Order-Preserving DAG Grammars (OPDGs) is a subclass of Hyper-Edge Replacement Grammars that can be parsed in polynomial time. Their associated class of languages is known as Ordered DAG Languages, and the graphs they generate are characterised by being acyclic, rooted, and having a natural order on their nodes. OPDGs are useful in natural-language processing to model abstract meaning representa...

We present a learning algorithm for regular languages that unifies three existing ones for the settings of minimally adequate teacher learning, learning from membership queries and positive data, and learning from positive and negative data, respectively. We choose these three algorithms as an example to back up the conjecture that the learning process of every algorithm for the class of regula...

Families of dfas (fdfas) provide an alternative formalism for recognizing ω-regular languages. The motivation for introducing them was a desired correlation between the automaton states and right congruence relations, in a manner similar to the Myhill-Nerode theorem for regular languages. This correlation is beneficial for learning algorithms, and indeed it was recently shown that ω-regular lan...

In this thesis we will introduce topological automata and the topological entropy of a topological automaton, which is the topological entropy of the dynamical system contained in the automaton. We will use these notions to define a measure of complexity for formal languages. We assign to every language the topological entropy of the unique minimal topological automaton accepting it. We contrib...

The purpose of this work is to introduce and study the concept of minimal deterministic automaton with IF-outputs which realizes the given IF-language. Among two methods for construction of such automaton presented here, one is based on Myhill-Nerode’s theory while the other is based on derivatives of the given IF-language. Meanwhile, the categories of deterministic automata with IF-outputs and...

In this paper we consider when a linear functional on a bialgebra is realized by the action of the bialgebra on a finite object. This depends on whether the action of the bialgebra on the functional is finite. We consider two specific cases: the Myhill–Nerode Theorem, which gives a condition for a language to be accepted by a finite automaton, and Fliess’ Theorem, which gives a condition for fo...

We formally verify translations from two-way automata to one-way automata based on results from the literature. Following Vardi, we obtain a simple reduction from nondeterministic two-way automata to one-way automata that leads to a doubly-exponential increase in the number of states. By adapting the work of Shepherdson and Vardi, we obtain a singlyexponential translation from nondeterministic ...

In order to model concurrency, we extend automata theory from the usual word languages (sets of labelled linear orders) to sets of labelled series-parallel posets | or, equivalently, to sets of terms in an algebra with two product operations: sequential and parallel. We rst consider languages of posets having bounded width, and characterize them using depth-nilpotent algebras. Next we introduce...

It is well known that finite square matrices over a Kleene algebra again form a Kleene algebra. This is also true for infinite matrices under suitable restrictions. One can use this fact to solve certain infinite systems of inequalities over a Kleene algebra. Automatic systems are a special class of infinite systems that can be viewed as infinite-state automata. Automatic systems can be collaps...