Topic
Context-sensitive grammar
About: Context-sensitive grammar is a research topic. Over the lifetime, 1938 publications have been published within this topic receiving 45911 citations. The topic is also known as: CSG.
Papers published on a yearly basis
Papers
More filters
••
15 Dec 2004TL;DR: The composite directed MRF model has a potentially exponential number of loops and becomes a context sensitive grammar, nevertheless it is able to estimate its parameters in cubic time using an efficient modified ME method, the generalized inside-outside algorithm, which extends the inside- outside algorithm to incorporate the effects of the n-gram and PLSA language models.
Abstract: We present a directed Markov random field (MRF) model that combines n-gram models, probabilistic context free grammars (PCFGs) and probabilistic latent semantic analysis (PLSA) for the purpose of statistical language modeling. Even though the composite directed MRF model potentially has an exponential number of loops and becomes a context sensitive grammar, we are nevertheless able to estimate its parameters in cubic time using an efficient modified EM method, the generalized inside-outside algorithm, which extends the inside-outside algorithm to incorporate the effects of the n-gram and PLSA language models. We generalize various smoothing techniques to alleviate the sparseness of n-gram counts in cases where there are hidden variables. We also derive an analogous algorithm to calculate the probability of initial subsequence of a sentence, generated by the composite language model. Our experimental results on the Wall Street Journal corpus show that we obtain significant reductions in perplexity compared to the state-of-the-art baseline trigram model with Good-Turing and Kneser-Ney smoothings.
16 citations
••
TL;DR: The article presents proofs of the context freeness of a family of typelogical grammars that are based on a uni- or multimodal logic of pure residuation, possibly enriched with the structural rules of Permutation and Expansion for binary modes.
Abstract: The article presents proofs of the context freeness of a family of type logical grammars, namely all grammars that are based on a uni- or multimodal logic of pure residuation, possibly enriched with the structural rules of Permutation and Expansion for binary modes
16 citations
••
23 Sep 1996TL;DR: Current approaches to weighted constraint logic grammars attempt to address this issue by adding numerical calculation schemata to the deduction scheme of the underlying CLP framework.
Abstract: Constraint logic grammars provide a powerful formalism for expressing complex logical descriptions of natural language phenomena in exact terms. Describing some of these phenomena may, however, require some form of graded distinctions which are not provided by such grammars. Recent approaches to weighted constraint logic grammars attempt to address this issue by adding numerical calculation schemata to the deduction scheme of the underlying CLP framework.
16 citations
••
TL;DR: The main point of this paper is the systematic study of all possibilities of defining leftmost derivation in matrix grammars and finds a characterization of the recursively enumerable languages for matrix Grammars with the leftmost restriction defined on classes of a given partition of the nonterminal alphabet.
Abstract: Matrix grammars are one of the classical topics of formal languages, more specifically, regulated rewriting. Although this type of control on the work of context-free grammars is one of the earliest, matrix grammars still raise interesting questions (not to speak about old open problems in this area). One such class of problems concerns the leftmost derivation (in grammars without appearance checking). The main point of this paper is the systematic study of all possibilities of defining leftmost derivation in matrix grammars. Twelve types of such a restriction are defined, only four of which being discussed in literature. For seven of them, we find a proof of a characterization of recursively enumerable languages (by matrix grammars with arbitrary context-free rules but without appearance checking). Other three cases characterize the recursively enumerable languages modulo a morphism and an intersection with a regular language. In this way, we solve nearly all problems listed as open on page 67 of the monograph [7], which can be seen as the main contribution of this paper. Moreover, we find a characterization of the recursively enumerable languages for matrix grammars with the leftmost restriction defined on classes of a given partition of the nonterminal alphabet.
16 citations