Datasheet程序的右伴随与限制类上的同态对偶
Right-Adjoints for Datalog Programs, and Homomorphism Dualities over Restricted Classes
摘要：
一个数据库程序可以被看作是一个函子的语法规范，从一个模式上的数据库实例到另一个模式上的数据库实例。对于$\exists$数据库，这一点更普遍。我们建立了大类的Datasheet和$\exists$ Datasheet程序，相应的函子承认一个广义右伴随。我们采用这些结果，以获得新的见解的存在，和方法构建，同态对偶限制类的实例。我们还得出了新的结果，唯一表征数据库查询的数据示例的存在。
英文摘要：
A Datalog program can be viewed as a syntactic specification of a functor from database instances over some schema to database instances over another schema. The same holds more generally for $\exists$Datalog. We establish large classes of Datalog and $\exists$Datalog programs for which the corresponding functor admits a generalized right-adjoint. We employ these results to obtain new insights into the existence of, and methods for constructing, homomorphism dualities within restricted classes of instances. We also derive new results regarding the existence of uniquely characterizing data examples for database queries.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
