Metaphor as an Emergent Property of Machine-Readable Dictionaries

Previous computational attempts to handle non-literal word usage have been restricted to systems that combine hand-coded lexicons with restricted sets of metaphor types that can be used to sanction specific classes of semantic subcategorization violations. These hand-coded efforts are unlikely to ever scale up to the rigors of real, free text. We describe an example-based approach to metaphor interpretation which exploits a large lexical knowledge base derived from a machine-readable dictionary. We first present an extended example which is meant to demonstrate the scope of evidence about common English metaphors which is encoded in ordinary dictionaries. We then go on to demonstrate how novel instances of metaphor can be interpreted by accessing this information. A given violation of some default semantic expectation can be checked against the LKB to determine whether this violation is an instance of some more systematic mapping of English word meanings from one semantic domain to another. We argue that this approach to metaphor interpretation obviates the need for the traditional “metaphor-handling component” in natural language understanding systems, and will allow these systems to overcome the brittleness of hand-coded approaches.