AI: Week 1

Fall 2014

Tom Henderson

CS 5300

What is AI?

I is automated (in machine or

constructed artifact)

• From biological cells? (slime mold)

• By mimicking biology? (see Edelman)

• Are animals (other than humans)

intelligent?

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What is AI?

• Is AI abstract?

• i.e., collection of algorithms

• Or must be embodied?

• Is Eagle Eye or SkyNet an AI system?

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Eagle Eye as AI?

Book’s list of capabilities:

• NLP √

• Knowledge Rep √

• Automated Reasoning √

• Machine Learning √

• Computer Vision √

• Robotics √

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Can’t distinguish

system from human

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Some Issues

Thinking:

• Like Human (Cognitive Science)

• Rationally (Logic)

Acting:

• Like Human (Turing Test)

• Rationally (Best Expected Outcome)

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Some Other Issues

Intelligence:

• Abstract (Descartes)

• Physical (Skinner)

Computation:

• Discrete (Turing Machines)

• Continuous (Real Numbers)

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Abstract Smarts

• Language (e.g., English)

• Math (algebra, logic, geometry)

• Games (chess, cards, backgammon)

• Science (Physics)

• Problem Solving (word problems)

• Planning (moving, route optimization)

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Physical Smarts

• Sports (soccer)

• Dexterity (surgery, manipulation)

• Social skills (humanoid robots)

• Service (health, disability)

• Security (homes, business)

• Military

Is AI Math or Science?

• Math: axiomatic method

• Science:

• Observe Phenomenon

• Develop Model (math, process, concept)

• Predict Phenomena

• Validate predictions via experiment

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Math

• Development of abstractions that

idealize aspects of the world

• E.g., “straight line”

• Axiomatic method

• Assume axioms true

• Choose inference procedures

• Theory is what follows

• Validity: syntax or semantics

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Requires mapping to specific domain

Logic Example

1. Socrates is a man

2. All men are mortal

-----------------------------

? Conclusion

Socrates better think of something

fast if he doesn’t want to die!

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Scientific Method

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Phenomenon ObservationsExperiments

Model Predictions

Computer

Simulation

Verification

Hypothesis Validation

Simulations

Scientific Method

Theory must be falsifiable

I.e., there exist experiments to

distinguish from other theories

E.g., “Intelligence arises from an

undetectable force from a parallel

universe”

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Outlook

• Why optimistic?

Living creatures offer proof of

existence

• Why pessimistic?

Success does not come easily!

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Misleading Jargon

“agent” program

“percept” sensor data

“knowledge” data/structures

“learning” modify data structures

“artificial life” e.g., Brooks is working

on primordial soup

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Mapping as a Paradigm

• Discrete: if – then –

• Continuous: dx/dt = f(x,…) + del x

Allows for moving around in a space

Can roll downhill to solution

Have attractors and repellors

Need to know some math (chemistry?)

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Environment Modeling

• If performance is important (!!), then

need model of environment and an

evaluation function

Why not simulate to determine best

action?

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Environment Modeling

• If performance in real world is

important, how can we hope

abstraction will succeed (we leave

out too much)?

Use real world to train/learn etc.

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Foundations

• Philosophy

• Mathematics

• Engineering

• Psychology

• Economics

• Neuroscience

• Linguistics

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Foundations

AI, taking humans as the primary

object of study, involves the

attempt to understand all

aspects of what is means to be

human.

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Why Study AI?

• Cultural imperative:

“So God created man in his own

image”

• Androids to take menial tasks

• Mental prosthetic

• …

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Fundamental Issues

• Knowledge

• Inference

• Goals

• Language

Do these exist? Or are they

linguistic structures?

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Is AI Possible?

Weak AI Hypothesis: Machines can act

intelligently

Strong AI Hypothesis: Machines can be

intelligent

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Physical Symbol Hypothesis

• Computational processes operate on

symbol structures

• Cognition is symbol manipulation

(Proposed by Newell and Simon)

PSH: A necessary and sufficient condition

for general intelligent action is the ability

to manipulate symbol structures

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View from the Other Side

Are humans just machines (e.g., meat

machines as Marvin Minsky says)?

Will reductionism work? I.e., figure out

the physics and chemistry in a

bottom-up approach.

