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We introduce the zeta number, natural halting probability and natural complexity of a Turing machine and we relate them to Chaitin's Omega number, halting probability, and program-size complexity. A classification of Turing machines…

Computational Complexity · Computer Science 2007-05-23 Cristian S. Calude , Michael A. Stay

An algebraic representation of the Turing machines is given, where the configurations of Turing machines are represented by 4 order tensors, and the transition functions by 8 order tensors. Two types of tensor product are defined, one is to…

Computational Complexity · Computer Science 2016-07-14 Yue Liu

We show that transformer-based large language models are computationally universal when augmented with an external memory. Any deterministic language model that conditions on strings of bounded length is equivalent to a finite automaton,…

Computation and Language · Computer Science 2023-01-12 Dale Schuurmans

We present a criterion that serves as the basis for a polynomial-time algorithm to decide whether a finite set of qudit gates exponentiated by some Hamiltonians is universal. Our approach formulates universality in Lie algebraic terms and…

Quantum Physics · Physics 2026-04-30 Yinuo Xue , Qian Chen , Jing-Song Huang

In this paper we explore the power of tile self-assembly models that extend the well-studied abstract Tile Assembly Model (aTAM) by permitting tiles of shapes beyond unit squares. Our main result shows the surprising fact that any aTAM…

Data Structures and Algorithms · Computer Science 2012-12-20 Erik D. Demaine , Martin L. Demaine , Sándor P. Fekete , Matthew J. Patitz , Robert T. Schweller , Andrew Winslow , Damien Woods

A proof is given, which relies on the commutator algebra of the unitary Lie groups, that quantum gates operating on just two bits at a time are sufficient to construct a general quantum circuit. The best previous result had shown the…

Condensed Matter · Physics 2009-10-22 David P. Divincenzo

A two-way deterministic finite state automaton with one counter (2D1CA) is a fundamental computational model that has been examined in many different aspects since sixties, but we know little about its power in the case of unary languages.…

Formal Languages and Automata Theory · Computer Science 2014-07-09 Marzio De Biasi , Abuzer Yakaryilmaz

Two Turing Machines may be able to answer questions about each other that they cannot answer about themselves.

Logic in Computer Science · Computer Science 2016-10-31 Eric Hehner

Particle-style token machines are a way to interpret proofs and programs, when the latter are defined according to the principles of linear logic. In this paper, we show that token machines also make sense when the programs at hand are…

Logic in Computer Science · Computer Science 2013-11-14 Ugo Dal Lago , Margherita Zorzi

Chern-Simons topological quantum computer is a device that can be effectively described by the Chern-Simons topological quantum field theory and used for quantum computations. Quantum qudit gates of this quantum computer are represented by…

High Energy Physics - Theory · Physics 2022-02-10 Nikita Kolganov , Sergey Mironov , Andrey Morozov

Nielsen [quant-ph/0108020] showed that universal quantum computation is possible given quantum memory and the ability to perform projective measurements on up to 4-qubits. We describe an improved method that requires only 2-qubit…

Quantum Physics · Physics 2007-05-23 D. W. Leung

A remarkable new definition of a self-delimiting universal Turing machine is presented that is easy to program and runs very quickly. This provides a new foundation for algorithmic information theory. This new universal Turing machine is…

chao-dyn · Physics 2008-02-03 G. J. Chaitin

We study the paradoxical aspects of closed time-like curves and their impact on the theory of computation. After introducing the $\text{TM}_\text{CTC}$, a classical Turing machine benefiting CTCs for backward time travel, Aaronson et al.…

Computational Complexity · Computer Science 2023-01-30 Sara Babaee Khanehsar , Farzad Didehvar

We prove the STP=BQP conjecture of Freedman, Hastings and Shokrian-Zini [1], namely that the two-qubit singlet/triplet measurement is quantum computationally universal given only an initial ensemble of maximally mixed single qubits. This…

Quantum Physics · Physics 2023-11-13 Terry Rudolph , Shashank Soyuz Virmani

As one of the most intriguing intrinsic properties of quantum world, quantum superposition provokes great interests in its own generation. Oszmaniec [Phys. Rev. Lett. 116, 110403 (2016)] have proven that though a universal quantum machine…

The notion of quantum Turing machines is a basis of quantum complexity theory. We discuss a general model of multi-tape, multi-head Quantum Turing machines with multi final states that also allow tape heads to stay still.

Quantum Physics · Physics 2007-05-23 Tomoyuki Yamakami

We introduce and investigate forgetting 1-limited automata, which are single-tape Turing machines that, when visiting a cell for the first time, replace the input symbol in it by a fixed symbol, so forgetting the original contents. These…

Formal Languages and Automata Theory · Computer Science 2023-09-19 Giovanni Pighizzini , Luca Prigioniero

In this paper, we construct a strongly universal cellular automaton on the line with 11 states and the standard neighbourhood. We embed this construction into several tilings of the hyperbolic plane and of the hyperbolic 3D space giving…

Discrete Mathematics · Computer Science 2013-09-09 Maurice Margenstern

Quantum computers are unnecessary for exponentially-efficient computation or simulation if the Extended Church-Turing thesis---a foundational tenet of computer science---is correct. The thesis would be directly contradicted by a physical…

Models of computation operating over the real numbers and computing a larger class of functions compared to the class of general recursive functions invariably introduce a non-finite element of infinite information encoded in an arbitrary…

Computational Complexity · Computer Science 2010-12-20 Hector Zenil