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Ten Computer Science Breakthroughs


Ten Computer Science Breakthroughs Dr. Raymond Greenlaw Armstrong Atlantic State University School of Computing Outline History of Computer Science Turing Machines ... – PowerPoint PPT presentation

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Title: Ten Computer Science Breakthroughs

Ten Computer Science Breakthroughs
  • Dr. Raymond Greenlaw
  • Armstrong Atlantic State University
  • School of Computing

  • History of Computer Science
  • Turing Machines
  • Moores Law
  • Recursion
  • NP-Completeness
  • Personal Computers
  • The Internet
  • The Web
  • High-Level Languages
  • Handheld Wireless Devices
  • Human Genome Project

History of Computer Science
  • 1673 Gottfried Wilhelm von Leibniz invents a
    machine to do multiplication
  • 1821 Charles Babbage builds a machine to
    calculate exponential functions, begins designing
    Analytical Engine
  • 1832 Ada Lovelace begins writing programs (on
    punch cards) for the nonexistent Analytical
    Engine, inventing such concepts as loops and
  • 1935 Alan Turing defines a model for computation

History of Computer Science
  • 1937 Claude Shannon links Boolean logic to
    digital circuit design
  • 1939 Turings work plays a key role in breaking
    the Germans Enigma code machine
  • 1943 Small computers are being built in
    multiple countries
  • 1950 Turing proposes a test of machine
  • 1956 John McCarthy coins the term artificial

History of Computer Science
  • 1957 FORTRAN is released by John Backus and the
    IBM team
  • 1958 John McCarthy invents Lisp
  • 1959 John Backus and Peter Naur propose the use
    of context-free grammars to describe programming
  • 1961 Edsger Dijkstra applies the semaphore
    principle used in train signaling systems to
    mutual exclusion in computer operations

History of Computer Science
  • 1962 Donald Knuth begins work on The Art of
    Computer Programming
  • 1971 Alan Kay develops the first
    object-oriented programming language, Smalltalk
  • 1971 Stephen Cook publishes a paper on
    non-deterministic polynomial completeness
    (NP-completeness), defining a new family of
    problems that is not computable in a practical

History of Computer Science
  • 1973 Leonid Levin publishes a paper identifying
    the class of NP-complete problems independently
    of Cook (research was conducted in 1971)
  • 1977 Leslie Lamport defines a model of time for
    distributed systems based on a partial order of
  • 1980 Microsoft is founded, helping to push PCs
    into widespread use with the public

Turing Machines
Turing Machines
  • First conceived by Alan Turing in the mid-1930s
  • Formulated in an effort to write down in simplest
    terms what it means for a computation to proceed
    in discrete steps
  • Very robust, and Turing believed it was the most
    powerful conceivable theoretical model due to its
    equivalence to other models of computing

Turing Machines
  • Simplest and most widely used theoretical models
    of computing
  • Represented as a machine with
  • a tape consisting of admissible symbols, one to a
    cell (the tape alphabet)
  • a head that can read the current symbol, or
    replace it
  • and a finite control that can be in any one of a
    finite set of states
  • Machine can also move the tape, one cell at a
    time, to the left or right

Turing Machines
  • Given a set of consecutive symbols on the tape,
    the machine is positioned on the first non-blank
    symbol and begins to process
  • When the machine halts, whatever is on the tape
    is the output or result of the computation for
    the input
  • Can formally be defined as a 4-tuple M
  • M (A, K, q0, d), where A is the tape-alphabet,
    K is the finite set of states, q0 is the starting
    state, and d is the transition function

