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.

Finite automata and non-self-embedding grammars

Abstract: We consider non-self-embedding (NSE) context-free grammars as a representation of regular sets.We point out its advantages with respect to more classical representations by finite automata, in particular when considering the efficient realization of the rational operations. We give a characterization in terms of composition of regular grammars and state relationships between NSE grammars and push-down automata. Finally we show a polynomial algorithm to decide whether a context-free grammars is self-embedding or not.

Range Concatenation Grammars for Translation

Abstract: Positive and bottom-up non-erasing binary range concatenation grammars (Boullier, 1998) with at most binary predicates ((2,2)-BRCGs) is a O(|G|n6) time strict extension of inversion transduction grammars (Wu, 1997) (ITGs). It is shown that (2,2)-BRCGs induce inside-out alignments (Wu, 1997) and cross-serial discontinuous translation units (CDTUs); both phenomena can be shown to occur frequently in many hand-aligned parallel corpora. A CYK-style parsing algorithm is introduced, and induction from aligment structures is briefly discussed. Range concatenation grammars (RCG) (Boullier, 1998) mainly attracted attention in the formal language community, since they recognize exactly the polynomial time recognizable languages, but recently they have been argued to be useful for data-driven parsing too (Maier and Sogaard, 2008). Bertsch and Nederhof (2001) present the only work to our knowledge on using RCGs for translation. Both Bertsch and Nederhof (2001) and Maier and Sogaard (2008), however, only make use of so-called simple RCGs, known to be equivalent to linear context-free rewrite systems (LCFRSs) (Weir, 1988; Boullier, 1998). Our strict extension of ITGs, on the other hand, makes use of the ability to copy substrings in RCG derivations; one of the things that makes RCGs strictly more expressive than LCFRSs. Copying enables us to recognize the intersection of any two translations that we can recognize and induce the union c © 2008. Licensed under the Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported license (http://creativecommons.org/licenses/by-nc-sa/3.0/). Some rights reserved. of any two alignment structures that we can induce. Our extension of ITGs in fact introduces two things: (i) A clause may introduce any number of terminals. This enables us to induce multiword translation units. (ii) A clause may copy a substring, i.e. a clause can associate two or more nonterminals A1, . . . An with the same substring and thereby check if the substring is in the intersection of the languages of the subgrammars with start predicate names A1, . . . An. The first point is motivated by studies such as Zens and Ney (2003) and simply reflects that in order to induce multiword translation units in this kind of synchronous grammars, it is useful to be able to introduce multiple terminals simultaneously. The second point gives us a handle on context-sensitivity. It means that (2,2)-BRCGs can define translations such as {〈anbmcndm, anbmdmcn〉 | m,n ≥ 0}, i.e. a translation of cross-serial dependencies into nested ones; but it also means that (2,2)-BRCGs induce a larger class of alignment structures. In fact the set of alignment structures that can be induced is closed under union, i.e. any alignment structure can be induced. The last point is of practical interest. It is shown below that phenomena such as inside-out alignments and CDTUs, which cannot be induced by ITGs, but by (2,2)-BRCGs, occur frequently in many hand-aligned parallel corpora. 1 (2,2)-BRCGs and ITGs (2,2)-BRCGs are positive RCGs (Boullier, 1998) with binary start predicate names, i.e. ρ(S) = 2. In RCG, predicates can be negated (for complementation), and the start predicate name is typically unary. The definition is changed only for aesthetic reasons; a positive RCG with a binary start predicate name S is turned into a positive RCG with a

Towards Grammatical Inferencing of GDPLL(k) Grammars for Applications in Syntactic Pattern Recognition-Based Expert Systems

Abstract: The recent results of the research into construction of syntactic pattern recognition-based expert systems are presented. The model of syntactic pattern recognition has been defined with the use of GDPLL(k) grammars and parsers, and the model has been successfully applied as an efficient tool for inference support in several expert systems. Nevertheless, one of the main problems of practical application of GDPLL(k) grammars consists in difficulties in defining the grammar from the sample of a pattern language. In the paper we present the first achievement in the field of grammatical inferencing of GDPLL(k) grammars: an algorithm of automatic construction of a GDPLL(k) grammar from a so-called polynomial specification of the language.