AArtificial rtificial IIntelligencentelligence

AIAI conference at Dartmouth conference at DartmouthCollege, 1956: McCarthy,College, 1956: McCarthy,Minsky, Newell, SimonMinsky, Newell, Simon

Newell, Shaw and Simon Newell, Shaw and Simon demonstrated demonstrated Logic TheoristLogic Theorist, a reasoning , a reasoning program written in IPL (Information program written in IPL (Information Processing Language)Processing Language)

IPL had support for linked lists, and IPL had support for linked lists, and caught McCarthy’s attentioncaught McCarthy’s attention

Dartmouth CollegeDartmouth College

Early Early AIAI Language Efforts Language Efforts

He wanted a language for He wanted a language for AIAI projects, but not projects, but not IPL: too low-level and IPL: too low-level and machine-specificmachine-specific

An IBM group (consulting An IBM group (consulting McCarthy) developedMcCarthy) developedFLPL: Fortran List Processing FLPL: Fortran List Processing LanguageLanguage

John McCarthy

McCarthy’s wish list, developed while writing McCarthy’s wish list, developed while writing AIAI programs (chess and differential calculus) programs (chess and differential calculus)

•Conditional expressionsConditional expressions

•RecursionRecursion

•Higher-order functions (like ML’s Higher-order functions (like ML’s mapmap))

•Garbage collectionGarbage collection

FLPL was not the answer for McCarthy’s group FLPL was not the answer for McCarthy’s group at MIT in 1958…at MIT in 1958…

A Lisp program is a list representing an AST: A Lisp program is a list representing an AST: (+ a (* b c))(+ a (* b c))

The plan was to use some Fortran-like The plan was to use some Fortran-like notationnotation

But McCarthy wrote a paper showing a simple But McCarthy wrote a paper showing a simple Lisp interpreter in Lisp: a function called Lisp interpreter in Lisp: a function called evaleval

To avoid syntax issues, he used the list-AST To avoid syntax issues, he used the list-AST form, both for form, both for evaleval’s input and for ’s input and for evaleval itself itself

This This evaleval, hand-translated into assembly , hand-translated into assembly language, became the first implementation of language, became the first implementation of LispLisp

Lisp’s Unusual SyntaxLisp’s Unusual Syntax

The group never gave up the idea of The group never gave up the idea of compiling from some Fortran-like syntaxcompiling from some Fortran-like syntax

But they never did it eitherBut they never did it either

Later, people tried to compile Lisp from a Later, people tried to compile Lisp from a Fortran- or Algol-like syntaxFortran- or Algol-like syntax

None of these efforts were very popularNone of these efforts were very popular

There are advantages to programs and There are advantages to programs and data using the same syntaxdata using the same syntax

Lisp’s Unusual SyntaxLisp’s Unusual Syntax

Lisp EvolutionLisp Evolution Quickly became, and remains, the Quickly became, and remains, the

most popular language for most popular language for AIAI applicationsapplications

Before 1980: many dialects in use:Before 1980: many dialects in use:• Each Each AIAI research group had its own dialect research group had its own dialect• In the 1970’s, a number of Lisp machines In the 1970’s, a number of Lisp machines

were developed, each with its own dialectwere developed, each with its own dialect

Today: some standardization:Today: some standardization:• Common Lisp: a large language and APICommon Lisp: a large language and API• Scheme: a smaller and simpler dialectScheme: a smaller and simpler dialect

Lisp InfluenceLisp Influence

22ndnd oldest general-purpose oldest general-purpose programming language still in useprogramming language still in use

Some ideas, like the conditional Some ideas, like the conditional expression and recursion, were expression and recursion, were adopted by Algol and later by many adopted by Algol and later by many other imperative languagesother imperative languages

Lisp InfluenceLisp Influence The function-oriented approach The function-oriented approach

influenced modern functional influenced modern functional languages like MLlanguages like ML

Garbage collection is increasingly Garbage collection is increasingly common in many different language common in many different language familiesfamilies

Lisp programmers know the value of Lisp programmers know the value of everything and the cost of nothingeverything and the cost of nothing

Alan PerlisAlan Perlis

Lisp is a programmable programming Lisp is a programmable programming language. language. John FoderaroJohn Foderaro

Lisp has jokingly been called "the most Lisp has jokingly been called "the most intelligent way to misuse a computer". intelligent way to misuse a computer".

Edsger DijkstraEdsger Dijkstra

LLots of ots of IIrritating rritating SSuperfluous uperfluous PParenthesesarentheses

ARPA 1962ARPA 1962Advanced Research Projects AgencyAdvanced Research Projects Agency

Formed for research not Formed for research not just military applicationsjust military applications

““LickLick” First director ” First director

He called it the:He called it the:IInformation nformation PProcessing rocessing TTechniques echniques OOffice (ffice (IPTOIPTO))

JCR LickliderJCR Licklider

Donald DaviesDonald Davies

British inventor of British inventor of packet switchingpacket switching

National Physical LaboratoryNational Physical Laboratory

19241924-2000-2000

Lick’sLick’s Intergalactic Network Intergalactic Network 19651965

With ARPA funding, Larry Roberts and With ARPA funding, Larry Roberts and Thomas Marill created first wide-area Thomas Marill created first wide-area network connection: MIT to Santa network connection: MIT to Santa Monica Monica

Dedicated telephone line with acoustic Dedicated telephone line with acoustic couplerscouplers

Telephone lines work for data, but areTelephone lines work for data, but are InefficientInefficient Wasteful of bandwidth Wasteful of bandwidth Expensive Expensive

As Kleinrock predicts, packet switching As Kleinrock predicts, packet switching offers the most promising model for offers the most promising model for communication between computers.communication between computers.