Turing Machines
  • Bold denotes head position

Old St. Read Write Move New St.
s1 1 0 R s2
s2 1 1 R s2
s2 0 0 R s3
s3 0 1 L s4
s3 1 1 R s3
s4 1 1 L s4
s4 0 0 L s5
s5 1 1 L s5
s5 0 1 R s1
Step St. Tape Step St. Tape
1 s1 11 10 s3 1001
2 s2 01 11 s3 10010
3 s2 010 12 s4 10011
4 s3 0100 13 s4 10011
5 s4 0101 14 s5 10011
6 s5 0101 15 s1 11011
7 s5 0101 Halt Halt Halt
8 s1 1101 Halt Halt Halt
9 s2 1001 Halt Halt Halt
Moores Law
Moores Law
  • Rule of thumb in the computing industry about the
    growth of computing power
  • Gordon E. Moore, co-founder of Intel, stated the
    growth of computing power follows an empirical
    exponential law in an April 1965 article in
    Electronics Magazine
  • Originally, he proposed a 12-month doubling, then
    a 24-month doubling
  • The more it became accepted, this statement began
    to serve as a goal for the industry

Moores Law
  • The least rigorous interpretation is that
    computing power per unit cost will continue to
    grow exponentially
  • The most rigorous interpretation states that the
    total number of transistors on the cheapest CPU
    will grow exponentially at a constant rate and
    that this constant rate produces a doubling every
    12 (or 18 (as he is often misquoted), or 24)
  • Industry estimates show this will hold for
    several chip generations

Moores Law
  • At the end of the 1970s, Moore's Law became known
    as the limit for the number of transistors on the
    most complex chips
  • However, it is also common to cite Moore's law to
    refer to the rapidly continuing advance in
    computing power per unit cost
  • As consumer computer costs decline, it is getting
    more expensive for manufacturers to continue
    achieving Moores Law

  • The invocation of a computation inside an
    identical computation that is already in progress
  • Used by defining a base case, then defining rules
    to break down complex cases into simpler cases
    using a divide-and-conquer approach
  • They break the problem into several subproblems
    that are similar to the original problem, but
    smaller in size

  • A recursive algorithm is one that uses itself in
    its own definition
  • Find the factorial of an integer
  • function factorial(int x)
  • if (x lt 0) return -1 // error
  • if (x0) return 1
  • return factorial(x-1) x
  • factorial(3) returns 6, which equals 3!

  • NP is the class of problems that can be solved on
    a nondeterministic Turing machine in polynomial
  • Complete problems are the computationally most
    difficult problems to solve in a given class
  • NP-completeness problems are the most difficult
    problems to solve in the class NP

  • P is the class of problems that can be solved in
    polynomial time on a deterministic Turing machine
  • The problems in P are considered feasibly
    solvable on personal computers
  • It is conjectured that P ? NP
  • This conjecture implies no NP-complete problem is
    in the class P
  • Therefore, problems that are NP-complete are
    considered intractable

  • Examples of NP-complete problems are
    Satisfiability, Traveling Salesman Problem, and
    Graph Coloring
  • Many polynomial time approximate algorithms have
    been developed for problems that are NP-complete

Personal Computers
Personal Computers
  • Mini-computers (non-mainframe) computers became
    popular in research labs
  • In the mid-1970s microprocessor computers began
    to become popular
  • People used these machines to experiment with
    programming, play games, or run
    office/productivity applications
  • In 1982, the personal computer was named Times
    Man of the Year

Personal Computers
  • In the 1990s, personal processing power increased
  • This allowed computers to become more prevalent
  • Higher-end computers are now distinguished from
    home computers by their reliability, as opposed
    to raw power
  • Computers in every home allowed more people to
    get interested in programming and other aspects
    of computer science

Personal Computers
  • The term PC is often used to describe IBM
    compatible computers, the first batch of
    computers to reach consumers
  • This term has now been expanded to include
    products by companies like Apple, although they
    prefer not to be included because of the implied
    relationship to IBM PCs

The Internet
The Internet
  • The global system of networked computers together
    with their users and data
  • 1969 ARPANET was started by the Department of
    Defense to enable researchers to share
    super-computing power
  • Initially only four nodes, at the University of
    California at Los Angeles, UC at Santa Barbara,
    University of Utah, and the Stanford Research

