Artificial Intelligence

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Artificial Intelligence
Dartmouth College

• AI conference at DartmouthCollege, 1956
  McCarthy,Minsky, Newell, Simon
• Newell, Shaw and Simon demonstrated Logic
  Theorist, a reasoning program written in IPL
  (Information Processing Language)
• IPL had support for linked lists, and caught
  McCarthys attention

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Early AI Language Efforts

• He wanted a language for AI projects, but not
  IPL too low-level and machine-specific
• An IBM group (consulting McCarthy)
  developedFLPL Fortran List Processing Language

John McCarthy
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• McCarthys wish list, developed while writing AI
  programs (chess and differential calculus)
• Conditional expressions
• Recursion
• Higher-order functions (like MLs map)
• Garbage collection
• FLPL was not the answer for McCarthys group at
  MIT in 1958

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Lisps Unusual Syntax

• A Lisp program is a list representing an AST
  ( a ( b c))
• The plan was to use some Fortran-like notation
• But McCarthy wrote a paper showing a simple Lisp
  interpreter in Lisp a function called eval
• To avoid syntax issues, he used the list-AST
  form, both for evals input and for eval itself
• This eval, hand-translated into assembly
  language, became the first implementation of Lisp

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Lisps Unusual Syntax

• The group never gave up the idea of compiling
  from some Fortran-like syntax
• But they never did it either
• Later, people tried to compile Lisp from a
  Fortran- or Algol-like syntax
• None of these efforts were very popular
• There are advantages to programs and data using
  the same syntax

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Lisp Evolution

• Quickly became, and remains, the most popular
  language for AI applications
• Before 1980 many dialects in use
• Each AI research group had its own dialect
• In the 1970s, a number of Lisp machines were
  developed, each with its own dialect
• Today some standardization
• Common Lisp a large language and API
• Scheme a smaller and simpler dialect

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Lisp Influence

• 2nd oldest general-purpose programming language
  still in use
• Some ideas, like the conditional expression and
  recursion, were adopted by Algol and later by
  many other imperative languages

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Lisp Influence

• The function-oriented approach influenced modern
  functional languages like ML
• Garbage collection is increasingly common in many
  different language families

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Lots of Irritating Superfluous Parentheses

• Lisp programmers know the value of everything and
  the cost of nothing Alan Perlis
• Lisp is a programmable programming language.
  John Foderaro
• Lisp has jokingly been called "the most
  intelligent way to misuse a computer".
  Edsger Dijkstra

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ARPA 1962Advanced Research Projects Agency

• Formed for research not just military
  applications
• Lick First director
• He called it theInformation Processing
  Techniques Office (IPTO)

JCR Licklider
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Donald Davies

• British inventor of packet switching
• National Physical Laboratory

1924-2000
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Licks Intergalactic Network 1965

• With ARPA funding, Larry Roberts and Thomas
  Marill created first wide-area network
  connection MIT to Santa Monica
• Dedicated telephone line with acoustic couplers
• Telephone lines work for data, but are ?
  Inefficient ? Wasteful of bandwidth ? Expensive
• As Kleinrock predicts, packet switching offers
  the most promising model for communication
  between computers.

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Joss 1965 Johnniac Open Shop System

• The ARPA-funded at the RAND Corporation
• Computational problem solving at a number of
  remote electric typewriter consoles
• IBM electric typewriters modified with small
  boxes with indicator lights and activating
  switches
• User input appeared in green, and JOSS responded
  with output in black.

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Paul Baran

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

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October 29, 1969

• first host-to-host connection, from UCLA to SRI
• first Log-In crashed the IMPs (Interface
  Message Processors)
• but the next Log-In worked!

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1970

• Nodes are added to the ARPANET at the rate of
  one per month

1971
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Metcalfes Law

• The value of a network increases exponentially
  with the number of nodes. Robert Metcalfe

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Ethernet

• Invented 1973 at XeroxPARCby Robert Metcalfe
  and David Boggs
• Got the idea of packets from the ALOHAnet
• ? packet maximum 1000 bits long
• ? recipients address attached to the head
  of each packet
• ? computers tuned to UHF frequency,
  listening for packets addressed to it

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Industry Standard

• Metcalfe left Xerox in 1979 to promote the use of
  personal computers and Local Area Networks
  (LANs).
• He convinced Digital Equipment, Intel, and Xerox
  Corporations to work together and promote
  ethernet as a standard.
• Today, ethernet is the most widely installed LAN
  protocol.
• Ethernet is no longer limited to LANs.

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ArpanetSuccessive levels of complexity
1977
1973
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Snowball effect starts

• USENET - a series of shell scripts by Steve
  Bellovin at UNC to communicate with Duke
• Newsgroups start with a name that gives an idea
  of its content
• USENET - early example of a client server, users
  dial in to a server with requests to forward
  certain newsgroup postings.
• The server then serves the request.

Computer magazine September 1979
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ArpanetSuccessive levels of complexity
1980
1984
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1983

• ARPANET wasstandardized on the TCP/IP
  protocols adopted by the US Department of
  Defense.
• The Defense Communications Agency split the
  network into a public ARPANET and a classified
  MILNET
• Only 45 hosts remained on the ARPANET

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1983

• 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_at_host.domain

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Timeline
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1989
Tim Berners-Lee

• Number of hosts Jan/ 80,000July/ 130,000 Nov/
  160,000
• Australia, Germany, Israel, Italy, Japan, Mexico,
  Netherlands, New Zealand and the United Kingdom
  added

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Tim Berners-Lee

• Devised the URL (uniform resource locator)
• Created Hypertext Transfer Protocol(HTTP)
• Defined HTML

Everyday, garden variety genius
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1990

• Gopher University of Minnesota
• Early Browsers Lynx Viola
• 1993 1995
• Mosaic ? Netscape ? Mozilla

• Ease of Hypercard
• Full HTML capacity of WWW

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