Context Identification

Words like "stock" and "bear" have many different interpretations that depend strongly on the context Bryan Bell Presentation. Thus in the context of a financial discussion that touches on stocks the term "bear" is likely referring to investor or stock market attitude as opposed to a type of mammal. Context is fundamental to interpretation yet it is difficult to formalize the notion of context and perhaps the best stance is to agree with Pat Hayes [4] that there is no single meaning to context. At its core context includes the notions that some proposition, say "There are lots of bears in the stock market" that can be said to be true or false within a context. Saying, "There are lots of polar bears in the stock market" is most likely false due to context. What we understand as the context depends on context itself. Important work in this area was done by John McCarthy and Pat Hayes in their situation calculus, by Barwise, Perry and Devlin who developed situation theory [1], later formalized in OWL [2]. Situation theory is very popular in many domains, especially military and business domains.

Opportunities and Challenges

While situation theory is an effective formalization for context in many cases, it is not a complete solution to the notion of context. The challenge is to develop an effective formal notion of context that can be used to disambiguate the interpretation of words in human discourse and lead to what is called "understanding." Both situation calculus and situation theory support reasoning processes. Situation theory is especially versatile in this respect, allowing many forms of reasoning [3].

= Future Prospects

There is an abundant amount of work in NLP to try and take a degree of context into account. See the discussion of Cognitive Scaffolding for a related discussion. In the case of language understanding the context is often one of a discourse topic which can be represented as a larger knowledge structure such as by Discourse Analysis where themes are formalized as Ontology Design Patterns. At its extreme this work tends to looks at text and utterances not as having a unique, independent and objective information content, but as producing some understood content in the mind of the reader or hearer. In this sense meanings are conceptualized something to be constructed from propositions as ingredients along with a context.

References

[1] K. Devlin. Logic and Information. Cambridge University Press, Cambridge, U.K., 1991.

[2] K. Baclawski, M. Malczewski, M. Kokar, J. Letkowski, and C. Matheus. Formalization of situation awareness. In Eleventh OOPSLA Workshop on Behavioral Semantics, pages 1–15, Seattle, WA, November 4 2002.

[3] Baclawski, K. et al, Framework for Ontology-Driven Decision Making, Journal of Applied Ontology, to appear. [4] Hayes, Pat. "Contexts in context." Context in knowledge representation and natural language, AAAI Fall Symposium. 1997.