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.

Probabilistic Context-Free Grammars Estimated from Infinite Distributions

Abstract: In this paper, we consider probabilistic context-free grammars, a class of generative devices that has been successfully exploited in several applications of syntactic pattern matching, especially in statistical natural language parsing. We investigate the problem of training probabilistic context-free grammars on the basis of distributions defined over an infinite set of trees or an infinite set of sentences by minimizing the cross-entropy. This problem has applications in cases of context-free approximation of distributions generated by more expressive statistical models. We show several interesting theoretical properties of probabilistic context-free grammars that are estimated in this way, including the previously unknown equivalence between the grammar cross-entropy with the input distribution and the so-called derivational entropy of the grammar itself. We discuss important consequences of these results involving the standard application of the maximum-likelihood estimator on finite tree and sentence samples, as well as other finite-state models such as hidden Markov models and probabilistic finite automata.

On the complexity of formal grammars

Abstract: The time and space complexity of the class of languages generated in linear time by context-sensitive grammars is investigated. Among other results it is shown that the membership question for languages in the class is NP-complete.

Constraining non-local dependencies in tree-adjoining grammar: computational and linguistic perspectives

Abstract: Working on Information Extraction and management of the TIDES (“Translingual Information Detection, Extraction and Summarization”) program at Penn. Helped develop Penn’s first contribution to the Automatic Content Extraction evaluation (pipelined statistical system). Current research is investigation of whether the notion of locality inherent in Tree Adjoining Grammar (TAG) will allow for an efficient approach to automatic extraction of predicate-argument structure. Developing software for tagging predicate argument structure of Chinese Treebank parse trees.

Feature Unification in TAG Derivation Trees

Abstract: The derivation trees of a tree adjoining grammar provide a first insight into the sentence semantics, and are thus prime targets for generation systems We define a formalism, feature-based regular tree grammars, and a translation from feature based tree adjoining grammars into this new formalism The translation preserves the derivation structures of the original grammar, and accounts for feature unification