|From:||Jairo Cardona Giraldo <cardona6i@xxxxxxxxx>|
|Date:||Sat, 3 Mar 2007 05:21:40 -0800 (PST)|
----- Mensaje original ----
De: Elisa F. Kendall <ekendall@xxxxxxxxxxxx>
Para: [ontolog-forum] <ontolog-forum@xxxxxxxxxxxxxxxx>
Enviado: martes, 27 de febrero, 2007 16:07:16
Asunto: Re: [ontolog-forum] Ontologies and Algebraic Specifications
I've been following the exchange with Pat, John Sowa, etc. commenting on your thoughts. Would it be helpful to you if I could take one or more of the owl ontology components we've built in VOM, show you the OWL (pointing out which constructs correspond to quantifiers, etc., and translate it to FOL so that you can see what it would say in a first order representation?
I hadn't thought to do this previously, though I don't know why :). Based on Steve's recent musings on the value or lack thereof of ontologies, at least for this application, I've thought seriously about providing the translation to FOL and augmenting that with additional axioms you can't say in OWL, then using -that- in JTP or some other FOL reasoner, possibly KM from the Univ. of Texas, which claims to be able to reason about actions using a situations mechanism, or the two in parallel, just to be a skeptic ... and to think about reasoning that includes hypothesis testing.
Just thinking about things out loud with you, since I've been stewing on these things in the background since I was in LA last week.
Horning, Jim wrote:
Pat, Thanks, that clarifies a lot. Now let me see how I can do with the "much, much greater than" message format that this list prefers. :-) Jim H.-----Original Message----- From: Pat Hayes [mailto:phayes@xxxxxxx] Sent: Tuesday, February 27, 2007 7:37 AM To: Horning, Jim Cc: ontolog-forum@xxxxxxxxxxxxxxxx Subject: Re: Ontologies and Algebraic Specifications...- *traits* [modules/units/components] that are the concrete elements of discourse. The body of a trait may refer to other traits and include *declarations*, *axioms*, and *consequences*. Axioms are mostly, but not exclusively, equations.That seems very odd to me, speaking from the ONT side. There are many things one wants to say that just can't be put into equational form.Yes, there are other things, and LSL has other forms of axioms for those things that we found to be important in specifying abstract data types and functions. I would like to know what other things it is important to say in ontologies, and what forms of axioms are best suited to saying them. (LSL treats universally-quantified first-order logical expressions as a special case of equations.) ...- *units* [modules/units/component] that are the concrete elements of discourse. The body of a unit may *import* from, and *export* to, other units and will include *type declarations* and possibly some *constraints*.Hmm. Im not sure what you mean by a 'unit' here. (Common Logic has a 'module' construction, but that has a special purpose of limiting the 'local' universe of discourse.)All I was trying to say is that I believe most ontologies are not written indivisibly as one [block of text/diagram/formula/file/page], but are written and presented in chunks (which might be called different things in different ONT languages). This subdivision might or might not have semantic significance in a particular ONT language (e.g., scoping of names and quantifiers). These chunks have to be named or identified somehow in other chunks; their relations constitute a "gross anatomy" of the presentation.This seems to miss the central point, which is that an ontology is, at base, a theory; that is, a collection of sentences. Plus, maybe, some bells and whistles, but in many cases even those are re-understood as kinds of sentence (e.g. 'imports'). Some languages have types which may in some cases require declarations, but these are not an essential part of the mix.No, IMHO this is one of the points that I have not missed. However, I fear, some in this community have overlooked it or gotten it wrong: The presentation is not the same thing as what the presentation denotes. What I write in an ONT language is not the same as the associated theory. I don't care which one you call "the ontology," but you also need to have a name for the other one, and any reader needs to know which you mean where.Importing is a Web idea, and there is no such thing as "exporting" (AFAIK).My mistake. I thought the discussion I had seen here of import and export related to ontologies. E.g., John F. Sowa "I also added two special kinds of statements: 'Import' for those types that are specified elsewhere (I won't say 'defined'), and 'Export' for those types specified in this file that may be used elsewhere." If "ontology" means theory, then I agree that it is not very useful to import and export theories, and that import and export statements probably don't make sense as part of theories. That does not mean that these constructs are not valuable constructs in ONT languages, with or without the Web. Without them, the languages just won't scale.Also, one of the most central and salient aspects of an ONT language is how it handles quantifiers, and what it can quantify over. You don't mention this anywhere, which I also find odd. Does Larch have quantifiers? (It is possible to treat quantification in terms of implicit universal quantification of variables and handling existentials by the deft use of functions, avoiding any need for an explicit quantifier scoping mechanism in the syntax. I'll make a guess that this is how Larch does it also.)Absolutely correct. This caused relatively few problems in our domains. How bad does it make things for ontologies?- *types* [classes/kinds/classes].Be careful of terminology. "types" often is understood to imply that type membership is syntactically checkable or used to determine wellformedness. This is quite unusual in ontology languages. If you really do just mean classes, then yes, almost all ontology languages have this.I was trying to indicate that I realized that there were various notions of type and class and that each ONT language probably picked just one of them. ...Actually isA is usually understood as the relationship between an individual and its type; the relation between types is often called subClass. Yes, it may be entailed by other axioms. (Actually to be honest this varies between languages, and is a good hallmark of computational/deductive complexity.)OK, I screwed up my terminology. My first instinct had been to use "subclass." I should have stuck with it. ... _________________________________________________________________ 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
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