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Meaning???

• Functionalism: “a mental state is any

intermediate causal condition

between input and output … any two

systems with isomorphic causal

processes would have the same

mental state.” (p. 954)

Can this ever occur?

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The Chinese Room

This teaser gets at the heart of the matter:

A program is running, and the computer (human or

machine) does not really understand anything that

happens or why.

Is this the way a human body functions?

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Searle’s Axioms

1. Computer programs are formal, syntactic

entities.

2. Minds have mental contents, or semantics.

3. Syntax by itself is not sufficient for semantics.

4. Brains cause minds.

Thus, programs are not sufficient for mind.

(Can you prove this using propositional logic?)

Do you accept axiom 3?

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Major AI Contexts (1)

“Mind can be modeled through the adequate

combination of interacting functional machines

(modules)… the mind is a multitude of

interacting components … and a hack … only a

model incorporating a rich spectrum of (animal

or human) mental functioning will give us a

correct picture of the broad principles underlying

intelligence.” from: “Contructionist Design

Methodology for Interactive Intelligences,” AI

Magazine, Winter 2004, Vol. 25, No 4, pp.77-90

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Major AI Contexts (2)

“A biologically oriented definition of intelligence is the

starting point of the investigation. Intelligence is

defined with respect to the capability of an

autonomous system to maintain itself. This gives an

objective criterion, as opposed to subjective criteria

based on judgment of performance or the ascription

of knowledge or reasoning. This definition is refined

by considering functionalities used to increase the

chances of survival: representation, specialization,

cooperation, communication, reflection, etc.

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Major AI Contexts (2 cont’d)

“A theory of intelligence must be compatible with the basic laws of

physics and biology and it must be a universal theory, I.e.,

independent of a particular embodiment (wetware or silicon) or

system level (brain component, individual agent, society). This

universality can be achieved by using complex dynamical

systems theory as a foundation. Intelligence then is seen as

the result of a set of nonlinear processes which exhibit

properties also found in other physical systems. Phenomena

like behavioral coherence, cooperation, or the emergence of

diversity between agents can be explained using bifurcation

theory, chaos, self-organization, etc.” from: “Intelligence –

Dynamics and Representation,” Luc Steels, in The Biology and

Technology of Intelligent Autonomous Agents, Springer, 1995.

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Patterns from Dynamical Systems

E.g., Stripe Pattern

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Bio-systems Observations

• Pattern Formation in Nature

• Role of Developmental Cycle

• Environmental Niche

• Context, Signals and Algorithms

• Dissipative Information Systems

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Patterns and Coloration

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Role of Development

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Evolutionary Niche

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Similarity of Patterns

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Context and Signals

Turing’s Morphogenesis Idea

• “The Chemical Basis of Morphogenesis”

• http://www.dna.caltech.edu/courses/cs191/

paperscs191/turing.pdf

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Reaction-Diffusion Patterns

Formula:

cDcft

c 2)(

reactiondiffusion

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Example: Turing’s Morphogenesis Approach

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Example: Turing’s Morphogenesis Approach

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Caricature of Alan Turing

Playing hockey

(by his mom)

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Major AI Contexts (3)

Gerald Edelman: An adequate theory of

consciousness must contain an explanation of the

properties of conscious experience. It should account

both for intentionality and for the discriminability of qualia

or phenomenal experiences. To qualify as a scientific

account, a theoretical analysis od consciousness must

achieve four goals: (1) propose explicit neural models

that explain how consciousness can arise; (2) relate

these models to the emergence of consciousness during

evolution and development; (3) relate these models to

concept formation, memory, and language; and (4)

describe stringent tests for the models in terms of known

neurobiological facts.

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Questions?

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What is an Agent Function?

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Agent Function

• Abstract

• External View

• Complete Map

f: {P}* A

perceptaction

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What is a Percept?

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Percept

A vector:

Must a percept vector be finite?

nPPPP ...21

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Percepts

• Enumerable single percepts

• Enumerable sequences

• Experimentally find where percept

sequence goes

aPs

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How To Organize Ps Selection?

• One Percept?

