- From: <jos.deroo@agfa.com>
- Date: Tue, 9 May 2006 22:59:42 +0200
- To: sandro@w3.org
- Cc: Francois Bry <bry@ifi.lmu.de>, public-rif-wg@w3.org
>> Sandro Hawke wrote: >> > >From WG discussions it seems like the right term is probably "Sequential >> > Horn Clauses with Prolog Syntax", >> >> What means for a clause to bew "sequential" or not to be "sequential"? A >> clause is a piece of text, and text is always "sequential", isn't it? >> >> Are you not referring instead to how the clauses are processed? Eg to a >> proof calculus or proof method? > >Yes, the naming is not perfect. The word "Sequential" is in there to >indicate that the order of clauses and the order of atoms within clauses >are significant. I'm not sure how significant they should be. > >1. Test case for answer ordering: > > Input ruleset (in SH-Prolog) > > x(a). > x(b). > > Answers to query: x(X) > > X = a; > X = b; > no > > Answers must be in that order. > >2. Test case for looping > > Input ruleset > > foo. > bar :- bar. > bar :- foo. > > Query: bar > > In normal (SLD-Resolution) Prologs, that query does not terminate. > In tabled Prologs like XSB, the answer is "yes". > >So, I don't really know which kind of language SH-Prolog should be to be >a suitable, simple, early example for RIF. > >Maybe we should have "SH-Prolog" which is like traditional Prologs on >the above tests, and "H-Prolog" in which order does not matter. >H-Prolog could be handled by XSB easily or re-written into depth-limited >rules for use in a normal Prolog engine and run with iterative >deepening. (That might not have 100% correct semantics, though.) > >Thoughts? Yes, I agree and see that you have been probably running those tests :) Also using a Prolog notation for your second test I was able to run it as well with euler5 (without looping forever) :- op(1200,xfx,'==>'). foo(a,b). bar(u,v) ==> bar(u,v). foo(a,b) ==> bar(u,v). bar(X,Y) ==> case(bar(X,Y)). % for the query and it answers with [ e:th {{a foo b} => {u bar v}}]. u bar v. which is N3 notation and I will second your "RIF must cover N3". -- Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/
Received on Tuesday, 9 May 2006 21:00:08 UTC