The Internet
  • In the 1970s, ARPANET was used by the military,
    large companies like IBM, and universities (for
  • Local Area Networks became more prevalent and an
    open design was proposed
  • 1972 Nodes existed in England, and there were a
    total of 23, Ray Tomlinson invented email
  • 1976 ATT Bell Labs developed UNIX to UNIX CoPy

The Internet
  • 1979 User Network (USENET) was started by using
    UUCP to connect Duke and the University of North
    Carolina at Chapel Hill which allowed newsgroups
    to emerge
  • 1980 The Computer Science Network (CSNET)
    connected all university Computer Science
    departments in the U.S.
  • 1981 The Because Its Time Network (BITNET)
    formed at the City University of New York
    spawning many mailing lists

The Internet
  • 1983 The U.S. Defense Communications Agency
    requires that all ARPANET hosts use TCP/IP
    allowing computers to communicate easily
  • 1985 The National Science Foundation Network
    (NSFNET) connects the NSFs five supercomputing
  • 1988 The Internet Worm is released, infecting
    10 percent of all Internet hosts, this same year,
    Internet Relay Chat is written by Jarkko Oikarinen

The Internet
  • 1989 NSF takes control of ARPANET in a largely
    transparent move
  • The number of hosts at this time is over 100,000
  • 1991 Gopher is developed at the University of
    Minnesota, allowing the retrieval of files on the
  • The Internet ends up spawning massive amounts of
    information sharing and connectivity for people
    spread across the country

The Internet
  • Current Internet stats
  • Hosts (July 2005) 353.3 million1
  • Users (Nov. 2005) 972.8 million2
  • Registered Domains (Dec. 2005) over 60 million
    active domains3
  • www.isc.org - Internet Service Consortium
  • www.internetworldstats.com/stats.htm - Internet
    World Stats
  • www.whois.sc/internet-statistics/ - Whois Source

The Web
The Web
  • 1991 Tim Berners-Lee at CERN (a French acronym
    for the European Laboratory for Particle Physics)
    invents the World Wide Web (WWW) as a simple way
    to publish information and make it available on
    the Internet
  • 1992 WWW becomes publicly available to the
  • 1993 Mosiac, a graphical browser for the Web
    was released by Marc Andreessen and other
    graduate students at U. Illinois

The Web
  • 1994 Netscape Communications, formed by Marc
    Andreessen and Jim Clark, releases Netscape
    Navigator, a Web Browser that becomes widely used
  • 1994 Stanford graduate students David Filo and
    Jerry Yang develop a search engine and directory
    called Yahoo!
  • 1995 Sun releases Java, initially for
    interactive Web pages
  • 1995 Microsoft commits many resources to
    Internet Explorer

The Web
  • 1995 Courses about the Internet begin to be
    offered in colleges
  • 1998 Netscape releases the source code for
    their browser
  • 1998 Google, founded by Larry Page and Sergey
    Brin, incorporates. Started as a research
    project in 1996 at Stanford steadily becomes a
    leader on the Web, with a revenue of over 3
    billion in 2004
  • 2005 Google claims unique index of over 8
    billion pages

High-Level Languages
High-Level Languages
  • A programming language that is more
    user-friendly, to some extent platform-independent
    , and abstract from low-level computer processor
    operations such as memory accesses
  • Originally, programmers only had access to
    machine instructions specific to the computer
    with which they were working
  • This led to machine-specific code and lots of
    time spent learning languages that could only be
    used sparingly

High-Level Languages
  • Often has built in functions to perform tasks
    like input and output
  • Contains constructs that help reduce the
    complexity of formulating solutions to problems
  • Abstracts many of the ideas that need to be
    expressed in code
  • This allows for code reuse and extensibility
  • High-level languages began to come into being in
    the 1950s

High-Level Languages
  • FORTRAN was one of the first widely-adopted
    high-level languages, it was designed by John
    Backus at IBM and implemented in 1957
  • ALGOL 58 was invented in 1958 through
    international efforts
  • 1960 COBOL (COmmon Business Oriented Language)
    is introduced in 1960
  • 1964 BASIC (Beginner's All-purpose Symbolic
    Instruction Code) is implemented, originally
    devised by Kemenry and Kurtz

