Time/space SAT Tradeoff
Currently we have no way to prove that Boolean satisfiability problem (often abbreviated as SAT), which is NP-complete, requires exponential (or at least super-polynomial) time (this is the famous P versus NP problem), or linear (or at least super-logarithmic) space to solve. However, in the context of space-time tradeoff, one can prove that SAT cannot be computed if we apply constraints to both time and space. L. Fortnow, Lipton, D. van Melkebeek, and A. Viglas proved that SAT cannot be computed by a Turing machine that takes at most O steps and at most O cells of its read-write tapes.
Read more about this topic: Richard J. Lipton
Famous quotes containing the words time, space and/or sat:
“In the actual world—the painful kingdom of time and place—dwell care, and canker, and fear. With thought, with the ideal, is immortal hilarity, the rose of joy.”
—Ralph Waldo Emerson (1803–1882)
“Not so many years ago there there was no simpler or more intelligible notion than that of going on a journey. Travel—movement through space—provided the universal metaphor for change.... One of the subtle confusions—perhaps one of the secret terrors—of modern life is that we have lost this refuge. No longer do we move through space as we once did.”
—Daniel J. Boorstin (b. 1914)
“Others apart sat on a Hill retir’d,
In thoughts more elevate, and reason’d high
Of Providence, Foreknowledge, Will, and Fate,
Fixt Fate, free will, foreknowledge absolute,
And found no end, in wandring mazes lost.
Of good and evil much they argu’d then,
Of happiness and final misery,
Passion and Apathie, and glory and shame,
Vain wisdom all, and false Philosophie:”
—John Milton (1608–1674)