Hmm, that's an interesting argumentative fork to run into -- either a) SQL is Turing complete and departs from the relational algebra that the earlier post sai

Hmm, that's an interesting argumentative fork to run into -- either a) SQL is Turing complete and departs from the relational algebra that the earlier post said gave it a solid theoretical grounding, or b) SQL is not Turing complete, and so loses useful expressive power. For the actual fact of the matter, you're right. I had no idea. See https://wiki.postgresql.org/index.php?title=Cyclic_Tag_System&oldid=15106 https://wiki.postgresql.org/index.php?title=Cyclic_Tag_Syste... for concrete code. I think the specific departure from the "traditional" relational model that gets them there is "WITH RECURSIVE". I don't know whether there are other ways to get there. Personally I think it's the right side of the fork to land on.