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In this paper, we consider Turing machines based on unsharp quantum logic. For a lattice-ordered quantum multiple-valued (MV) algebra E, we introduce E-valued non-deterministic Turing machines (ENTMs) and E-valued deterministic Turing…

Logic in Computer Science · Computer Science 2012-10-04 Yun Shang , Xian Lu , Ruqian Lu

Stochastic languages are the languages recognized by probabilistic finite automata (PFAs) with cutpoint over the field of real numbers. More general computational models over the same field such as generalized finite automata (GFAs) and…

Formal Languages and Automata Theory · Computer Science 2014-12-23 Arseny M. Shur , Abuzer Yakaryilmaz

This paper initiates the study of quantum computing within the constraints of using a polylogarithmic ($O(\log^k n), k\geq 1$) number of qubits and a polylogarithmic number of computation steps. The current research in the literature has…

Quantum Physics · Physics 2007-05-23 Sanjay Gupta , R. K. P. Zia

Polynomial-time quantum Turing machines are provably superior to their classical counterparts within a common space bound in $o(\log \log n)$. For $\Omega(\log \log n)$ space, the only known quantum advantage result has been the fact…

Computational Complexity · Computer Science 2026-01-26 A. C. Cem Say

While quantum computers hold the promise of significant computational speedups, the limited size of early quantum machines motivates the study of space-bounded quantum computation. We relate the quantum space complexity of computing a…

Quantum Physics · Physics 2019-08-30 Stacey Jeffery

We define formally decohered quantum computers (using density matrices), and present a simulation of them by a probabalistic classical Turing Machine. We study the slowdown of the simulation for two cases: (1) sequential quantum computers,…

Quantum Physics · Physics 2007-05-23 Dorit Aharonov , Michael Ben-Or

Continuing the study of complexity theory of Koepke's Ordinal Turing Machines (OTMs) that was started by Rin, L\"owe and the author, we prove the following results: (1) An analogue of Ladner's theorem for OTMs holds: That is, there are…

Logic · Mathematics 2026-05-19 Merlin Carl

A digital computer is generally believed to be an efficient universal computing device; that is, it is believed able to simulate any physical computing device with an increase in computation time of at most a polynomial factor. This may not…

Quantum Physics · Physics 2017-02-20 Peter W. Shor

Machine-learning tasks frequently involve problems of manipulating and classifying large numbers of vectors in high-dimensional spaces. Classical algorithms for solving such problems typically take time polynomial in the number of vectors…

Quantum Physics · Physics 2013-11-06 Seth Lloyd , Masoud Mohseni , Patrick Rebentrost

Deterministic one-way time-bounded multi-counter automata are studied with respect to their ability to perform reversible computations, which means that the automata are also backward deterministic and, thus, are able to uniquely step the…

Formal Languages and Automata Theory · Computer Science 2022-09-01 Martin Kutrib , Andreas Malcher

We consider a general class of decision problems concerning formal languages, called ``(one-dimensional) unboundedness predicates'', for automata that feature reversal-bounded counters (RBCA). We show that each problem in this class reduces…

Formal Languages and Automata Theory · Computer Science 2023-01-25 Pascal Baumann , Flavio D'Alessandro , Moses Ganardi , Oscar Ibarra , Ian McQuillan , Lia Schütze , Georg Zetzsche

Using nonstandard analysis, we will extend the classical Turing machines into the internal Turing machines. The internal Turing machines have the capability to work with infinite ($*$-finite) number of bits while keeping the finite…

Mathematical Physics · Physics 2007-05-23 Ken Loo

Due to the limitation on computational power of existing computers, the polynomial time does not works for identifying the tractable problems in big data computing. This paper adopts the sublinear time as the new tractable standard to…

Computational Complexity · Computer Science 2019-12-06 Xiangyu Gao , Jianzhong Li , Dongjing Miao , Xianmin Liu

We show that one can approximate the least fixed point solution for a multivariate system of monotone probabilistic polynomial equations in time polynomial in both the encoding size of the system of equations and in log(1/\epsilon), where…

Computational Complexity · Computer Science 2013-02-21 Kousha Etessami , Alistair Stewart , Mihalis Yannakakis

The {\em diagonalization technique} was invented by Georg Cantor to show that there are more real numbers than algebraic numbers and is very crucial in {\em theoretical computer science}. In this work, we enumerate all of the…

Computational Complexity · Computer Science 2025-06-03 Tianrong Lin

We introduce the notion of universal memcomputing machines (UMMs): a class of brain-inspired general-purpose computing machines based on systems with memory, whereby processing and storing of information occur on the same physical location.…

Neural and Evolutionary Computing · Computer Science 2015-12-17 Fabio L. Traversa , Massimiliano Di Ventra

Recently Shor showed how to perform fault tolerant quantum computation when the error probability is logarithmically small. We improve this bound and describe fault tolerant quantum computation when the error probability is smaller than…

Quantum Physics · Physics 2008-02-03 Dorit Aharonov , Michael Ben-Or

This paper develops general space-efficient methods for error reduction for unitary quantum computation. Consider a polynomial-time quantum computation with completeness $c$ and soundness $s$, either with or without a witness (corresponding…

Polylogarithmic time delineates a relevant notion of feasibility on several classical computational models such as Boolean circuits or parallel random access machines. As far as the quantum paradigm is concerned, this notion yields the…

Logic in Computer Science · Computer Science 2025-07-22 Florent Ferrari , Emmanuel Hainry , Romain Péchoux , Mário Silva

We examine the minimum amount of memory for real-time, as opposed to one-way, computation accepting nonregular languages. We consider deterministic, nondeterministic and alternating machines working within strong, middle and weak space, and…

Computational Complexity · Computer Science 2013-05-09 Abuzer Yakaryilmaz , A. C. Cem Say