Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada,...

30
Computation: The Mathematical Story Christos H. Papadimitriou UC Berkeley christos

Transcript of Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada,...

Page 1: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

Com

puta

tion:

The

Mat

hem

atic

al S

tory

Chr

isto

s H. P

apad

imitr

iou

UC

Ber

kele

y�c

hris

tos�

Page 2: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

Out

line

�Th

e Fo

unda

tiona

l Cris

is in

Mat

h (1

900

�31

)�

How

it L

ed to

the

Com

pute

r (19

31 �

46)

�A

nd to

P v

sNP

(19

46 �

72)

Page 3: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

The

preh

isto

ry

of c

ompu

tatio

n

Pasc

al�s

Cal

cula

tor

1650

Bab

bage

& A

da, 1

850

the

anal

ytic

al e

ngin

e

Jacq

uard

�s lo

oms

1805

Page 4: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

Trou

ble

in M

ath

Non

-euc

lidea

nge

omet

ries

Can

tor,

1880

: se

ts a

nd in

finity∞

Page 5: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

The

ques

t for

foun

datio

ns

Hilb

ert,

1900

:�W

e m

ust k

now

,w

e ca

n kn

oww

e sh

all k

now

!�

Page 6: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

The

two

ques

ts

An

axio

mat

icsy

stem

that

com

pris

esal

l of M

athe

mat

ics

A m

achi

neth

at fi

nds

a pr

oof f

orev

ery

theo

rem

Page 7: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

The

disa

ster

Göd

el 1

931

The

Inco

mpl

eten

ess T

heor

em�s

omet

imes

, we

cann

ot k

now

�Th

eore

ms t

hat h

ave

no p

roof

Page 8: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

Rec

all t

he tw

o qu

ests

Find

an

axio

mat

icsy

stem

that

com

pris

esal

l of M

athe

mat

ics

?

Find

a m

achi

neth

at fi

nds a

proo

f for

ever

y th

eore

m

Page 9: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

Als

o im

poss

ible

?

but w

hat i

s a m

achi

ne?

Page 10: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

The

mat

hem

atic

al m

achi

nes (

1934

�37

)

Post

Kle

eneC

hurc

h

Turin

g

Page 11: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

Uni

vers

al T

urin

g m

achi

ne

Pow

erfu

l and

cru

cial

idea

whi

ch a

ntic

ipat

es so

ftwar

e

�an

d ra

dica

l too

:de

dica

ted

mac

hine

sw

ere

favo

red

at th

e tim

e

Page 12: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

�If i

t sho

uld

turn

out

that

the

basi

c lo

gics

of a

mac

hine

des

igne

d fo

r the

num

eric

also

lutio

n of

diff

eren

tial e

quat

ions

coi

ncid

ew

ith th

e lo

gics

of a

mac

hine

inte

nded

tom

ake

bills

for a

dep

artm

ent s

tore

, I w

ould

rega

rd th

is a

s the

mos

t am

azin

g co

inci

denc

eth

at I

have

eve

r enc

ount

ered

How

ard

Aik

en, 1

939

Page 13: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

In a

wor

ld w

ithou

t Tur

ing�

SPE

CIA

L T

OD

AY

: All

num

ber

crun

cher

s 40%

off

!

Bas

emen

t:G

ame

engi

nes,

Vid

eo a

nd M

usic

com

pute

rs

Thi

rd F

loor

:A

ccou

ntin

g co

mpu

ters

, Bus

ines

s mac

hine

s

Seco

nd F

loor

:D

atab

ase

engi

nes,

Wor

d pr

oces

sors

Firs

t Flo

or:

Web

bro

wse

rs, e

-mai

lers

WE

LC

OM

E T

O T

HE

CO

MPU

TE

R S

TO

RE

!

Page 14: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

And

fina

lly�

von

Neu

man

n 19

46ED

VA

C a

nd re

port

Page 15: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

John

ny c

ome

late

ly

�vo

n N

eum

ann

and

the

Inco

mpl

eten

ess T

heor

em�

�Tur

ing

has d

one

good

wor

k on

the

theo

ries

of a

lmos

t pe

riodi

c fu

nctio

ns a

nd o

f con

tinuo

us g

roup

s� (1

939)

�Zu

se(1

936

�44

) , T

urin

g (1

941

�52

), A

tana

soff

/Ber

ry

(193

7 �

42),

Aik

en (1

939

�45

), et

c.�

The

mee

ting

at th

e A

berd

een,

MD

trai

n st

atio

n�

The

�log

icia

ns�

vsth

e �e

ngin

eers

� at

UPe

nn�

Ecke

rt, M

auch

ly, G

olds

tine,

and

the

Fir

st D

raft

Page 16: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

Mad

ness

in th

eir m

etho

d?th

e pa

infu

l hum

an st

ory

G. C

anto

rD

. Hilb

ert

K. G

ödel

E. P

ost

A. M

. Tur

ing

J. V

on N

eum

ann

Page 17: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

Theo

ry o

f Com

puta

tion

sinc

e Tu

ring:

Effic

ient

alg

orith

ms

�So

me

prob

lem

s can

be

solv

ed in

pol

ynom

ial

time

(n, n

log

n, n

2 , n3 ,

etc.

