In this paper, we investigate space-time tradeoffs for answering conjunctive queries with access patterns (CQAPs). The goal is to create a space-efficient data structure in an initial preprocessing phase and use it for answering (multiple) queries in an online phase. Previous work has developed data structures that trades off space usage for answering time for queries of practical interest, such as the path and triangle query. However, these approaches lack a comprehensive framework and are not generalizable. Our main contribution is a general algorithmic framework for obtaining space-time tradeoffs for any CQAP. Our framework builds upon the $\PANDA$ algorithm and tree decomposition techniques. We demonstrate that our framework captures all state-of-the-art tradeoffs that were independently produced for various queries. Further, we show surprising improvements over the state-of-the-art tradeoffs known in the existing literature for reachability queries.

翻译：在本文中，我们研究了具有访问模式的合取查询（CQAP）的时空权衡。目标是在初始预处理阶段创建一个空间高效的数据结构，并用于在线阶段回答（多个）查询。先前的工作已经开发出针对实际感兴趣查询（如路径查询和三角形查询）在空间使用与回答时间之间进行权衡的数据结构。然而，这些方法缺乏统一框架，且不可泛化。我们的主要贡献是一个通用的算法框架，可为任意CQAP实现时空权衡。该框架基于$\PANDA$算法和树分解技术构建。我们证明，该框架涵盖了先前独立为多种查询开发的所有最先进权衡。此外，我们针对现有文献中可达性查询的最优权衡展示了令人惊喜的改进。