Textual Entailment

The goal of identifying Textual Entailment - whether one piece of text can be plausibly inferred from another - has emerged in recent
years as a generic core problem in Natural Language Understanding.
Work in this area has been largely driven by the PASCAL Recognizing Textual Entailment (RTE) challenges (http://pascallin.ecs.soton.ac.uk/Challenges/RTE/), a series of annual competitive meetings. This work exhibits strong ties to some earlier lines of research, particularly automatic acquisition of paraphrases and lexical semantic relationships, and unsupervised inference in applications such as question answering, information extraction and summarization.

Since 2008 RTE is organized by NIST as part of the Text Analysis Conference (TAC).
TAC Recognizing Textual Entailment Track http://www.nist.gov/tac/2009/RTE/

The Textual Entailment Resource Pool
(http://aclweb.org/aclwiki/index.php?title=Textual_Entailment_Resource_Po...) hosted by ACL provides a repository of linguistic tools and resources for textual entailment.