Without thinking to much, it seems to me that a large set of Prolog's functionality could be implemented as relational calculus (a.k.a. SQL).
Has anyone heard of any tools to automatically convert Prolog to SQL?
+1
A:
Short answer: No. Although, at Uni I had to take some algorithms linked in a procedural pseduo-code and put them into Prolog. I'm thinking through how it'd work in SQL and I don't think you'd get enough of the core functionality.
In terms of list traversal, I don't see how you can do it relationally. You'll need to lean heavily on procedural constructs for it to work (for/loops, if statements, break (or whatever the equiv is in SQL for the cut). Was that what you were thinking or did you have anohter idea of how you'd go about it?
Martin Clarke
2009-04-07 06:55:17
Lists would be a real trick and might not even be possible.
BCS
2009-04-07 15:41:59
+2
A:
The mapping isn't very good. SQL, for example, doesn't do backtracking, unification, lists, or adhoc nested structures.
Prolog doesn't deal well with composite objects, indexes, etc.
I'd say it's a no-go.
MarkusQ
2009-04-07 06:56:02
I don't think you would need backtracking or unification as thing would be generated from the other end (with joins) OTOH this would kill all arbitrary depth recursion
BCS
2009-04-07 15:43:58
Without backtracking, unification, recursion, and lists there isn't a whole lot left of prolog. And you can't generate the same class of things with joins, unless you're thinking of writing self modifying SQL (queries that build queries) which I suppose is _possible_ but...
MarkusQ
2009-04-07 16:07:36
+8
A:
Yes, of course.
A premise for skeptics: any semi-decent book on database theory mentions Datalog (which is Prolog-like) and theorems which demonstrate that is possible to translate it to/from Relational Algebra (RA) (under specific restrictions).
SQL is not faithful to RA or relational calculi, but is enough to support Prolog:
- Christoph Draxler has developed a Prolog to SQL compiler (PL2SQL) for his thesis, available for download (.tgz) - also here at CMU Artificial Intelligence Repository (it was adapted and included in at least: Ciao Prolog and SWI-Prolog via Blipkit - Biomedical LogIc Programming Knowledge Integration Kit);
- Igor Wojnicki has developed for his PhD (A Rule-based Inference Engine Extending Knowledge Processing Capabilities of Relational Database Management Systems) a prototype system implementing his Jelly View technology called ReDaReS, but it seems not available for download;
- Relational Abstract Machine (RAM) translates Prolog to Relational Algebra, but it doesn't seems to have a SQL backend;
- Walter D. Potter has a couple of papers on Prolog/RDBMS integration;
- Kevin Boone's paper on Using SQL with Prolog to improve performance with large databases is also interesting;
- and so on...
MaD70
2009-11-05 18:12:27
A:
I would like to writte a SQL to prolog compiler... And I'am asking is this a right thing to do...
Thanks in advance, Robert...;) [email protected]
Robert
2010-06-30 12:42:14