Clearing and subword-clearing restarting automata are linguistically motivated models of automata. We investigate the problem of grammatical inference for such automata based on the given set of positive and negative samples. We show that it is possible to identify these models in the limit. In this way we can learn a large class of languages. On the other hand, we prove that the task of nding a clearing restarting automaton consistent with a given set of positive and negative samples is NP-hard, provided that we impose an upper bound on the width of its instructions.

/pdf/clearing-restarting-automata-and-grammatical-inference-29g4du3ef3.pdf

Clearing Restarting Automata and Grammatical Inference

The restarting automaton, introduced by Jancar et al in 1995, is motivated by the so-called 'analysis by reduction,' a technique from linguistics. By now there are many different models of restarting automata, and their investigation has proved very fruitful in that they offer an opportunity to study the influence of various kinds of resources on their expressive power. Here a survey on the various models and their properties is given, their relationships to the language classes of the Chomsky hierarchy are described, and some open problems are presented.

Restarting automata and their relations to the Chomsky hierarchy

In the literature various types of restarting automata have been studied that are based
 on contextual rewriting. A word w is accepted by such an automaton if,
 starting from the initial configuration that corresponds to input w , the
 word w is reduced to the empty word by a finite number of applications of
 these contextual rewritings. This approach is reminiscent of the notion of McNaughton
 families of languages. Here we put the aforementioned types of restarting automata into
 the context of McNaughton families of languages, relating the classes of languages
 accepted by these automata in particular to the class GCSL of growing context-sensitive
 languages and to the class CRL of Church–Rosser languages.

/pdf/on-the-classes-of-languages-accepted-by-limited-context-55oqk7fb01.pdf

On the classes of languages accepted by limited context restarting automata

First, we show that universality and other properties of general jumping finite automata are undecidable, which answers questions asked by Meduna and Zemek in 2012 [12]. Second, we close a study started by Cerno and Mraz in 2010 [3] by proving that a clearing restarting automaton using contexts of length two can accept a binary non-context-free language.

Two Results on Discontinuous Input Processing.

Limited Context Restarting Automata and McNaughton Families of Languages.

Restarting automata were introduced as a model for analysis by reduction, which is a linguistically motivated method for checking correctness of a sentence. We propose a new restricted version of restarting automata called clearing restarting automata with a very simple definition but simultaneously with interesting properties with respect to their possible applications. The new model can be learned very efficiently from positive examples and its stronger version can be used to learn effectively a large class of languages. We relate the class of languages recognized by clearing restarting automata to the Chomsky hierarchy.

Clearing Restarting Automata

Δ-clearing restarting automata represent a new restricted model of restarting automata which, based on a limited context, can either delete a substring of the current content of its tape or replace a substring by a special auxiliary symbol Δ, which cannot be overwritten anymore, but it can be deleted later. The main result of this paper consists in proving that besides their limited operations, Δ-clearing restarting automata recognize all context-free languages.

Peter Černo

Papers

Clearing Restarting Automata

Clearing Restarting Automata and Grammatical Inference

On the classes of languages accepted by limited context restarting automata

Limited Context Restarting Automata and McNaughton Families of Languages.

Δ-Clearing Restarting Automata and $\makebox{\sf CFL} $