The authors developed a language QUIXOTE as a tool to deal with various information in natural language processing. QUIXOTE is a hybrid language of a deductive object-oriented database and constraint logic programming language. The new mechanism of QUIXOTE is a combination of an object-orientation concept such as object identity and the concept of a module that classifies a large knowledge base. In addition, its logical inference system is extended to be able to make restricted abduction. The authors first apply QUIXOTE to the sorted feature structure of constraint-based grammar formalisms. Next, it is shown that QUIXOTE can contribute to the description of situation-based semantics. The authors have implemented a system to make abductive reasoning to clarify hidden information. Also, they resolve the problem of noun phrase reference.

A description is given of parallel control techniques and performance evaluations by simulation for the knowledge-base machine (KBM) using the multiport page-memory (MPPM) and the unification engine (UE). Relational knowledge base retrieval requires repeated application of the unification-join (U-join) operations on term relations. It also requires each U-join to be dynamically scheduled, observing the result of the previously executed U-join. Control techniques to execute the query process of the relational knowledge base effectively in the KBM using the MPPM and the UE have been investigated. For parallel execution of coarse-grain operations, each operation is decomposed to concurrently executable fine-grain operations by partitioning input data sets. A number of features that depend on processor-allocation strategies have been identified. In particular, it was found that query processing resulting in repetitions of the retrieval operation, by a certain control strategy, increases the amount of the total data transfer to the highly parallel UEs and lowers processing efficiency.>