Additional Details Required To Visualize or Implement Turing Machines
In the words of van Emde Boas (1990), p. 6: "The set-theoretical object provides only partial information on how the machine will behave and what its computations will look like."
For instance,
- There will need to be many decisions on what the symbols actually look like, and a failproof way of reading and writing symbols indefinitely.
- The shift left and shift right operations may shift the tape head across the tape, but when actually building a Turing machine it is more practical to make the tape slide back and forth under the head instead.
- The tape can be finite, and automatically extended with blanks as needed (which is closest to the mathematical definition), but it is more common to think of it as stretching infinitely at both ends and being pre-filled with blanks except on the explicitly given finite fragment the tape head is on. (This is, of course, not implementable in practice.) The tape cannot be fixed in length, since that would not correspond to the given definition and would seriously limit the range of computations the machine can perform to those of a linear bounded automaton.
Read more about this topic: Turing Machine
Famous quotes containing the words additional, details, required, visualize and/or machines:
“The mere existence of an additional child or children in the family could signify Less. Less time alone with parents. Less attention for hurts and disappointments. Less approval for accomplishments. . . . No wonder children struggle so fiercely to be first or best. No wonder they mobilize all their energy to have more or most. Or better still, all.”
—Adele Faber (20th century)
“Working women today are trying to achieve in the work world what men have achieved all along—but men have always had the help of a woman at home who took care of all the other details of living! Today the working woman is also that woman at home, and without support services in the workplace and a respect for the work women do within and outside the home, the attempt to do both is taking its toll—on women, on men, and on our children.”
—Jeanne Elium (20th century)
“In properly organized groups no faith is required; what is required is simply a little trust and even that only for a little while, for the sooner a man begins to verify all he hears the better it is for him.”
—George Gurdjieff (c. 1877–1949)
“Dear friend,
please do not think
that I visualize guitars playing
or my father arching his bone.
I do not even expect my mother’s mouth.
I know that I have died before....”
—Anne Sexton (1928–1974)
“The machine has had a pernicious effect upon virtue, pity, and love, and young men used to machines which induce inertia, and fear, are near impotents.”
—Edward Dahlberg (1900–1977)