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We describe our submission to the PASCAL Recognizing Textual Entailment Challenge, which attempts to isolate the set of Text-Hypothesis pairs whose categorization can be accurately predicted based solely on syntactic cues. Two human annotators examined each pair, showing that a surprisingly large proportion of the data – 34% of the test items – can be handled with syntax alone, while adding information from a general-purpose thesaurus increases this to 48%.

This paper addresses Textual Entailment (i.e. recognizing that the meaning of a text entails the meaning of another text) using a Tree Edit Distance algorithm between the syntactic trees of the two texts. A key aspect of the approach is the estimation of the cost for the editing operations (i.e. Insertion, Deletion, Substitution) among words.

The aim of the paper is to compare the contribution of two different lexical resources for recognizing textual entailment: WordNet and a word-similarity database. In both cases we derive entailment rules that are used by the Tree Edit Distance Algorithm. We carried out a number of experiments over the PASCAL-RTE dataset in order to estimate the contribution of different combinations of the available resources.

The Recognizing Textual Entailment System shown here is based on the use of a broad-coverage parser to extract dependency relationships; in addition, relations are used to recognize entailment at the lexical level. The work investigates whether the mapping of dependency trees from text and hypothesis give better evidence of entailment than the matching of plain text alone. While the use of seems to improve system’s performance, the notion of mapping between trees here explored (inclusion) shows no improvement, suggesting that other notions of tree mappings should be explored such as tree edit distances or tree alignment distances.

Textual Entailment recognition is a very difficult task as it is one of the fundamental problems in any semantic theory of natural language. As in many other NLP tasks, Machine Learning may offer important tools to better understand the problem. In this paper, we will investigate the usefulness of Machine Learning algorithms to address an apparently simple and well defined classification problem: the recognition of Textual Entailment. Due to its specificity, we propose an original feature space, the , where we model the distance between the elements of the candidate entailment pairs. The method has been tested on the data of the Recognizing Textual Entailment (RTE) Challenge.

is the problem of determining if the meaning of a given sentence entails that of another. We present a principled approach to semantic entailment that builds on inducing re-representations of text snippets into a hierarchical knowledge representation along with an optimization-based inferential mechanism that makes use of it to prove semantic entailment. This paper provides details and analysis of the knowledge representation and knowledge resources issues encountered. We analyze our system’s behavior on the PASCAL text collection and the PARC collection of question-answer pairs. This is used to motivate and explain some of the design decisions in our hierarchical knowledge representation, that is centered around a predicate-argument type abstract representation of text.

This paper describes the Bar-Ilan system participating in the Recognising Textual Entailment Challenge. The paper proposes first a general probabilistic setting that formalizes the notion of textual entailment. We then describe a concrete alignment-based model for lexical entailment, which utilizes web co-occurrence statistics in a bag of words representation. Finally, we report the results of the model on the challenge dataset along with some analysis.

The PASCAL Challenge’s textual entailment recognition task, or RTE, presents intriguing opportunities to test various implications of the strong language universal constraint posited by Wu’s (1995, 1997) Inversion Transduction Grammar (ITG) hypothesis. The ITG Hypothesis provides a strong inductive bias, and has been repeatedly shown empirically to yield both efficiency and accuracy gains for numerous language acquisition tasks. Since the RTE challenge abstracts over many tasks, it invites meaningful analysis of the ITG Hypothesis across tasks including information retrieval, comparable documents, reading comprehension, question answering, information extraction, machine translation, and paraphrase acquisition. We investigate two new models for the RTE problem that employ simple generic Bracketing ITGs. Experimental results show that, even in the absence of any thesaurus to accommodate lexical variation between the Text and the Hypothesis strings, surprisingly strong results for a number of the task subsets are obtainable from the Bracketing ITG’s structure matching bias alone.

In this paper, we discuss paradigms for evaluating open-domain semantic interpretation as they apply to the PASCAL Recognizing Textual Entailment (RTE) evaluation (Dagan et al. 2005). We focus on three aspects critical to a successful evaluation: creation of large quantities of reasonably good training data, analysis of inter-annotator agreement, and joint analysis of test item difficulty and test-taker proficiency (Rasch analysis). We found that although RTE does not correspond to a “real” or naturally occurring language processing task, it nonetheless provides clear and simple metrics, a tolerable cost of corpus development, good annotator reliability (with the potential to exploit the remaining variability), and the possibility of finding noisy but plentiful training material.

The Computational Linguistics at Concordia laboratory system for textual entailment determination is based on shallow, partial predicate-argument structure matching combined with a WordNet-based lexical similarity measure. In this paper we describe experiments with different system settings conducted to assess the potential and limitations of partial predicate-argument structures in textual entailment determination.

The system for semantic evaluation VENSES (Venice Semantic Evaluation System) is organized as a pipeline of two subsystems: the first is a reduced version of GETARUN, our system for Text Understanding. The output of the system is a flat list of augmented head-dependent structures with Grammatical Relations and Semantic Roles labels. The evaluation system is made up of two main modules: the first is a sequence of linguistic rules; the second is a quantitatively based measurement of input structures and predicates. VENSES measures semantic similarity which may range from identical linguistic items, to synonymous, lexically similar, or just morphologically derivable. Both modules go through General Consistency checks which are targeted to high level semantic attributes like presence of modality, negation, and opacity operators, temporal and spatial location checks. Results in cws, recall and precision are homogeneous for both training and test corpus and fare higher than 60%.