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We prove in this paper that there is a language $L_s$ accepted by some nondeterministic Turing machine that runs within time $O(n^k)$ for any positive integer $k\in\mathbb{N}_1$ but not by any ${\rm co}\mathcal{NP}$ machines. Then we…

Computational Complexity · Computer Science 2026-05-29 Tianrong Lin

We consider the problem of minimising the number of states in a multiplicity tree automaton over the field of rational numbers. We give a minimisation algorithm that runs in polynomial time assuming unit-cost arithmetic. We also show that a…

Formal Languages and Automata Theory · Computer Science 2019-03-14 Stefan Kiefer , Ines Marusic , James Worrell

We show that a genuine Parrondo paradox can emerge in two-state quantum walks without resorting to experimentally intricate high-dimensional coins. To achieve such goal we employ a time-dependent coin operator without breaking the…

Quantum Physics · Physics 2020-10-28 Marcelo A. Pires , Sílvio M. Duarte Queirós

In this paper we explore the power of AM for the case that verifiers are {\em two-way finite automata with quantum and classical states} (2QCFA)--introduced by Ambainis and Watrous in 2002--and the communications are classical. It is of…

Computational Complexity · Computer Science 2015-05-05 Shenggen Zheng , Daowen Qiu , Jozef Gruska

A long sequence of tosses of a classical coin produces an apparently random bit string, but classical randomness is an illusion: the algorithmic information content of a classically-generated bit string lies almost entirely in the…

Quantum Physics · Physics 2007-05-23 Ulvi Yurtsever

A fruitful way of obtaining meaningful, possibly concrete, algorithmically random numbers is to consider a potential behaviour of a Turing machine and its probability with respect to a measure (or semi-measure) on the input space of binary…

Computational Complexity · Computer Science 2017-06-13 George Barmpalias , Douglas Cenzer , Christopher P. Porter

Coin-flipping is a fundamental cryptographic task where a spatially separated Alice and Bob wish to generate a fair coin-flip over a communication channel. It is known that ideal coin-flipping is impossible in both classical and quantum…

Quantum Physics · Physics 2020-10-28 Jamie Sikora , John H. Selby

In this paper we present a deterministic polynomial time algorithm for testing if a symbolic matrix in non-commuting variables over $\mathbb{Q}$ is invertible or not. The analogous question for commuting variables is the celebrated…

Computational Complexity · Computer Science 2019-01-25 Ankit Garg , Leonid Gurvits , Rafael Oliveira , Avi Wigderson

The field of quantum algorithms is vibrant. Still, there is currently a lack of programming languages for describing quantum computation on a practical scale, i.e., not just at the level of toy problems. We address this issue by introducing…

Programming Languages · Computer Science 2013-07-08 Alexander S. Green , Peter LeFanu Lumsdaine , Neil J. Ross , Peter Selinger , Benoît Valiron

We prove that quantum Turing machines are strictly superior to probabilistic Turing machines in function computation for any space bound $ o(\log(n)) $.

Computational Complexity · Computer Science 2010-09-17 A. C. Cem Say , Abuzer Yakaryilmaz

The present paper presents and proves a proposition concerning the time complexity of finite languages. It is shown herein, that for any finite language (a language for which the set of words composing it is finite) there is a Turing…

Computational Complexity · Computer Science 2007-05-23 Mircea Alexandru Popescu Moscu

Acknowledging that large language models have learned to use language can open doors to breakthrough language science. Achieving these breakthroughs may require abandoning some long-held ideas about how language knowledge is evaluated and…

Computation and Language · Computer Science 2025-12-16 Gary Lupyan

We construct a hierarchy of regular languages such that the current language in the hierarchy can be accepted by 1-way quantum finite automata with a probability smaller than the corresponding probability for the preceding language in the…

Quantum Physics · Physics 2007-05-23 Andris Ambainis , Richard Bonner , Rusins Freivalds , Arnolds Kikusts

We show that one-way quantum one-counter automaton with zero-error is more powerful than its probabilistic counterpart on promise problems. Then, we obtain a similar separation result between Las Vegas one-way probabilistic one-counter…

Formal Languages and Automata Theory · Computer Science 2023-06-22 Masaki Nakanishi , Abuzer Yakaryılmaz , Aida Gainutdinova

In this work we initiate the question of whether quantum devices can provide us with an almost perfect source of classical randomness, and more generally, suffice for classical cryptographic tasks, such as encryption. Indeed, it is well…

Quantum Physics · Physics 2007-05-23 Yevgeniy Dodis , Renato Renner

We show that the algorithmic complexity of any classical algorithm written in a Turing-complete programming language polynomially bounds the number of quantum bits that are required to run and even symbolically execute the algorithm on a…

Programming Languages · Computer Science 2022-11-08 Christoph M. Kirsch , Stefanie Muroya Lei

Quantum computing offers advantages over classical computation, yet the precise features that set the two apart remain unclear. In the standard quantum circuit model, adding a 1-qubit basis-changing gate -- commonly chosen to be the…

Quantum Physics · Physics 2025-11-26 Wang Fang , Chris Heunen , Robin Kaarsgaard

Large language models (LLMs) exhibit failure modes on seemingly trivial tasks. We propose a formalisation of LLM interaction using a deterministic multi-tape Turing machine, where each tape represents a distinct component: input characters,…

Computation and Language · Computer Science 2026-02-20 Magnus Boman

Quantum computing promises the ability to compute properties of quantum systems exponentially faster than classical computers. Quantum advantage is achieved when a practical problem is solved more efficiently on a quantum computer than on a…

Quantum Physics · Physics 2025-12-03 William A. Simon , Peter J. Love

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