Automatic functions, linear time and learning

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 notions permit full learnability for learning in the limit of aut...

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Main Authors: John Case, Sanjay Jain, Frank Stephan
Format: Article
Language:English
Published: Logical Methods in Computer Science e.V. 2013-09-01
Series:Logical Methods in Computer Science
Subjects:
Online Access:https://lmcs.episciences.org/734/pdf
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author John Case
Sanjay Jain
Frank Stephan
Frank Stephan
author_facet John Case
Sanjay Jain
Frank Stephan
Frank Stephan
author_sort John Case
collection DOAJ
description 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 notions permit full learnability for learning in the limit of automatic classes (families of languages which are uniformly recognised by a finite automaton). In particular it is shown that a function is automatic iff there is a one-tape Turing machine with a left end which computes the function in linear time where the input before the computation and the output after the computation both start at the left end. It is known that learners realised as automatic update functions are restrictive for learning. In the present work it is shown that one can overcome the problem by providing work tapes additional to a resource-bounded base tape while keeping the update-time to be linear in the length of the largest datum seen so far. In this model, one additional such work tape provides additional learning power over the automatic learner model and two additional work tapes give full learning power. Furthermore, one can also consider additional queues or additional stacks in place of additional work tapes and for these devices, one queue or two stacks are sufficient for full learning power while one stack is insufficient.
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spelling doaj.art-ec8ec2f1bca54bf2bddd609da4a8de022024-03-08T09:29:28ZengLogical Methods in Computer Science e.V.Logical Methods in Computer Science1860-59742013-09-01Volume 9, Issue 310.2168/LMCS-9(3:19)2013734Automatic functions, linear time and learningJohn CaseSanjay JainFrank Stephanhttps://orcid.org/0000-0001-9152-1706Frank Stephanhttps://orcid.org/0000-0001-9152-1706The 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 notions permit full learnability for learning in the limit of automatic classes (families of languages which are uniformly recognised by a finite automaton). In particular it is shown that a function is automatic iff there is a one-tape Turing machine with a left end which computes the function in linear time where the input before the computation and the output after the computation both start at the left end. It is known that learners realised as automatic update functions are restrictive for learning. In the present work it is shown that one can overcome the problem by providing work tapes additional to a resource-bounded base tape while keeping the update-time to be linear in the length of the largest datum seen so far. In this model, one additional such work tape provides additional learning power over the automatic learner model and two additional work tapes give full learning power. Furthermore, one can also consider additional queues or additional stacks in place of additional work tapes and for these devices, one queue or two stacks are sufficient for full learning power while one stack is insufficient.https://lmcs.episciences.org/734/pdfcomputer science - formal languages and automata theory
spellingShingle John Case
Sanjay Jain
Frank Stephan
Frank Stephan
Automatic functions, linear time and learning
Logical Methods in Computer Science
computer science - formal languages and automata theory
title Automatic functions, linear time and learning
title_full Automatic functions, linear time and learning
title_fullStr Automatic functions, linear time and learning
title_full_unstemmed Automatic functions, linear time and learning
title_short Automatic functions, linear time and learning
title_sort automatic functions linear time and learning
topic computer science - formal languages and automata theory
url https://lmcs.episciences.org/734/pdf
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