Declarative Features for Deductive Databases

演绎数据库为编写查询提供了基于一阶逻辑的声明性框架。数据库中的条目定义查询的答案，但不指示如何回答查询。通过允许递归，演绎数据库比经典关系数据库具有更高的表达能力。这个项目解决的两个主要问题是语义和优化。本文研究了用“最小”和“和”等聚合运算符扩展的演绎数据库的语义问题。还考虑了将这种语义扩展到具有二阶结构的程序。该项目正在评估如何有效地将二阶特性合并到当前的关系数据库中。本文还研究了具有聚合的演绎数据库的优化技术，包括新技术和现有策略的扩展。该项目将提供关于如何在演绎数据库中提供声明性特性（如聚合和二阶结构）的基础知识。

Deductive databases provide a declarative framework based on first-order logic for writing queries. Entries in the database define the answer to a query without indicating how to answer the query. By allowing recursion, deductive databases yield higher expressive power than classical relational databases. The two main problems addressed in this project are semantics and optimization. This research studies semantics for deductive databases extended with aggregate operators such as ``minimum'' and ``sum.'' Extensions of such semantics to programs with second-order constructs are also considered. The project is assessing how effectively second-order features can be incorporated into present-day relational databases. Optimization techniques for deductive databases with aggregates, both new techniques and extensions of existing strategies are also be investigated. This project will contribute fundamental knowledge about how to provide declarative features, such as aggregation and second-order constructs, within deductive databases.