Tree-adjoining grammar

About: Tree-adjoining grammar is a research topic. Over the lifetime, 2491 publications have been published within this topic receiving 57813 citations.

Optimal $k$-arization of Synchronous Tree-Adjoining Grammar

Abstract: Synchronous Tree-Adjoining Grammar (STAG) is a promising formalism for syntaxaware machine translation and simultaneous computation of natural-language syntax and semantics. Current research in both of these areas is actively pursuing its incorporation. However, STAG parsing is known to be NP-hard due to the potential for intertwined correspondences between the linked nonterminal symbols in the elementary structures. Given a particular grammar, the polynomial degree of efficient STAG parsing algorithms depends directly on the rank of the grammar: the maximum number of correspondences that appear within a single elementary structure. In this paper we present a compile-time algorithm for transforming a STAG into a strongly-equivalent STAG that optimally minimizes the rank, k, across the grammar. The algorithm performs inO(|G| +|Y|·L 3 ) time where LG is the maximum number of links in any single synchronous tree pair in the grammar and Y is the set of synchronous tree pairs ofG.

Semantics of visual languages

Abstract: The general syntactical model of Relation Grammars has been introduced to describe any kind of graphical languages. This paper describes a technique for the semantic analysis of visual languages specified by relation grammars. The technique is based on the definition of Attribute Relation Grammars (ARG), which are an extension of attribute context-free grammars to the case of non-linear grammars. We study the static properties of an ARG under which each sentence can be translated with a cost linear in the size of the sentence.

Parallel communicating grammar systems with terminal transmission

Abstract: We introduce a new variant of PC grammar systems, called PC grammar systems with terminal transmission, PCGSTT for short. We show that right-linear centralized PCGSTT have nice formal language theoretic properties: they are closed under gsm mappings (in particular, under intersection with regular sets and under homomorphisms) and union; a slight variant is, in addition, closed under concatenation and star; their power lies between that of n-parallel grammars introduced by Wood and that of matrix languages of index n, and their relation to equal matrix grammars of degree n is discussed. We show that membership for these language classes is complete for NL. In a second part of the paper, we discuss questions concerning grammatical inference of these systems. More precisely, we show that PCGSTT whose component grammars are terminal distinguishable right-linear, a notion introduced by Radhakrishnan and Nagaraja in [33,34], are identifiable in the limit if certain data communication information is supplied in addition.

Iterative type inference with attribute grammars

Abstract: Type inference is the process of constructing a typing derivation while gradually discovering type information. During this process, inference algorithms typically make subtle decisions based on the derivation constructed so far.Because a typing derivation is a decorated tree we aim to use attribute grammars as the main implementation tool. Unfortunately, we can neither express iteration, nor express decisions based on intermediate derivations in such grammars.We present the language ruler-front, a conservative extension to ordered attribute grammars, that deals with the aforementioned problems. We show why this extension is suitable for the description of constraint-based inference algorithms.

Valence Grammars with Target Sets

Abstract: We discuss an extension of valence grammars, where the value of a valid derivation is allowed to be an element of a given target set. We discuss closure properties of language families generated by such grammars. Moreover, we investigate the generative power of valence grammars with target sets over the groups Z k , over the monoids N k and over finite monoids. This way, we also prove a conjecture due to M. Jantzen stating that unordered vector languages can be characterized by grammars controlled by permutations of regular languages. Furthermore, we show that matrix languages are characterized by valence grammars with target sets over (arbitrary) finite monoids.