (ITS)

ACT-R Models for Intelligent Tutoring Systems• One of ACT-R main assumptions: Cognitive skills

(procedural knowledge) are represented as production rules:

IF this situation is TRUE, THEN do X

• An ACT-R model representing expertise in a given domain requires writing a set of production rules mimicking how a human would reason to perform tasks in that domain

• An ACT-R model for an ITS encodes all the reasoning steps necessary to solve problems in the target domain• Example: rules describing how to solve

5x+3=30

ACT-R Models for Intelligent Tutoring Systems

Eq: 5x+3=30 ; Goals: [Solve for x]• Rule: To solve for x when there is only one occurrence, unwrap (isolate) x.

Eq:5x+3=30 ; Goals: [Unwrap x]• Rule: To unwrap ?V, find the outermost wrapper ?W of ?V and remove ?W

Eq: 5x+3=30; Goals: [Find wrapper ?W of x; Remove ?W]• Rule: To find wrapper ?W of ?V, find the top level expression ?E on side of

equation containing ?V, and set ?W to part of ?E that does not contain ?V

Eq: 5x+3=30; Goals: [Remove “+3”]• Rule: To remove “+?E”, subtract “+?E” from both sides

Eq: 5x+3=30; Goals: [Subtract “+3” from both sides]• Rule: To subtract “+?E” from both sides ….

Eq: 5x+3-3=30-3

Model Tracing

• Given a rule-based representation of a target domain (e.g. algebra),

• an “expert model” can trace student performance by firing rules and do a stepwise comparison of rule outcome with student action

• Mismatches signal incorrect student knowledge that requires tutoring

• Knowledge tracing extends model tracing to assess probability that a student knows domain rules given observed actions

• These models showed good fit with student performance, indicating value of the ACT-R theory

• Also, the Cognitive Tutors based on this model are great examples of AI success – used in thousands of high schools in the USA (http://www.carnegielearning.com/success.cfm)

What is Artificial Intelligence?

Systems that act like humans Systems that think rationally“The study of how to make computers do things at which, at the moment, people are better”(Rich and Knight, 1991)

“The study of mental faculties through the use of computational models” (Charniack and McDermott, 1985).

Systems that think like humans Systems that act rationally

“The automation of activities that we associate with human thinking, such as decision making, problem solving, learning”(Bellman, 1978)

“The branch of computer science that is concerned with the automation of intelligent behavior (Luger and Stubblefield 1993)

Systems that Think Rationally

• Logic: formalize right thinking, i.e. irrefutable reasoning

processes.

• Logistic tradition in AI aims to build computational frameworks based on

logic.

• Then use these frameworks to build intelligent systems

• You have seen some examples in 322 (Propositional Logic) and

312 (Logic Programming)

• We will look at more advanced logic-based representations• Semantic Networks

• Ontologies

Systems that Think Rationally

• Main Research Problems/Challenges• Proving Soundness and Completeness of various formalisms

• How to represent often informal and uncertain domain

knowledge and formalize it in logic notation

• Computational Complexity

• Tradeoff between expressiveness and tractability in logic-

based systems H. J. Levesque and R. J. Brachman. Expressiveness and tractability in

knowledge representation and reasoning. Computational Intelligence, 3(2):78--93, 1987.

What is Artificial Intelligence?

Systems that act like humans Systems that think rationally“The study of how to make computers do things at which, at the moment, people are better”(Rich and Knight, 1991)

“The study of mental faculties through the use of computational models” (Charniack and McDermott, 1985).

Systems that think like humans Systems that act rationally

“The automation of activities that we associate with human thinking, such as decision making, problem solving, learning”(Bellman, 1978)

“The branch of computer science that is concerned with the automation of intelligent behavior (Luger and Stubblefield 1993)

Systems that Act Rationally

• The “think rationally” approach focuses on correct

inference

• But more is needed for rational behavior, e.g.• How to behave when there is no provably correct thing to do

(i.e. reasoning under uncertainty)

• Fully reactive behavior (instinct vs. reason)

AI as Study and Design of Intelligent Agents (Poole and Mackworth, 1999)

• An intelligent agent is such that• Its actions are appropriate for its goals and circumstances

• It is flexible to changing environments and goals

• It learns from experience

• It makes appropriate choices given perceptual limitations and limited

resources

• This definition drops the constraint of cognitive plausibility • Same as building flying machines by understanding general principles of

flying (aerodynamic) vs. by reproducing how birds fly

• Normative vs. Descriptive theories of Intelligent Behavior

Intelligent Agents

• In AI, artificial agents that have a physical presence in the world

are usually known as Robots

• Robotics is the field primarily concerned with the implementation

of the physical aspects of a robot (i.e. perception of the physical

environment, actions on the environment)

• Another class of artificial agents include interface agents, for

either stand alone or Web-based applications (e.g. intelligent

desktop assistants, recommender systems, intelligent tutoring

systems)

• Interface agents don’t have to worry about interaction with the

physical environment, but share all other fundamental

components of intelligent behavior with robots

• We will focus on these agents in this course

Intelligent Agents in the World

Natural Language Understanding

+ Computer Vision

Speech Recognition+

Physiological SensingMining of Interaction Logs

Knowledge RepresentationMachine Learning

Reasoning + Decision Theory

+ Robotics

+Human Computer

/RobotInteraction

Natural Language Generation

The “Act Rationally” viewThis is the view that was adopted in cpsc322, and that we will continue to explore in the first part of the course

• Reasoning under uncertainty: Bayesian networks and Hidden

Markov Models • Brief review, some applications, approximate inference

• Decision Making: planning under uncertainty• Markov Decision Processes, review

• Partially Observable Markov Decision Processes (POMDP)

• Learning• Decision Trees, Neural Networks, Learning Bayesian Networks,

Reinforcement Learning

Next Class

Review of Bayesian networks, and representational issues

IMPORTANT: You must be familiar with the basic concepts of probability theory. I won’t go over them.

For are refresher: Ch. 13 in textbook and review slides posted in the schedule page (Th. slot)