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

Ten Computer Science Breakthroughs

Dr. Raymond GreenlawArmstrong Atlantic State

UniversitySchool of Computing

Dr. Raymond Greenlaw – Armstrong Atlantic State University – School of Computing 2

Outline• History of Computer Science• Turing Machines• Moore’s 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 subroutines

• 1935 – Alan Turing defines a model for computation


History of Computer Science• 1937 – Claude Shannon links Boolean

logic to digital circuit design• 1939 – Turing’s 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 intelligence

• 1956 – John McCarthy coins the term “artificial intelligence”


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 languages

• 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 sense


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 events

• 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 MM = (A, K, q0, δ), where A is the tape-alphabet, K is the finite set of states, q0 is the starting state, and δ 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

8 s1 1101

9 s2 1001


Moore’s Law


Moore’s 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


Moore’s 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) months

• Industry estimates show this will hold for several chip generations


Moore’s 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 Moore’s Law


Recursion


Recursion• 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


Recursion• A recursive algorithm is one that uses

itself in its own definition• Find the factorial of an integer:

function factorial(int x) {if (x < 0) return -1; // errorif (x==0) return 1;

return factorial(x-1) * x}

• factorial(3) returns 6, which equals 3!


NP-Completeness• NP is the class of problems that can

be solved on a nondeterministic Turing machine in polynomial time

• 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


NP-Completeness• 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


NP-Completeness• 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


NP-Completeness

NP-complete

NP

P


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 Time’s Man of the Year


Personal Computers• In the 1990s, personal processing

power increased greatly• 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 Institute


The Internet• In the 1970s, ARPANET was used by

the military, large companies like IBM, and universities (for email)

• 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 – AT&T Bell Labs developed UNIX to UNIX CoPy (UUCP)


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 It’s 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 NSF’s five supercomputing centers

• 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 Internet

• 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 million[1]

– Users (Nov. 2005): 972.8 million[2]

– Registered Domains (Dec. 2005): over 60 million active domains[3]

1. www.isc.org - Internet Service Consortium2. www.internetworldstats.com/stats.htm - Internet World Stats3. 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 public

• 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 classes

• 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 developer’s transition


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 platform

• 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 communication

• Wireless communication has allowed technology to penetrate areas where it previously couldn’t 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 2000


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


Conclusions• 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 haven’t 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.


References• 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, 1989.

• Multiple Articles, November 2005 <http://wikipedia.org>• 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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Ten Computer Science Breakthroughs Dr. Raymond Greenlaw Armstrong Atlantic State University School of Computing