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Inspired by multi-head finite automata and Watson-Crick automata in this paper, we introduce new structure namely multi-head Watson-Crick automata where we replace the single tape of multi-head finite automaton by a DNA double strand. The…

Formal Languages and Automata Theory · Computer Science 2015-12-10 Kingshuk Chatterjee , Kumar Sankar Ray

The present work determines the exact nature of {\em linear time computable} notions which characterise automatic functions (those whose graphs are recognised by a finite automaton). The paper also determines which type of linear time…

Formal Languages and Automata Theory · Computer Science 2018-04-19 John Case , Sanjay Jain , Samuel Seah , Frank Stephan

Recent studies show that the attention heads in Transformer are not equal. We relate this phenomenon to the imbalance training of multi-head attention and the model dependence on specific heads. To tackle this problem, we propose a simple…

Computation and Language · Computer Science 2022-09-01 Zewei Sun , Shujian Huang , Xin-Yu Dai , Jiajun Chen

In various models of one-way pushdown automata, the explicit use of two designated endmarkers on a read-once input tape has proven to be extremely useful for making a conscious, final decision on the acceptance/rejection of each input word…

Formal Languages and Automata Theory · Computer Science 2025-11-11 Tomoyuki Yamakami

We describe various computational models based initially, but not exclusively, on that of the Turing machine, that are generalized to allow for transfinitely many computational steps. Variants of such machines are considered that have…

Logic · Mathematics 2014-09-19 Philip Welch

A popular approach for predicting the future of dynamical systems involves mapping them into a lower-dimensional "latent space" where prediction is easier. We show that the information-theoretically optimal approach uses different mappings…

Data Analysis, Statistics and Probability · Physics 2019-02-22 Max Tegmark

Determining an appropriate number of attention heads on one hand and the number of transformer-encoders, on the other hand, is an important choice for Computer Vision (CV) tasks using the Transformer architecture. Computing experiments…

Computer Vision and Pattern Recognition · Computer Science 2022-11-01 Tomas Hrycej , Bernhard Bermeitinger , Siegfried Handschuh

Transformer has been successfully applied to many natural language processing tasks. However, for textual sequence matching, simple matching between the representation of a pair of sequences might bring in unnecessary noise. In this paper,…

Computation and Language · Computer Science 2020-01-22 Shuohang Wang , Yunshi Lan , Yi Tay , Jing Jiang , Jingjing Liu

We show that 2-tag systems efficiently simulate Turing machines. As a corollary we find that the small universal Turing machines of Rogozhin, Minsky and others simulate Turing machines in polynomial time. This is an exponential improvement…

Computational Complexity · Computer Science 2016-11-17 Damien Woods , Turlough Neary

We investigate computational resources used by Turing machines (TMs) and alternating Turing machines (ATMs) to accept languages generated by coordinated table selective substitution systems with two components. We prove that the class of…

Formal Languages and Automata Theory · Computer Science 2022-02-08 Liliana Cojocaru

We discuss the power and limitation of various "advice," when it is given particularly to weak computational models of one-tape linear-time Turing machines and one-way finite (state) automata. Of various advice types, we consider…

Formal Languages and Automata Theory · Computer Science 2011-07-21 Tomoyuki Yamakami

Multi-head attention powers Transformer networks, the primary deep learning architecture behind the success of large language models (LLMs). Yet, the theoretical advantages of multi-head versus single-head attention, beyond mere parallel…

Machine Learning · Computer Science 2025-11-11 Haitz Sáez de Ocáriz Borde

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

For any fixed $k$, a remarkably simple single-tape Turing machine can simulate $k$ independent counters in real time. Informally, a counter is a storage unit that maintains a single integer (initially 0), incrementing it, decrementing it,…

Computational Complexity · Computer Science 2007-05-23 Joel Seiferas , Paul Vitanyi

Magnetic tapes are often considered as an outdated storage technology, yet they are still used to store huge amounts of data. Their main interests are a large capacity and a low price per gigabyte, which come at the cost of a much larger…

Distributed, Parallel, and Cluster Computing · Computer Science 2022-05-05 Valentin Honoré , Bertrand Simon , Frédéric Suter

Multi-head attention layers, as used in the Transformer neural sequence model, are a powerful alternative to RNNs for moving information across and between sequences. While training these layers is generally fast and simple, due to…

Neural and Evolutionary Computing · Computer Science 2019-11-07 Noam Shazeer

The question whether P equals NP revolves around the discrepancy between active production and mere verification by Turing machines. In this paper, we examine the analogous problem for finite transducers and automata. Every nondeterministic…

Computational Complexity · Computer Science 2021-05-03 Elisabet Burjons , Fabian Frei , Martin Raszyk

Deterministic 2-head finite automata which are machines that process an input word from both ends are analyzed for their ability to perform reversible computations. This implies that the automata are backward deterministic, enabling unique…

Formal Languages and Automata Theory · Computer Science 2025-07-22 Benedek Nagy , Walaa Yasin

We prove that a sufficiently strong parallel repetition theorem for a special case of multiplayer (multiprover) games implies super-linear lower bounds for multi-tape Turing machines with advice. To the best of our knowledge, this is the…

Computational Complexity · Computer Science 2020-11-30 Kunal Mittal , Ran Raz

We show that multiplication can be done in polynomial time on a three counter machine that receives its input as the contents of two counters. The technique is generalized to functions of two variables computable by deterministic Turing…

Computational Complexity · Computer Science 2015-01-12 Holger Petersen