We address the problem of tight XML schemas and propose regular tree automata to model XML data. We show that the tree automata model is more powerful that the XML DTDs and is closed under main algebraic operations. We introduce the XML query algebra based the tree automata model, and discuss the query optimization and query pruning techniques. Finally, we show the conversion of tree automata s...

There are two kinds of bisimulation, namely crisp and fuzzy, between fuzzy structures such as automata, labeled transition systems, Kripke models interpretations in description logics. Fuzzy bisimulations automata over a complete residuated lattice have been introduced by ?iri? et al. 2012. Logical characterizations (respectively, logics) the [0,1] with Gödel t-norm provided Fan 2015 Nguyen 202...

In this paper intuitionistic fuzzy pushdown automata, acceptance by empty stack and acceptance by final states and their equivalence is proved. It follows that intuitionistic fuzzy pushdown automata with empty stack and IFPDAs are equivalent. We propose the notions of intuitionistic fuzzy context-free grammars (IFCFGs), intuitionistic fuzzy languages generated by IFCFGs. Additionally, we introd...

in this note first by considering the notion of general fuzzy automata (for simplicity gfa), we define the notions of direct product, restricted direct product and join of two gfa. also, we introduce some operations on (fuzzy) sets and then prove some related theorems. finally we construct the general fuzzy recognizers and recognizable sets and give the notion of (trim) reversal of a given gfa....

We address the problem of computing simulation relations over tree automata. In particular, we consider downward and upward simulations on tree automata, which are, loosely speaking, analogous to forward and backward relations over word automata. We provide simple and efficient algorithms for computing these relations based on a reduction to the problem of computing simulations on labelled tran...

Equational tree automata provide a powerful tree language framework that facilitates to recognize congruence closures of tree languages. In the paper we show the emptiness problem for AC-tree automata and the intersection-emptiness problem for regular AC-tree automata, each of which was open in our previous work [20], are decidable, by a straightforward reduction to the reachability problem for...

Tree pattern matching (tpm) algorithms play an important role in practical applications such as compilers and XML document validation. Many tpm algorithms based on tree automata have appeared in the literature. For reasons of efficiency, these automata are preferably deterministic. Deterministic root-to-frontier tree automata (drftas) are less powerful than nondeterministic ones, and no root-to...