Articles

Dominance constraints are logical descriptions of trees that are widely used in computational linguistics. Their general satisfiability problem is known to be NP-complete. Here we identify the natural fragment of normal dominance constraints and show that its satisfiability problem is in deterministic polynomial time. 1...

In terms of both speed and mem- ory consumption, graph unification remains the most expensive com- ponent of unification-based gram- mar parsing. We present a tech- nique to reduce the memory usage of unification algorithms consider- ably, without increasing execution times. Also, the proposed algorithm is thread-safe, providing an efficient …...

Extractive summarization techniques cannot generate document summaries shorter than a single sentence, some- thing that is often required. An ideal summarization system would under- stand each document and generate an appropriate summary directly from the results of that understanding. A more practical approach to this problem re- sults in the …...

This paper introduces a statistical model for query-relevant summarization: succinctly characterizing the relevance of a document to a query. Learning parameter values for the proposed model requires a large collec- tion of summarized documents, which we do not have, but as a proxy, we use a col- lection of FAQ …...

This paper reports the first part of a project that aims to develop a knowledge extrac- tion and knowledge discovery system that extracts causal knowledge from textual da- tabases. In this initial study, we develop a method to identify and extract cause-effect information that is explicitly expressed in medical abstracts …...

The noisy channel model has been applied to a wide range of problems, including spelling correction. These models consist of two components: a source model and a channel model. Very little research has gone into improving the channel model for spelling correction. This paper describes a new channel model for …...

Chinese input is one of the key challenges for Chinese PC users. This paper proposes a statistical approach to Pinyin-based Chinese input. This approach uses a trigram-based language model and a statistically based segmentation. Also, to deal with real input, it also includes a typing model which enables spelling correction …...

The paper develops a constraint-based the- ory of prosodic phrasing and prominence, based on an HPSG framework, with an implementation in ALE. Prominence and juncture are represented by n-ary branching metrical trees. The general aim is to define prosodic structures recursively, in parallel with the definition of syntactic structures. We …...

We present a clustering algorithm for Arabic words sharing the same root. Root based clusters can substitute dictionaries indexing for IR. Modifying Adamson andin Boreham (1974), our Two-stage algorithm applies light stemming before calculating word pair similarity coefficients using techniques sensitive to Arabic morphology. Tests show a successful treatment of …...

In this paper, a computational approach for resolving zero-pronouns in Spanish texts is proposed. Our approach has been evaluated with partial parsing of the text and the results obtained show that these pronouns can be resolved using similar techniques that those used for pronominal anaphora. Compared to other well-known baselines …...

We have developed a system that generates evaluative arguments that are tailored to the user, properly arranged and concise. We have also developed an evaluation framework in which the effectiveness of evaluative arguments can be measured with real users. This paper presents the results of a formal experiment we have …...

This paper presents a novel statistical model for automatic identification of English baseNP. It uses two steps: the N- best Part-Of-Speech (POS) tagging and baseNP identification given the N-best POS-sequences. Unlike the other approaches where the two steps are separated, we integrate them into a unified statistical framework. Our model …...

Prepositional phrase attachment is common source of ambiguity in naturala language processing. We present an unsupervised corpus-based approach to prepositional phrase attachment that achieves similar performance to supervised methods. Unlike previous unsupervised approaches in which training data is obtained by heuristic extraction of unambiguous examples from a corpus, we use …...

Spoken dialogue managers have benefited from using stochastic planners such as Markov Decision Processes (MDPs). How- ever, so far, MDPs do not handle well noisy and ambiguous speech utterances. We use a Partially Observable Markov Decision Pro- cess (POMDP)-style approach to generate dialogue strategies by inverting the notion of dialogue …...

We introduce an annotation scheme for temporal expressions, and describe a method for resolving temporal expressions in print and broadcast news. The system, which is based on both hand-crafted and machine-learnt rules, achieves an 83.2% accuracy (F- measure) against hand-annotated data. Some initial steps towards tagging event chronologies are also …...

We present an LFG-DOP parser which uses fragments from LFG-annotated sentences to parse new sentences. Experiments with the Verbmobil and Homecentre corpora show that (1) Viterbi n best search performs about 100 times faster than Monte Carlo search while both achieve the same accuracy; (2) the DOP hypothesis which states …...

Experimental studies of interactive language use have shed light on the cognitive and interpersonal processes that shape conversation; corpora are the emergent products of these processes. I will survey studies that focus on under-modelled aspects of interactive language use, including the processing of spontaneous speech and disfluencies; metalinguistic displays such …...

We present an evaluation of domain- independent natural language tools for use in the identification of significant concepts in documents. Using qualitative evaluation, we compare three shallow processing methods for extracting index terms, i.e., terms that can be used to model the content of documents. We focus on two criteria: …...

Information retrieval systems have typically concen- trated on retrieving a set of documents which are rel- evant to a user's query. This paper describes a sys- tem that attempts to retrieve a much smaller section of text, namely, a direct answer to a user's question. The SMART IR system is …...

This paper describes experiments to establish the performance of a named entity recognition system which builds categorized lists of names from manu- ally annotated training data. Names in text are then identified using only these lists. This approach does not perform as well as state-of-the-art named en- tity recognition systems. …...