I am trying to identify the appropriate fragment of Datalog containing rules of the type:


where B(x,z) is an IDB relation and c(z,y) is EDB relation. The special property of this fragment is the each free variable (i.e. a variable not in the head, z in this case) must appear at least twice. Put differently, the following rule is illeagal:


What is the name of this Datalog fragment and is there any complexity upper and/or lower bounds?


Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Browse other questions tagged or ask your own question.