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Future Computers. http://en.wikipedia.org/wiki/Alan_Turing http://en.wikipedia.org/wiki/Enigma_machine http://en.wikipedia.org/wiki/John_von_Neumann. Alan Turing. 23 June 1912 – 7 June 1954 English mathematician Logician cryptanalyst and computer scientist. Alan Turing.
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http://en.wikipedia.org/wiki/Alan_Turing • http://en.wikipedia.org/wiki/Enigma_machine • http://en.wikipedia.org/wiki/John_von_Neumann
Alan Turing • 23 June 1912 – 7 June 1954 • English mathematician • Logician • cryptanalyst and • computer scientist
Alan Turing • For a time he was head of Hut 8, the section responsible for German naval cryptanalysis during World War II • An Enigma machine is any of a family of related electro-mechanical rotor machines used for the encryption and decryption of secret messages, the German military model, the • Wehrmacht Enigma, • is the version most commonly discussed.
Alan Turing • Together with Gordon Welchman designed La Bombe that could break any Enigma-enciphered message • The basic property of the Bombe was that it could break any Enigma-enciphered message, provided that the hardware of the Enigma was known and that a plain-text 'crib' of about 20 letters could be guessed accurately • After the war he worked at the National Physical Laboratory, where he created one of the first designs for a stored-program computer, the ACE.
Touring Machine 1936 • Execution. Initially the Turing machine starts in one distinguished state called the start state, and the tape head points to one distinguished cell called the start cell. • There is at most one possible transition corresponding to each combination of state and input symbol; thus, the actions of the machine are completely determined in advance.
http://www.cs.princeton.edu/introcs/74turing/ • http://www.cs.princeton.edu/introcs/turing/turing.jnlp • Turing Machine
Touring Machine 1936 • Read the input symbol from the active cell. • Look up the transition rule associated with the current state and input symbol. • Overwrite the input symbol with the new symbol. • Change the current state according to the transition rule. • Shift the tape head one cell to the left or right, according to the new state's designation.
Universal Turing Machine • "It is possible to invent a single machine which can be used to compute any computable sequence. If this machine U is supplied with a tape on the beginning of which is written the S.D ["standard description" of an action table] of some computing machine M, then U will compute the same sequence as M."
John Von Neumann • December 28, 1903 – February 8, 1957 • Made major contributions to: • Set theory, • Functional analysis, • Quantum mechanics, • Ergodic theory, • Continuous geometry, • Economics • Computer science, • Numerical analysis, • Hydrodynamics
John Von Neumann • Von Neumann distinguished himself from his peers in childhood for having a photographic memory, being able to memorize and recite back a page out of a phone book in a few minutes. Science, history, and psychology were among his many interests; he succeeded in every academic subject in school.
John Von Neumann • He published his first mathematical paper in collaboration with his tutor at the age of eighteen, and resolved to study mathematics in college.
Alonzo Church • June 14, 1903 – August 11, 1995 • American mathematician and logician • Made major contributions to: • Mathematical logic and the • Foundations of theoretical computer science
Alonzo Church • He is best known for the lambda calculus, • is a formal system for function definition, function application and recursion • smallest universal programming language of the World • It is equivalent to Turing machines. However, it emphasizes the use of transformation rules and does not care about the actual machine implementing them • Church–Turing thesis, • Frege–Church ontology, and the • Church–Rosser theorem.
Church–Turing Thesis • Informally it states that if an algorithm (a procedure that terminates) exists then there is an equivalent • Turing machine, • recursively-definable function, • or applicable λ-function, • for that algorithm. • Today the thesis has near-universal acceptance
Modern Computers • Von Neumann Machine implement a universal Turing machine and have a sequential architecture • Modern Computers are based on John Von Neumann architecture • Modern Computers are based on 1936 architecture
Travelling salesman problem • The Travelling Salesman Problem (TSP) is a problem in combinatorial optimization studied in operations research and theoretical computer science. Given a list of cities and their pairwise distances, the task is to find a shortest possible tour that visits each city exactly once. • http://en.wikipedia.org/wiki/Travelling_salesman_problem
Travelling salesman problem • The most direct solution would be to try all permutations (ordered combinations) and see which one is cheapest (using brute force search). The running time for this approach lies within a polynomial factor of O(n!), the factorial of the number of cities, so this solution becomes impractical even for only 20 cities. • One of the earliest applications of dynamic programming is an algorithm that solves the problem in time O(n22n)
New Computer Paradigm • Superposition
New Computer Paradigm • In 1982, the Nobel prize-winning physicist Richard Feynman thought up the idea of a 'quantum computer', a computer that uses the effects of quantum mechanics to its advantage. • Quantum Computers use non classic logic operations to perform numeric calculations. • The advantage of Quantum Computers derives from their capabilities to execute multiple operations simultaneously on a single computer. • The Quantum Computers are inspired on Quantum Mechanics.
New Computer Paradigm • “I think it is safe to say that no one understands Quantum Mechanics. … What I am going to tell you about is what we teach our physics students in the third or fourth year of graduate school... • It is my task to convince you not to turn away because you don't understand it. You see my physics students don't understand it. ... That is because I don't understand it. Nobody does. (Richard Feynman)
David Deutsch’s Algorithm • Compute in a single step:
Different Computer Paradigm • Quantum algorithms will probably be used in computers within a 10 year range; there are several efficient algorithms already developed and many to come. Following we will show some interesting comparisons that would will help to illustrate the importance of these developments:
Dr. Quantum • http://www.youtube.com/watch?v=DfPeprQ7oGc