> I'm afraid that adding existentials to rule heads pushes the language > outside of Horn. In fact, we would nearly have full first-order logic > (the only thing that is missing is destruction); not a rule language. s/destruction/disjunction/ This was a speech recognition error, and I neglected to read over the text before sending it off. So, the Freudian slip was by my (perhaps not unintelligent) speech recognition system :-) Best, Jos > Adding conjunction to rule heads is not a problem, because conjunctions > can be split into several rules with atomic formulas in the heads. > > Best, Jos > > Sandro Hawke wrote: >> In planning to implement RIF for N3, the two extensions I mostly need >> are to allow existentials and conjunctions in the the rule consequents. >> These are straightforward extensions, with nice fallback rewrites, but I >> thought I would just raise the question of putting them directly in BLD. >> >> I note, in particular, that Production Rule systems want something very >> much like existentials in the consequent, too, so this might possibly >> even go into Core. But maybe it's not exactly the same thing, and >> datalog certainly doesn't have it. >> >> I'm fine working with this as just an extension, but I thought I should >> at least raise the issue in case anyone else is sympathetic. >> >> - Sandro >> > -- debruijn@inf.unibz.it Jos de Bruijn, http://www.debruijn.net/ ---------------------------------------------- One man that has a mind and knows it can always beat ten men who haven't and don't. -- George Bernard ShawReceived on Friday, 23 May 2008 14:18:25 UTC
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