CS 416 Artificial Intelligence

1
CS 416Artificial Intelligence

• Lecture 2
• Introduction

2
CS at UVa

• 11M in research grants each year
• Top 5 of research is funded by NSF
• Faculty trips to NSF set national funding
  priorities
• Free MSFT Visual Studio for all students
• 75 faculty growth in past six years
• Undergrad research awards from CRA
• Highest starting salary (in SEAS) for ugrads

3
Textbook

• This is a great book
• 2nd edition released three years ago
• Most widely used in U.S. universities
• Its so good.
• Im going to make you read it!
• Homework
• Read chapters 1 and 2

4
Survey Results

• Languages
• Supermajority prefers C
• Three people indicated theyll need C help
• LISP?
• Math
• Many w/o stat
• 7 w/o diffyq
• 14 w/o linear algebra

5

• 5 people w/o GUI experience
• 4 people w/o MSFT Windows
• 14 people dont play so many video games
• Where have you done the most programming?
• 216 17
• Graphics 15
• 201/202 6
• OS 2

6

• AI apps
• Chess, google, spam filter, finance, chatterbot,
  games, vacuum
• 12 of CPU for AI tasks in games?
• More about magic tricks than AI?

iRoomba - Rodney Brooks (MIT) company
7
Languages

• Is AI special in its PL needs?
• AI research used to be more symbolic
• A language had to make it easy to create symbols
  and to manipulate them
• Some symbols would operate on other symbols
• LISP supported programs as data and dynamic
  typing
• Modern AI is more quantitative
• No language has emerged with an advantage
• Our language choice cannot distract from learning
  AI

8
Languages

• C - Common industry language
• C gets a little closer to real-time OS
• Perl the duct tape of the Internet makes the
  easy things easy and the hard things impossible
  theres more than one way to do it
• Python theres only one way to do it
• Scheme easy to learn but difficult to extend
• Common Lisp the programmable programming
  language nontrivial to learn but a decidedly
  different experience from programming in
  imperative languages

9
What is expected of you

• Youll have to do math
• Neural network update function
• Multidimensional function minimization
• Probability Bayes Rule
• We will teach necessary parts ofstatistics and
  linear algebra

Calculus expected.Probability and Linear
Algebra beneficial.
10
What is expected of you

• You have to program
• The programming assignments are non-trivial
• C
• Requires integration with existing code libraries
• Input/output handling (images, for example)
• We do not teach programming in this course

CS 216 expected.Additional programmingexperience
beneficial.
11
AI Systems

• Thermostat
• Tic-Tac-Toe
• Your car
• Chess
• Google
• Babblefish

12
Examples

• Chess Deep Junior (IBM) tied Kasparov in 2003
  match

ATRs DB Android
Ritsumeikan University
Hondas Asimo
RHex Hexapod
13
AI Techniques

• Rule-based
• Fuzzy Logic
• Neural Networks
• Genetic Algorithms
• Exhaustive search
• Expert Systems
• Logic

14
How to Categorize These Systems

• Systems that think like humans
• Systems that act like humans
• Systems that think rationally
• Systems that act rationally

15
Systems that think/act like humans

• Its hard to study things you cant observe
• How can I know how you think?
• Observation is difficult (changing with fMRI).
  For the most part, you are a black box
• Cognitive Science
• How can I know how you act?
• Observation is possible, but hard to control all
  aspects of experimental conditions.
• Turing Test

16
Alan Turing Building a Brain

• World War II motivated computer advances
• Code breaking (1943, Colossus) Used to decipher
  telegrams encrypted using Germanys encryption
  machine
• Electronic Numerical Integrator and Computer
  (ENIAC, 1946)
• Turing greatly involved with British efforts to
  build computers and crack codes (Bletchley Park)
• Arrested for being a homosexual in 1952 and
  denied security clearance
• Committed suicide in 1954

17
Systems that think/act rationally

• Rely on logic itself rather than human to measure
  correctness
• Thinking rationally (logically)
• Socrates is a human All humans are mortal
  Socrates is mortal
• Logic formulas for synthesizing outcomes
• Acting rationally (logically)
• Even if method is illogical, the observed
  behavior must be rational

18
Perspective of this Course

• We will investigate the general principles of
  rational agents
• Not restricted to human actions and human
  environments
• Not restricted to human thought
• Not confined to only using laws of logic
• Anything goes so long as it produces rational
  behavior

19
What is AI?

• The use of computers to solve problems that
  previously could only be solved by applying human
  intelligence. thus something can fit this
  definition today, but, once we see how the
  program works and understand the problem, we will
  not think of it as AI anymore (David Parnas)

20
Foundations - Philosophy

• Aristotle (384 B.C.E.) Author of logical
  syllogisms
• da Vinci (1452) designed, but didnt build,
  first mechanical calculator
• Descartes (1596) can human free will be
  captured by a machine? Is animal behavior more
  mechanistic?
• Necessary connection between logic and action is
  discovered

21
Foundations - Mathematics

• Leveraging uncertainty (Cardano 1501)
• Boolean logic (Boole, 1847)
• Analysis of limits to what can be computed
• Intractability (1965) time required to solve
  problem scales exponentially with the size of
  problem instance
• NP-complete (1971) Formal classification of
  problems as intractable

22
Foundations - Economics

• Game Theory study of rational behavior in small
  games
• Operations Research study of rational behavior
  in complex systems
• Herbert Simon (1916 2001) AI researcher who
  received Nobel Prize in Economics for showing
  people accomplish satisficing solutions, those
  that are good enough

23
Foundations - Neuroscience

• How do brains work?
• Early studies (1824) relied on injured and
  abnormal people to understand what parts of brain
  do
• More recent studies use accurate sensors to
  correlate brain activity to human thought
• By monitoring individual neurons, monkeys can now
  control a computer mouse using thought alone
• Melody Moore at GaState locked-in syndrome
• (Gordon) Moores law states computers will have
  as many gates as humans have neurons in 2020
• How close are we to having a mechanical brain?
• Parallel computation, remapping,
  interconnections, binary vs. gradient

24
Foundations - Psychology

• Helmholtz and Wundt (1821) started to make
  psychology a science by carefully controlling
  experiments
• The brain processes information (1842)
• Sense ? Think ? Act
• Cognitive science started at a MIT workshop in
  1956 with the publication of three very
  influential papers

25
Foundations Control Theory

• Machines can modify their behavior in response to
  the environment (sense / action loop)
• Water-flow regulator (250 B.C.E), steam engine
  governor, thermostat
• The theory of stable feedback systems (1894)
• Build systems that transition from initialstate
  to goal state with minimum energy
• In 1950, control theory could only
  describelinear systems and AI largely rose as
  aresponse to this shortcoming

26
Foundations - Linguistics

• Speech demonstrates so much of human intelligence
• Analysis of human language reveals thought taking
  place in ways not understood in other settings
• Children can create sentences they have never
  heard before
• Language and thought are believed to be tightly
  intertwined