E.g., [<room>,<dirt status>]

[A,Clean], [A,Dirty],[B,Clean],[B,Dirty]

#rooms * #status_states

What if there’re an infinite #???

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Two Percepts

Number possibilities is |S1|*|S2|

Are all perception sequences possible?

Can we arrange to try them all?

If so, why?

Build Behavior Model (Agent Function)

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What is an Agent Program?

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Agent Program

• Concrete

• Internal

• Implementation

• Just Current Percept

• Maybe persistent state

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How Should We Design an

Agent Function?

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Do the right thing

Do the most successful thing

Need measures of success

(performance measures)

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What is a Rational Agent?

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Rational Agent

For every perception sequence

Select an action that is

Expected to maximize a

Performance measure

Given evidence of P*

and knowledge

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Example

Given an agent that always vacuums,

and the performance criterion p. 38

and one more: -1 for vacuuming,

Show it is not a rational agent.

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Agents

Agent

sensors (percepts)

Environment

actions

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Current Approach

Programmer does most of work!

• Skeleton agent

• Table-driven agent

• Simple reflex agent

• Reflex agent with state

• Utility agent

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Autonomy

What is it?

• Freedom to choose action?

• Behavior based on experience?

• Behavior not programmed in?

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Autonomy

Book argues:

• Compensate for partial or incorrect knowledge

• With experience, becomes effectively independent of prior knowledge

Do you buy that?

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Autonomy

Last assertion too strong:

Choose appropriate action based on

context.

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Agent Structure

Map percepts (and state!) to actions

Percepts: Bump, Dirt, Home

Actions: Forward, Right, Left, Suck,

Stop

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Agent Functions and Programs

An agent is completely specified by the

agent function mapping percepts to

actions

One agent function is rational

Aim: Find a way to implement concisely

An agent program takes a single

percept as input, keeps internal state

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Enumeration vs. ???

Is there an approach to capture the

infinite percept and behavior issue?

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Consider

What is it?

Geometrically?

Numerically?

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Skeleton Agent

function SKELETON-AGENT(percept) returns action

static: memory, the agent’s memory of the world

memory Update-Memory(memory,percept)

action Choose-Best-Action(memory)

memory Update-Memory(memory,action)

return action

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Agent Types

Four basic types in order of increasing

generality:

• Simple reflex agents

• Reflex agents with state

• Goal-based agents

• Utility-based agents

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The Vacuum World

Percepts: [bump,dirt,home]

Actions: STOP, FORWARD, SUCK,

LEFT, RIGHT

Goals: (performance measure)

• +100 for each pile of dirt cleaned up

• -1 for each action

• -1000 for stopping not at home

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The Vacuum World

Environment:

• Grid, walls/obstacles, dirt, agent body

• Movement actions work unless bump

into wall

• Suck action cleans dirt from cell

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Some Issues

• hidden goals in reflex agent; determine from:

Behavior? Observables?

• learned vs. prior knowledge

• Nature/nurture, learned/innate

• agent = architecture+program: does this cover

everything? How about people? Adaptation?

• model how world evolves and how actions affect

world: simulation?

Assignment 1

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[pm,pc,nm,rt] = CS6380_Assgn1_run_sim(10,0.4,200,10,10);

>> pm

pm = 121

>> pc

pc = 1

>> nm

nm = 1170

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function trace = CS5300_random_walk(row0,col0,max_time,num_rows,num_cols)

%

trace = [row0,col0];

del_row = [0,-1,-1,-1,0,1,1,1];

del_col = [1,1,0,-1,-1,-1,0,1];

row = row0;

col = col0;

t = 0;

while t<max_time

t = t + 1;

perm = randperm(8);

dir = perm(1);

new_row = row + del_row(dir);

new_col = col + del_col(dir);

if new_row>0&&new_row<=num_rows&&new_col>0&&new_col<=num_cols

row = new_row;

col = new_col;

end

trace = [trace; row,col];

end

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From: Simulation,

Modeling and Analysis

A.M. Law

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From: Simulation,

Modeling and Analysis

A.M. Law

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From: Simulation,

Modeling and Analysis

A.M. Law

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From: Simulation,

Modeling and Analysis

A.M. Law

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From: Simulation,

Modeling and Analysis

A.M. Law

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Questions?