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## Re: [ontolog-forum] Logic, Datalog and SQL

 To: "John F. Sowa" "[ontolog-forum] " Pat Hayes Thu, 8 Feb 2007 17:12:12 -0600
 ```>Folks, > >I completely support Pat's discussion of closed worlds >and open worlds. This is not a "debate", but a discussion >of how to handle two kinds of databases, both of which >are important for various applications: > > 1. Open worlds, such as information derived from > observation, in which the absence of an entry > does not imply its negation. > > 2. Closed worlds, such as information derived from > an exhaustive enumeration or a declaration by fiat; > i.e., anyone whose reservation has not been entered > in the database does not have a reservation. > >Both kinds arise in many applications, and both must >be supported. I also agree with Pat that the term >"negation as failure" is misleading and that "negation >by inference" is a better term. > >Once you adopt that term, you can begin to ask what >kinds of inferences should be supported. Failure >to prove (or observe) is a common basis for the >inference, but there can be more subtle variations. > >For example, the fact that I haven't observed an >elephant in my living room allows me to infer with >high probability that no elephant is lurking there. >But my failure to observe any bacteria in the living >room does not imply their absence.    (01) Right. There is a fascinating line of research, BTW, on inferences which people make intuitively, seem to be surprisingly reliable, and seem to have the general form "If x were y, I would know about it; I havn't heard of x; therefore x isn't y" This enables for example German students to make reliable guesses about which American cities are larger than others. I first heard of this in the work of Gerd Gigerenzer on 'bounded rationality'. See http://en.wikipedia.org/wiki/Recognition_heuristic    (02) What I find fascinating is that this seems to depend on there being just the right amount of generally available public information, a lot but not all of it. It wouldn't have worked in a medieval society and it might not work in the future for the opposite reason: people will all know too much.    (03) > >Having thrown in this bit of support, I'd like to make >a brief comment on our argument about models and reality: > > 1. Pat prefers to identify the model with the thing > that is modeled, except in circumstances when the > thing modeled may not exist or may be difficult > to observe in sufficient detail.    (04) That isn't how I would put it myself :-)    (05) > 2. I prefer to make a distinction between the two in > all cases, but allow the option of saying that they > may sometimes be identical or at least isomorphic.    (06) I will agree that an interpretation need not *always* be made up of real stuff, as it were. In fact it is easy to show that this is false: if an ontology has any satisfying interpretations at all, then it has a Herbrand interpretation entirely made of symbols. My only point was that it is *possible* to interpret ontologies directly against the actual world (and this is often a useful thing to do, if only as part of a thought experiment.)    (07) > >This reduces the debate to a question of relative importance >or frequency. > >But there is one important reason for making the distinction >between the model and the thing modeled: it allows the >possibility of discussing and comparing different models and >deciding which one(s) have a better correspondence with >reality.    (08) Oh, sure. But here you are using "model" in what I called the model-2 sense, right, rather than the Tarskian sense used in "model theory". Then this becomes the Korzybskian slogan that the map is not the territory: which is true, of course.    (09) Pat    (010) > >John > > >_________________________________________________________________ >Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/  >Subscribe/Config: http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/  >Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx >Shared Files: http://ontolog.cim3.net/file/ >Community Wiki: http://ontolog.cim3.net/wiki/ >To Post: mailto:ontolog-forum@xxxxxxxxxxxxxxxx >    (011) -- --------------------------------------------------------------------- IHMC (850)434 8903 or (650)494 3973 home 40 South Alcaniz St. (850)202 4416 office Pensacola (850)202 4440 fax FL 32502 (850)291 0667 cell phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes    (012) _________________________________________________________________ Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/ Subscribe/Config: http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/ Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx Shared Files: http://ontolog.cim3.net/file/ Community Wiki: http://ontolog.cim3.net/wiki/ To Post: mailto:ontolog-forum@xxxxxxxxxxxxxxxx    (013) ```
 Current Thread [ontolog-forum] Logic, Datalog and SQL, Adrian Walker Re: [ontolog-forum] Logic, Datalog and SQL, Ed Barkmeyer Re: [ontolog-forum] Logic, Datalog and SQL, Adrian Walker Re: [ontolog-forum] Logic, Datalog and SQL, Pat Hayes Re: [ontolog-forum] Logic, Datalog and SQL, John F. Sowa Re: [ontolog-forum] Logic, Datalog and SQL, Pat Hayes <= Re: [ontolog-forum] Logic, Datalog and SQL, John F. Sowa Re: [ontolog-forum] Logic, Datalog and SQL, Pat Hayes Re: [ontolog-forum] Logic, Datalog and SQL, Christopher Menzel Re: [ontolog-forum] Logic, Datalog and SQL, Charles D Turnitsa Re: [ontolog-forum] Logic, Datalog and SQL, Pat Hayes Re: [ontolog-forum] Logic, Datalog and SQL, Kathryn Blackmond Laskey Re: [ontolog-forum] Logic, Datalog and SQL, Ed Barkmeyer Re: [ontolog-forum] Logic, Datalog and SQL, Pat Hayes Re: [ontolog-forum] Logic, Datalog and SQL, Christopher Menzel Message not availableMessage not availableRe: [ontolog-forum] Logic, Datalog and SQL, Adrian Walker