Concise representations of reversible automata

We present two concise representations of reversible automata. Both representations have a size which is comparable with the size of the minimum equivalent deterministic automaton and can be exponentially smaller than the size of the explicit representations of corresponding reversible automata. Using those representations it is possible to simulate the computations of reversible automata without explicitly writing down their complete descriptions

Weakly and strongly irreversible regular languages

Finite automata whose computations can be reversed, at any point, by knowing the last k symbols read from the input, for a fixed k, are considered. These devices and their accepted languages are called k-reversible automata and k-reversible languages, respectively. The existence of k-reversible languages which are not (k-1)-reversible is known, for each k > 1. This gives an infinite hierarchy of weakly irreversible languages, i.e., languages which are k-reversible for some k. Conditions characterizing the class of k-reversible languages, for each fixed k, and the class of weakly irreversible languages are obtained. From these conditions, a procedure that given a finite automaton decides if the accepted language is weakly or strongly (i.e., not weakly) irreversible is described. Furthermore, a construction which allows to transform any finite automaton which is not k-reversible, but which accepts a k-reversible language, into an equivalent k-reversible finite automaton, is presented

Reversible Computation: Extending Horizons of Computing

This open access State-of-the-Art Survey presents the main recent scientific outcomes in the area of reversible computation, focusing on those that have emerged during COST Action IC1405 "Reversible Computation - Extending Horizons of Computing", a European research network that operated from May 2015 to April 2019. Reversible computation is a new paradigm that extends the traditional forwards-only mode of computation with the ability to execute in reverse, so that computation can run backwards as easily and naturally as forwards. It aims to deliver novel computing devices and software, and to enhance existing systems by equipping them with reversibility. There are many potential applications of reversible computation, including languages and software tools for reliable and recovery-oriented distributed systems and revolutionary reversible logic gates and circuits, but they can only be realized and have lasting effect if conceptual and firm theoretical foundations are established first

Reversible Computation: Extending Horizons of Computing

This open access State-of-the-Art Survey presents the main recent scientific outcomes in the area of reversible computation, focusing on those that have emerged during COST Action IC1405 "Reversible Computation - Extending Horizons of Computing", a European research network that operated from May 2015 to April 2019. Reversible computation is a new paradigm that extends the traditional forwards-only mode of computation with the ability to execute in reverse, so that computation can run backwards as easily and naturally as forwards. It aims to deliver novel computing devices and software, and to enhance existing systems by equipping them with reversibility. There are many potential applications of reversible computation, including languages and software tools for reliable and recovery-oriented distributed systems and revolutionary reversible logic gates and circuits, but they can only be realized and have lasting effect if conceptual and firm theoretical foundations are established first

Concise Representations of Reversible Automata

In this paper, we present two concise representations of reversible automata. Both representations have a size comparable to the size of the minimum equivalent deterministic automaton and can be exponentially smaller than the size of the explicit representations of corresponding reversible automata. Using these representations it is possible to simulate the computations of reversible automata without explicitly writing down their complete descriptions

Descriptional Complexity of Formal Systems

The proceedings contain 24 papers. The special focus in this conference is on Descriptional Complexity of Formal Systems. The topics include: Sensing as a complexity measure; avoiding overlaps in pictures; on the degree of nondeterminism of tree adjoining languages and head grammar languages; on the average complexity of strong star normal form; most complex non-returning regular languages; uncountable realtime probabilistic classes; a parametrized analysis of algorithms on hierarchical graphs; graph-controlled insertion-deletion systems generating language classes beyond linearity; computational completeness of networks of evolutionary processors with elementary polarizations and a small number of processors; self-attraction removal from oritatami systems; one-time nondeterministic computations; branching measures and nearly acyclic NFAS; a pumping lemma for ordered restarting automata; concise representations of reversible automata; reset complexity of ideal languages over a binary alphabet; state complexity of suffix distance and the quotient operation on input driven pushdown automata