Term logic is a logic system where the meanings and the derivation relations of sentences can be directly described as relations among terms (which correspond to nouns of natural language). Previously, we proposed the term logic system LVPM which can deal with compound terms corresponding to noun phrases modified by adjectives or relative clauses. This system was constructed as an axiomatic one, and its completeness under a set theoretical semantics was proved. In the system LVPM, a compound term is directly represented by an expression composed of terms and verb symbols. Thus, it has a unique character different from predicate logic where expressions are represented based on relations among individuals. In this paper, we consider a reasoning method for natural language sentences based on this logic system. Firstly, we provide a mechanical inference procedure for LVPM. Then, we construct a question-answering system by Japanese sentences based on LVPM. In this system, an input sentence is translated into an expression of the term logic, then if it is a declarative sentence, the expression for it is stored in the knowledge base, and if it is an interrogative one, an appropriate answer for it is produced by applying the inference procedure. Since this system is based on the term logic, the reasoning can be treated as direct operations for terms without decomposing into relations of individuals like as predicate logic.
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