CONCEPTUAL OVERLAYS: A MECHANISM FOR THE INTERPRETATION OF SENTENCE MEANING IN CONTEXT

摘要

This paper describes a context mechanism f o r a natural language understanding system. Since no sentence is ever perceived outside some context, it is reasonable to inquire into the nature of context as it affects the inter predation of sentence meaning at a deep conceptual level. A theory, called conceptual overlays, is described. This theory (1) defines C (T_1,..., T_i), the context established by the meaningful sequence of thoughts T_1 T_j: (2) defines I(T_(j+1), C (T_1,... T_j)), the high-level interpretation of T_(i+i) in the context established by T_i,..., T_i; and (3) specifies an effective algorithm and data structure for computing I (t, K) for arbitrary thought T in context K. In particular, a prototype LISP system, EX-SPECTRE-1, which solves simple cases of I (T_2.,C(T_1)) is described. The system is based on an expectancy/fulfillment paradigm. Expectancies are spontaneously activated by a pattern directed invocation technique. Each expectancy implicitly references large chunks of common - sense algorithms. A collection of such implicitly activated algorithms constitutes context, and the interpretive process is one of identifying future input as steps in these algorithms. Context switching and uses of I (T, K) in a language comprehension system are discussed.