Invariant Mappings and Contexts in a Computational Approach to Metaphor Interpretation R. Agerri, J.A. Barnden, M.G. Lee, A.M. Wallington School of Computer Science, Univ. of Birmingham B15 2TT Birmingham, UK {R.Agerri,J.A.Barnden,M.G.Lee,A.M.Wallington}@cs.bham.ac.uk Abstract We start by characterizing the role of a set of invariant mappings within a se- mantic framework for metaphor interpre- tation. Such rules are defaults and have previously been identified by our group as invariant mappings adjuncts to any con- ceptual metaphor. We provide a formal description of several invariant mappings that transfer information such as causation and event degrees, and discuss some issues with respect to their implementation in a pre-existing AI system (ATT-Meta). 1 Introduction It is generally accpeted that much of everyday language shows evidence of metaphor. Although some work has been done on the semantics of metaphor (Asher and Lascarides, 1995; Stern, 2000), it is not yet clear what the relation is be- tween the semantics and pragmatics of metaphor interpretation from a computational point of view. We assume the general view that metaphor un- derstanding involves some notion of events, prop- erties, relations, etc. that are transferred from the source domain into the target domain. In this view, a metaphorical utterance conveys in- formation about the target domain. We investi- gate and account for the transfer of information from source to target as a relation between two computational contexts: the pretence cocoon and the reality. The ATT-Meta system (Barnden and Lee, 2002) performs within-pretence inferencing so that we can derive, from the initial utterance, information that can be transferred into the re- ality using correspondences provided by the ex- isting conceptual metaphor (in our terminology, “metaphorical view”). In our approach, this rea- soning takes place in the special, protected com- putational context called the “pretence context”. We use the term ‘reality’ to refer to the space in which the information conveyed by a metaphori- cal utterance is transferred to. Some authors have tacitly assumed that there is evidence for the existence of aspects that invari- ably map from pretence to reality, whatever the metaphorical view is in play (Lakoff, 1993). We address the issue in more detail and describe and formalize a set of view-neutral mapping adjuncts (VNMAs) which transfer those aspects that are not part of any specific metaphorical view. More- over, we claim that VNMAs can be seen as de- fault rules. Furthermore, we introduce a general semantic framework for metaphor by characteriz- ing the meaning relation between the two contexts as consisting of the central mappings provided by the metaphorical view in play, and the set of de- fault rules that transfer invariant aspects from the pretence to the reality. The next section introduces a general seman- tic framework for metaphor and discuss the role of VNMAs in such a framework. Section 3 illus- trates the notion of within-pretence reasoning in the ATT-Meta approach and system to metaphor interpretation. Section 4 describes two important VNMAs, and in section 5 we present their formal- ization. We discuss several issues about the im- plementation of the VNMAs in section 6. Finally, section 7 presents some conclusions and discus- sion on related work. 2 Mappings in a Semantic Framework for Metaphor We propose to adapt the Situation Theoretic Dis- course Representation Theory (STDRT) of Cooper