)�

Oth

ers,

like

the

trave

ling

sale

sman

pro

blem

an

d B

oole

an sa

tisfia

bilit

y, a

ppar

ently

can

not

(bec

ause

they

invo

lve

expo

nent

ial s

earc

h)�

Impo

rtant

dic

hoto

my

(von

Neu

man

n 19

52,

Edm

onds

196

5, C

obha

m19

65, o

ther

s)

Page 18: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

Poly

nom

ial a

lgor

ithm

s del

iver

M

oore

�s L

aw to

the

wor

ld�

A 2

nal

gorit

hm fo

r SA

T, ru

n fo

r 1 h

our:

n=

53n

= 45

n=

38n

= 31

n=

23n

= 15

2006

1996

1986

1976

1966

1956

×2

×5

×10

0 ev

ery

deca

de

n7n3

An

nor

nlo

g n

algo

rithm

Page 19: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

NP-

com

plet

enes

sC

ook,

Kar

p, L

evin

(197

1 �

73)

�Ef

ficie

ntly

solv

able

pro

blem

s: P

�Ex

pone

ntia

l sea

rch:

NP

�M

any

com

mon

pro

blem

s cap

ture

the

full

pow

er

of e

xpon

entia

l sea

rch:

NP-

com

plet

e�

Arg

uabl

y th

e m

ost i

nflu

entia

l con

cept

to c

ome

out o

f Com

pute

r Sci

ence

�Is

P =

NP?

Fun

dam

enta

l que

stio

n an

d m

athe

mat

ical

pro

blem

Page 20: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

Inte

llect

ual d

ebt t

o G

ödel

/Tur

ing?

�N

egat

ive

resu

lts a

re a

n im

porta

nt

inte

llect

ual t

radi

tion

in C

ompu

ter S

cien

ce

and

Logi

c�

The

Inco

mpl

eten

ess T

heor

em a

nd T

urin

g�s

halti

ng p

robl

em a

re th

e ar

chet

ypic

al

nega

tive

resu

lts�

The

Göd

el le

tter (

disc

over

ed 1

992)

Page 21: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

Page 22: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

Page 23: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

Rec

all:

Hilb

ert�s

Que

st

axio

ms

+co

njec

ture

alw

ays a

nsw

ers

�yes

/no�

Turi

ng�s

hal

ting

prob

lem

Page 24: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

Göd

el�s

revi

sion

axio

ms

+co

njec

ture

ifth

ere

is a

pro

of

of le

ngth

nit

finds

it

in ti

me

k n

(this

is tr

ivia

l,ju

st tr

y al

l pro

ofs)

Page 25: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

Hilb

ert�s

last

stan

d

�G

ödel

ask

ed v

on N

eum

ann

in th

e 19

56

lette

r:�C

an th

is b

e do

ne in

tim

e n

?

n 2 ?

n c ?�

�Th

is w

ould

still

mec

hani

ze M

athe

mat

ics�

Page 26: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

Surp

rise!

�G

ödel

�s q

uest

ion

is e

quiv

alen

t to

�P =

NP�

�H

e se

ems t

o be

opt

imis

tic a

bout

it�

Page 27: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

So�

�H

ilber

t�s fo

unda

tions

que

st a

nd th

e In

com

plet

enes

s The

orem

hav

e st

arte

d an

in

telle

ctua

l Rub

e G

oldb

erg

that

eve

ntua

lly

led

to th

e co

mpu

ter

�So

me

of th

e m

ost i

mpo

rtant

con

cept

s in

toda

y�s C

ompu

ter S

cien

ce, i

nclu

ding

P vs

NP,

ow

e a

debt

to th

at tr

aditi

on

Page 28: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

And

this

is th

e st

ory

we

tell

in�

LOG

ICO

MIX

A g

raph

ic n

ovel

of r

easo

n, m

adne

ssan

d th

e bi

rth o

f the

com

pute

r

by�

Page 29: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

LOG

ICO

MIX

: A g

raph

ic n

ovel

of r

easo

n,

mad

ness

and

the

birt

h of

the

com

pute

rB

y A

post

olos

Dox

iadi

sand

Chr

isto

s Pap

adim

itrio

uA

rt: A

leco

sPap

adat

osan

d A

nnie

Di D

onna

Blo

omsb

ury,

200

7

Page 30: Computation: The Mathematical Story Christos H ... · Pascal™s Calculator 1650 Babbage & Ada, 1850 the analytical engine ... A machine that finds a proof for every theorem. The

HoC

, 12/

6/07

Than

k yo

u!