Tree algebras and varieties of tree languages
نویسندگان
چکیده
منابع مشابه
Tree algebras and varieties of tree languages
We consider several aspects of Wilke’s [T. Wilke, An algebraic characterization of frontier testable tree languages, Theoret. Comput. Sci. 154 (1996) 85–106] tree algebra formalism for representing binary labelled trees and compare it with approaches that represent trees as terms in the traditional way. A convergent term rewriting system yields normal form representations of binary trees and co...
متن کاملGeneral Varieties of Tree Languages
We consider varieties of tree languages which are not restricted to a fixed ranked alphabet, varieties of finite algebras that contain algebras of all finite types, and a matching notion of varieties of congruences. A variety theorem that yields isomorphisms between the lattices formed by these three types of varieties is proved. To achieve this, some basic universal algebra is suitably general...
متن کاملVarieties of Unranked Tree Languages
We study varieties that contain unranked tree languages over all alphabets. Trees are labeled with symbols from two alphabets, an unranked operator alphabet and an alphabet used for leaves only. Syntactic algebras of unranked tree languages are defined similarly as for ranked tree languages, and an unranked tree language is shown to be recognizable iff its syntactic algebra is regular, i.e., a ...
متن کاملOn the Solidity of General Varieties of Tree Languages
For a class of hypersubstitutions K, we define the K-solidity of general varieties of tree languages (GVTLs) that contain tree languages over all alphabets, general varieties of finite algebras (GVFAs), and general varieties of finite congruences (GVFCs). We show that if K is a so-called category of substitutions, a GVTL is K-solid exactly in case the corresponding GVFA, or the corresponding GV...
متن کاملAuthor: Saeed Salehi (Saeed @ Math.Net) Title: Varieties of Tree Languages
Trees are among the most fundamental and ubiquitous structures in mathematics. Tree languages and automata on trees have been studied extensively since the 1960s from both a purely mathematical and application point of view. When trees are defined as terms, universal algebra becomes directly applicable to tree automata and, on the other hand, the theory of tree automata suggests new notions and...
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ژورنال
عنوان ژورنال: Theoretical Computer Science
سال: 2007
ISSN: 0304-3975
DOI: 10.1016/j.tcs.2007.02.006