catflap.org Online Dictionary Query

  Turing Machine
       
           A hypothetical machine defined in 1935-6 by
          Alan Turing and used for computability theory proofs.  It
          consists of an infinitely long "tape" with symbols (chosen
          from some finite set) written at regular intervals.  A
          pointer marks the current position and the machine is in one
          of a finite set of "internal states".  At each step the
          machine reads the symbol at the current position on the tape.
          For each combination of current state and symbol read, a
          program specifies the new state and either a symbol to write
          to the tape or a direction to move the pointer (left or right)
          or to halt.
       
          In an alternative scheme, the machine writes a symbol to the
          tape *and* moves at each step.  This can be encoded as a write
          state followed by a move state for the write-or-move machine.
          If the write-and-move machine is also given a distance to move
          then it can emulate an write-or-move program by using states
          with a distance of zero.  A further variation is whether
          halting is an action like writing or moving or whether it is a
          special state.
       
          [What was Turing's original definition?]
       
          Without loss of generality, the symbol set can be limited to
          just "0" and "1" and the machine can be restricted to start on
          the leftmost 1 of the leftmost string of 1s with strings of 1s
          being separated by a single 0.  The tape may be infinite in
          one direction only, with the understanding that the machine
          will halt if it tries to move off the other end.
       
          All computer instruction sets, high level languages and
          computer architectures, including parallel processors, can
          be shown to be equivalent to a Turing Machine and thus
          equivalent to each other in the sense that any problem that
          one can solve, any other can solve given sufficient time and
          memory.
       
          Turing generalised the idea of the Turing Machine to a
          "Universal Turing Machine" which was programmed to read
          instructions, as well as data, off the tape, thus giving rise
          to the idea of a general-purpose programmable computing
          device.  This idea still exists in modern computer design with
          low level microcode which directs the reading and decoding
          of higher level machine code instructions.
       
          A busy beaver is one kind of Turing Machine program.
       
          Dr. Hava Siegelmann of Technion reported in Science of 28
          Apr 1995 that she has found a mathematically rigorous class of
          machines, based on ideas from chaos theory and neural
          networks, that are more powerful than Turing Machines.  Sir
          Roger Penrose of Oxford University has argued that the brain
          can compute things that a Turing Machine cannot, which would
          mean that it would be impossible to create artificial
          intelligence.  Dr. Siegelmann's work suggests that this is
          true only for conventional computers and may not cover neural
          networks.
       
          See also Turing tar-pit, finite state machine.
       
          (1995-05-10)
       
       

  Turing machine
       n : a hypothetical computer with an infinitely long memory tape

  Turing machine /tjˈʊəɹɪŋ məʃˈiːn/
  Turingmaschine  [comp.]  [math.]

  Turing machine /tjˈʊəɹɪŋ məʃˈiːn/ 
  Turingin kone
  abstract machine

  Turing machine /tjˈʊəɹɪŋ məʃˈiːn/
  Turingov stroj

  turing machine /tjˈʊəɹɪŋ məʃˈiːn/
  mașină turing

  Turing machine
     [自]图灵机(指计算自动化的一种数学理想化机器)