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：本文研究了带访问模式的合取查询（CQAPs）的时空权衡问题。目标是在初始预处理阶段构建空间高效的数据结构，并在在线阶段用于回答（多个）查询。先前的工作已针对实际感兴趣的查询（如路径查询和三角查询）开发了在空间使用与回答时间之间进行权衡的数据结构。然而，这些方法缺乏统一的框架且不具备泛化能力。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。该框架建立在$\PANDA$算法和树分解技术之上。我们证明了该框架能够涵盖独立为各种查询开发的所有现有先进权衡方案。此外，我们展示了在可达性查询方面对现有文献中已知先进权衡方案的显著改进。