Speaker
Affilliation
Open University
Abstract
In recent years textual entailment has been proposed as a framework for applied semantics that can be used for a wide range of real-world natural language processing applications. A series of PASCAL Challenges (RTE 1, 2, and 3) produced prototype systems that typically used a variety of (sometimes multiple) lexical semantic resources, many of which are available only for the English language.
I will give an overview of existing approaches and then describe in more detail the system devised by Gaston Burek and myself at the Open University. Our RTE-3 challenge entry differed from most other systems in that it relied exclusively on a shallowly parsed corpus as its sole resource. From this corpus, a fully automatic process based on Latent Semantic Analysis (LSA) extracted not only lexical semantic knowledge but also a certain amount of world knowledge -- something that is beyond the scope of most lexical knowledge bases, hand-crafted or automatically acquired. We expect that our approach could be a valuable component of many systems for recognising textual entailment -- even more so when systems are built for under-resourced languages.
To our knowledge, this is the first time that Latent Semantic Analysis does not operate on `bags of words' but on semi-structured (subject-verb-object) representations. Thus, in contrast to other LSA-based systems, our system will not claim that `Peter loves Mary' has the same meaning as `Mary loves Peter'.
== About the speaker ==
Christian Pietsch studied linguistics and informatics at the Universities of Leipzig and Edinburgh before going on to study computational linguistics at Saarland University, Saarbruecken, where he wrote his masters' thesis on robust natural language generation at DFKI, graduating in 2005. Since February 2006, he has been a member of Donia Scott's Natural Language Generation research group at the Open University. There he met Gaston Burek who is finishing a PhD thesis involving semantic similarity detection using LSA. To put some of his ideas to the test, they decided to build a system for the RTE-3 challenge.