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  2. Year 2038 problem - Wikipedia

    en.wikipedia.org/wiki/Year_2038_problem

    The problem is similar in nature to the year 2000 problem, the difference being the Year 2000 problem had to do with base 10 numbers, whereas the Year 2038 problem involves base 2 numbers. Analogous storage constraints will be reached in 2106 , where systems storing Unix time as an unsigned (rather than signed) 32-bit integer will overflow on 7 ...

  3. Time travel - Wikipedia

    en.wikipedia.org/wiki/Time_travel

    The first page of The Time Machine published by Heinemann. Time travel is the hypothetical activity of traveling into the past or future. Time travel is a concept in philosophy and fiction, particularly science fiction. In fiction, time travel is typically achieved through the use of a device known as a time machine. The idea of a time machine ...

  4. EXPTIME - Wikipedia

    en.wikipedia.org/wiki/EXPTIME

    In computational complexity theory, the complexity class EXPTIME (sometimes called EXP or DEXPTIME) is the set of all decision problems that are solvable by a deterministic Turing machine in exponential time, i.e., in O(2 p(n)) time, where p(n) is a polynomial function of n.

  5. Quantum mechanics of time travel - Wikipedia

    en.wikipedia.org/wiki/Quantum_mechanics_of_time...

    Researchers have explored Deutsch's ideas further. If feasible, his model might allow computers near a time machine to solve problems beyond classical capabilities; however, debates about CTCs' feasibility continue. [15] [16] Despite its theoretical nature, Deutsch's proposal has faced significant criticism. [17]

  6. Complexity class - Wikipedia

    en.wikipedia.org/wiki/Complexity_class

    Put another way, in the definition of the class NP (the set of decision problems for which the problem instances, when the answer is "YES", have proofs verifiable in polynomial time by a deterministic Turing machine) is a proof system in which the proof is constructed by an unmentioned prover and the deterministic Turing machine is the verifier.

  7. NP (complexity) - Wikipedia

    en.wikipedia.org/wiki/NP_(complexity)

    NP is the set of decision problems solvable in polynomial time by a nondeterministic Turing machine. NP is the set of decision problems verifiable in polynomial time by a deterministic Turing machine. The first definition is the basis for the abbreviation NP; "nondeterministic, polynomial time". These two definitions are equivalent because the ...

  8. Time hierarchy theorem - Wikipedia

    en.wikipedia.org/wiki/Time_hierarchy_theorem

    Informally, these theorems say that given more time, a Turing machine can solve more problems. For example, there are problems that can be solved with n 2 time but not n time, where n is the input length. The time hierarchy theorem for deterministic multi-tape Turing machines was first proven by Richard E. Stearns and Juris Hartmanis in 1965. [1]

  9. P versus NP problem - Wikipedia

    en.wikipedia.org/wiki/P_versus_NP_problem

    there exists a polynomial-time Turing machine that halts with f(w) on its tape on any input w. Alternatively, if L ∈ NP, and there is another NP-complete problem that can be polynomial-time reduced to L, then L is NP-complete. This is a common way of proving some new problem is NP-complete.