In this paper, our focus of attention is the proper propagationof fuzzy degrees in determinization of $Nondeterministic$ $Fuzzy$$Finite$ $Tree$ $Automata$ (NFFTA). Initially, two determinizationmethods are introduced which have some limitations (one inbehavior preserving and other in type of fuzzy operations). Inorder to eliminate these limitations and increasing theefficiency of FFTA, we defin...

Pushdown automata are devices that can efficiently represent context-free languages, have natural weighted versions, and combine naturally with finite automata. We describe a pushdown transducer extension to OpenFst, a weighted finite-state transducer library. We present several weighted pushdown algorithms, some with clear finite-state analogues, describe their library usage and give some appl...

We define simple-regular expressions and languages. Simple-regular languages provide a necessary condition for a language to be outfix-free. We design algorithms that compute simple-regular languages from finite-state automata. Furthermore, we investigate the complexity blowup from a given finite-state automaton to its simple-regular language automaton and show that there is an exponential blow...

One of the properties of the Kondacs-Watrous model of quantum finite automata (QFA) is that the probability of the correct answer for a QFA cannot be amplified arbitrarily. In this paper, we determine the maximum probabilities achieved by QFAs for several languages. In particular, we show that any language that is not recognized by an RFA (reversible finite automaton) can be recognized by a QFA...

Urn automata are a new class of automata consisting of an input tape, a finite-state controller, and an urn containing tokens with a finite set of colors, where the finite-state controller can sample and replace tokens in the urn but cannot control which tokens it receives. We consider the computational power of urn automata, showing that an urn automaton with O(f(n)) tokens can, with high prob...

We introduce an affine generalization of counter automata, and analyze their ability as well as affine finite automata. Our contributions are as follows. We show that there is a language that can be recognized by exact realtime affine counter automata but by neither 1-way deterministic pushdown automata nor realtime deterministic k-counter automata. We also show that a certain promise problem, ...

Quantum finite automata (QFAs) are quantum counterparts of the usual finite automata. 1way QFAs recognize the same languages as conventional finite automata but can be exponentially more space-efficient. In this talk, we describe the main results about quantum finite automata and some possible areas for future work. In particular, we will discuss: • the languages for which QFAs can be smaller t...

Bertoni et al. introduced in Lect. Notes Comput. Sci. 2710 (2003) 1–20 a new model of 1-way quantum finite automaton (1qfa) called 1qfa with control language (1qfc). This model, whose recognizing power is exactly the class of regular languages, generalizes main models of 1qfa’s proposed in the literature. Here, we investigate some properties of 1qfc’s. In particular, we provide algorithms for c...

Determining the minimum number of states required by a finite automaton to separate a given pair of different words is an important problem. In this paper, we consider this problem for quantum automata (QFAs). We show that 2-state QFAs can separate any pair of words in nondeterministic acceptance mode and conjecture that they can separate any pair also with zero-error. Then, we focus on (a more...