27 research outputs found
Poboljšani algoritmi za determinizaciju fazi i težinskih automata
Determinization algorithms are methods that calculate complete deterministic
fuzzy (weighted) automaton that is language equivalent to the input fuzzy
(weighted) automaton, and they have found application in numerous fields,
including lexicographic analysis, analysis of regular expressions, automatic
speech recognition, pattern recognition in artificial intelligence, etc.
Especially important class of determinization algorithms are canonization
algorithms, which produce minimal complete deterministic fuzzy (weighted)
automaton equivalent to the input fuzzy (weighted) automaton. The aim of
this dissertation is the development of determinization algorithms based on
the concept of factorizations, as well as computing and merging of the
indistinguishable states of fuzzy (weighted) automaton under construction. At
the same time, computing and merging of the indistinguishable states is done
by right and left invariant fuzzy relations in the case of fuzzy automata, as
well as by right and left invariant Boolean matrices in the case of weighted
automata. We apply the partition refinement technique to obtain improved
algorithms for computing the greatest right and left invariant Boolean
equivalence and quasi – order matrices. In the end, we consider ways to
compute the greatest right and left invariant fuzzy equivalences and fuzzy
quasi – orders when the algorithms for their computation, based on the
partition refinement technique, are unable to stop in a finite number of steps
Weighted Tree Automata -- May it be a little more?
This is a book on weighted tree automata. We present the basic definitions
and some of the important results in a coherent form with full proofs. The
concept of weighted tree automata is part of Automata Theory and it touches the
area of Universal Algebra. It originated from two sources: weighted string
automata and finite-state tree automata
Generators and Bases for Monadic Closures
It is well-known that every regular language admits a unique minimal deterministic acceptor. Establishing an analogous result for non-deterministic acceptors is significantly more difficult, but nonetheless of great practical importance. To tackle this issue, a number of sub-classes of nondeterministic automata have been identified, all admitting canonical minimal representatives. In previous work, we have shown that such representatives can be recovered categorically in two steps. First, one constructs the minimal bialgebra accepting a given regular language, by closing the minimal coalgebra with additional algebraic structure over a monad. Second, one identifies canonical generators for the algebraic part of the bialgebra, to derive an equivalent coalgebra with side effects in a monad. In this paper, we further develop the general theory underlying these two steps. On the one hand, we show that deriving a minimal bialgebra from a minimal coalgebra can be realized by applying a monad on an appropriate category of subobjects. On the other hand, we explore the abstract theory of generators and bases for algebras over a monad
Generators and Bases for Monadic Closures
It is well-known that every regular language admits a unique minimal deterministic acceptor. Establishing an analogous result for non-deterministic acceptors is significantly more difficult, but nonetheless of great practical importance. To tackle this issue, a number of sub-classes of non-deterministic automata have been identified, all admitting canonical minimal representatives. In previous work, we have shown that such representatives can be recovered categorically in two steps. First, one constructs the minimal bialgebra accepting a given regular language, by closing the minimal coalgebra with additional algebraic structure over a monad. Second, one identifies canonical generators for the algebraic part of the bialgebra, to derive an equivalent coalgebra with side effects in a monad. In this paper, we further develop the general theory underlying these two steps. On the one hand, we show that deriving a minimal bialgebra from a minimal coalgebra can be realized by applying a monad on an appropriate category of subobjects. On the other hand, we explore the abstract theory of generators and bases for algebras over a monad
Algebraic decoder specification: coupling formal-language theory and statistical machine translation: Algebraic decoder specification: coupling formal-language theory and statistical machine translation
The specification of a decoder, i.e., a program that translates sentences from one natural language into another, is an intricate process, driven by the application and lacking a canonical methodology. The practical nature of decoder development inhibits the transfer of knowledge between theory and application, which is unfortunate because many contemporary decoders are in fact related to formal-language theory. This thesis proposes an algebraic framework where a decoder is specified by an expression built from a fixed set of operations. As yet, this framework accommodates contemporary syntax-based decoders, it spans two levels of abstraction, and, primarily, it encourages mutual stimulation between the theory of weighted tree automata and the application