STACS 2004: STACS 2004 pp 440-451

Definability and Regularity in Automatic Structures

• Sasha Rubin
• Frank Stephan
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 2996)

Abstract

An automatic structure $$\mathcal{A}$$ is one whose domain A and atomic relations are finite automaton (FA) recognisable. A structure isomorphic to $$\mathcal{A}$$ is called automatically presentable. Suppose R is an FA recognisable relation on A. This paper concerns questions of the following type. For which automatic presentations of $$\mathcal{A}$$ is (the image of) R also FA recognisable? To this end we say that a relation R is intrinsically regular in a structure $$\mathcal{A}$$ if it is FA recognisable in every automatic presentation of the structure. For example, in every automatic structure all relations definable in first order logic are intrinsically regular. We characterise the intrinsically regular relations of some automatic fragments of arithmetic in the first order logic extended with quantifiers ∃  ∞  interpreted as ‘there exists infinitely many’, and ∃ (i) interpreted as ‘there exists a multiple of i many’.

Keywords

Turing Machine Order Logic Finite Automaton Unary Relation Reachability Problem
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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