Joss 1965 Joss 1965 Johnniac Open Shop SystemJohnniac Open Shop System

The ARPA-funded at the The ARPA-funded at the RAND Corporation RAND Corporation

Computational problem solving at a number of Computational problem solving at a number of remote electric typewriter consolesremote electric typewriter consoles

IBM electric typewriters modified with small IBM electric typewriters modified with small boxes with indicator lights and activating boxes with indicator lights and activating switches switches

User input appeared in green, and JOSS User input appeared in green, and JOSS responded with output in black.responded with output in black.

Paul Baran Paul Baran

Envisioned a communications Envisioned a communications network that would survive a network that would survive a major enemy attacked major enemy attacked

October 29, 1969October 29, 1969

first host-to-host connection, first host-to-host connection, from UCLA to SRIfrom UCLA to SRI

first “Log-In” crashed the IMPs first “Log-In” crashed the IMPs (Interface Message Processors) (Interface Message Processors)

but the next “Log-In” worked! but the next “Log-In” worked!

19701970Nodes are added to the ARPANET at the Nodes are added to the ARPANET at the

rate of one per month rate of one per month

19711971

Metcalfe’s LawMetcalfe’s Law““The value of a The value of a network increases network increases exponentially with exponentially with the number of the number of nodes.” nodes.” Robert MetcalfeRobert Metcalfe

EthernetEthernetInvented 1973 at Xerox–PARCInvented 1973 at Xerox–PARCby Robert Metcalfe and David Boggsby Robert Metcalfe and David BoggsGot the idea of Got the idea of packetspackets from the from the

ALOHAnetALOHAnet packet packet maximum 1000 bits longmaximum 1000 bits long

recipients address attached to therecipients address attached to the head of each head of each packetpacket

computers tuned to UHF frequency, computers tuned to UHF frequency, listening for listening for packetspackets addressed to it addressed to it

Industry StandardIndustry Standard Metcalfe left Xerox in 1979 to promote Metcalfe left Xerox in 1979 to promote

the use of personal computers and Local the use of personal computers and Local Area Networks (LANs).Area Networks (LANs).

He convinced Digital Equipment, Intel, He convinced Digital Equipment, Intel, and Xerox Corporations to work together and Xerox Corporations to work together and promote ethernet as a standard.and promote ethernet as a standard.

Today, ethernet is the most widely Today, ethernet is the most widely installed LAN protocol.installed LAN protocol.

Ethernet is no longer limited to LANs.Ethernet is no longer limited to LANs.

ArpanetArpanetSuccessive levels of complexitySuccessive levels of complexity

1973 1977

Snowball effect Snowball effect startsstarts USENET - a series of shell scripts USENET - a series of shell scripts

by Steve Bellovin at UNC to by Steve Bellovin at UNC to communicate with Duke communicate with Duke

Newsgroups start with a name Newsgroups start with a name that gives an idea of its content that gives an idea of its content

USENET - early example of a USENET - early example of a client server, users dial in to a client server, users dial in to a server with requests to forward server with requests to forward certain newsgroup postings. certain newsgroup postings.

The server then ‘serves’ the The server then ‘serves’ the request.request.Computer magazine

September 1979

1980 1984

ArpanetArpanetSuccessive levels of complexitySuccessive levels of complexity

19831983 ARPANET wasARPANET was

standardizedstandardized on the TCP/IP on the TCP/IP protocols adopted by protocols adopted by the US Department of Defense. the US Department of Defense.

The Defense Communications Agency The Defense Communications Agency split the network into a public “ARPANET” split the network into a public “ARPANET” and a classified “MILNET” and a classified “MILNET”

Only 45 hosts remained on the ARPANET Only 45 hosts remained on the ARPANET

19831983 Numbering the Internet hosts and

keeping track of the host names fails to keep up with the growth of the Internet.

Development of the Domain Name System - user@host.domain

TimelineTimeline

19891989 Number of hosts Number of hosts

Jan/ 80,000Jan/ 80,000July/ 130,000 July/ 130,000 Nov/ 160,000Nov/ 160,000

Australia, Germany, Australia, Germany,

Israel, Italy, Japan, Israel, Italy, Japan, Mexico, Netherlands, Mexico, Netherlands, New Zealand and the New Zealand and the United Kingdom addedUnited Kingdom added

Tim Berners-Lee

Tim Berners-LeeTim Berners-Lee

Devised the URL (uniform Devised the URL (uniform resource locator)resource locator)

Created Hypertext Transfer Created Hypertext Transfer ProtocolProtocol(HTTP)(HTTP)

Defined HTMLDefined HTML

Everyday, garden Everyday, garden variety geniusvariety genius

Gopher – University of MinnesotaGopher – University of Minnesota Early Browsers Early Browsers Lynx & ViolaLynx & Viola

19931993 1995 1995 Mosaic Mosaic Netscape Netscape Mozilla Mozilla

19901990

•Ease of Hypercard•Full HTML capacity of WWW