background: rna molecules play many important regulatory, catalytic and structuralroles in the cell, and rna secondary structure prediction with pseudoknots is one themost important problems in biology. an rna pseudoknot is an element of the rna secondary structure in which bases of a single-stranded loop pair with complementary basesoutside the loop. modeling these nested structures (pseudokno...

We describe a workbench (XTAG) for the development of tree-adjoining grammars and their parsers, and discuss some issues that arise in the design of the graphical interface. Contrary to string rewriting grammars generating trees, the elementary objects manipulated by a tree-adjoining grammar are extended trees (i.e. trees of depth one or more) which capture syntactic information of lexical item...

The tree languages of tree-adjoining grammars are precisely those of linear monadic context-free tree grammars. Unlike the original proof, we present a direct transformation of a tree-adjoining grammar into an equivalent linear monadic context-free tree grammar.

Recently, it was shown (KUHLMANN, SATTA: Tree-adjoining grammars are not closed under strong lexicalization. Comput. Linguist., 2012) that finitely ambiguous tree adjoining grammars cannot be transformed into a normal form (preserving the generated tree language), in which each production contains a lexical symbol. A more powerful model, the simple context-free tree grammar, admits such a norma...

Strong lexicalization is the process of turning a grammar generating trees into an equivalent one, in which all rules contain a terminal leaf. It is known that tree adjoining grammars cannot be strongly lexicalized, whereas the more powerful simple context-free tree grammars can. It is demonstrated that multiple simple context-free tree grammars are as expressive as multi-component tree adjoini...

A lexicalized tree-adjoining grammar is a tree-adjoining grammar where each elementary tree contains some overt lexical item. Such grammars are being used to give lexical accounts of syntactic phenomena, where an elementary tree defines the domain of locality of the syntactic and semantic dependencies of its lexical items. It has been claimed in the literature that for every tree-adjoining gram...

In this paper we introduce a new mildly context sensitive formalism called Multi-Component Tree Insertion Grammar. This formalism is a generalization of Tree Insertion Grammars in the same sense that Multi-Component Tree Adjoining Grammars is a generalization of Tree Adjoining Grammars. We show that this class of grammatical formalisms is equivalent to Multi-Component Tree Adjoining Grammars, a...