I feel like this came up somewhat recently, but I can't find the context.

In any case, I wonder how it compares to Screamer, ACL2, and Kanren.

EDIT: found it: https://news.ycombinator.com/item?id=41805702 (6 comments)

It also came up this recent thread https://news.ycombinator.com/item?id=42445328

ACL2 is a proof assistant. AP5 seems to be more of a relational data structure language.