High-Level Languages
  • 1972 C developed by Ken Thompson and Dennis
    Ritchie for use on UNIX
  • 1983 C is released by Bjarne Stroustroup as
    an enhancement to C, originally called C with
  • 1995 Java is made public. Developed by James
    Gosling and other associates at Sun it is an
    object-oriented language
  • 2000 C from Microsoft is developed it is
    based on C and Java to ease developers

Handheld Wireless Devices
Handheld Wireless Devices
  • With the miniaturization of components, handheld
    devices have become more and more ubiquitous
  • Personal Digital Assistant (PDA) was coined by
    John Sculley at the Consumer Electronics Show in
    January 1992
  • Currently, the leading companies in PDAs are
    Palm, Microsoft, and Blackberry
  • These devices started with small, simple
    applications like day planners and address books

Handheld Wireless Devices
  • Sculley predicted that handheld devices would
    become ubiquitous tools that would hold phone
    numbers, calendars, notes, and send and receive
    data wirelessly
  • 1993 Apple introduces the first PDA, the
    Newton, which provided a small subset of the
    features Sculley predicted
  • 1996 Palm releases the PalmPilot which does
    everything Sculley predicted except wireless
    communication, would later release the Palm VII,
    adding wireless

Handheld Wireless Devices
  • Most of these devices run off a variation of the
    ARM architecture
  • Many PDAs have experienced a convergence towards
    mobile phones that include many of the original
    PDA features, but also provide phone service
  • A big component in widespread use was the
    wireless capabilities that eventually reached the
  • Wireless communication allows for devices to
    communicate over the air

Handheld Wireless Devices
  • Early form of wireless communication was over IR
    (infrared) but is now more commonly seen as
    Bluetooth, or other methods of short-range
  • Wireless communication has allowed technology to
    penetrate areas where it previously couldnt be
    used effectively
  • This has also allowed users to accomplish more
    things away from their offices and homes

Human Genome Project
Human Genome Project
  • An endeavor to map the human genome down to the
    base pair level and to identify all genes present
  • Launched in 1986 by Charles DeLisi
  • Formally founded in 1990 by the U.S. Department
    of Energy and the U.S. National Institutes of
    Health, was expected to take 15 years
  • A rough draft of the human genome was released in

Human Genome Project
  • A private group, Celera Genomics, was also
    working on the project at the same time
  • On April 14, 2003, a joint press release from
    both groups announced that 99 of the genome was
    sequenced with 99.99 accuracy
  • The sequence of human DNA is stored in a publicly
    accessible database called Genbank

Human Genome Project
  • The HGP harnessed computing power and techniques
    to help accomplish their goals
  • This project pushed bioinformatics to the
    forefront, a field that many believe will be
    where the majority of new breakthroughs will occur

  • This list is only a small sampling of
    breakthroughs that have contributed greatly to
    the field of computer science. We would like to
    thank the many other computer scientists who
    havent been recognized, but have given greatly
    to our pool of knowledge. The future is bright,
    there are many active fields of research, and we
    look forward to acknowledging other breakthroughs
    in computer science.

  • Cormen, Thomas, et. al. Introduction to
    Algorithms. United States McGraw-Hill Book
    Company, 2001.
  • Dewdney, A.K. The New Turing Omnibus. New York
    Henry Holt and Company, 1989.
  • Greenlaw, Raymond and Ellen Hepp. Inline/Online
    Fundamentals of the Internet and the World Wide
    Web. United States McGraw-Hill, 1999.
  • Gurari, Ethan. An Introduction to The Theory of
    Computation. Maryland Computer Science Press,
  • Multiple Articles, November 2005
  • Shasha, Dennis Elliott. Out of their minds the
    lives and discoveries of 15 great computer
    scientists. New York Copernicus, 1995.
  • Tourlakis, George J. Computability. Reston
    Reston Publishing Company, Inc., 1984.
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