- From: Danny Ayers <danny@panlanka.net>
- Date: Sun, 20 May 2001 22:35:44 +0600
- To: <www-rdf-logic@w3.org>
- Message-ID: <EBEPLGMHCDOJJJPCFHEFCEKJDHAA.danny@panlanka.net>
RE: Desirata for Symbols (was Re: What do the ontologists want)us:elvis job(rock'n'roll) wales:elvis job(saint) Though some might same these are equivalent. --- Danny Ayers http://www.isacat.net -----Original Message----- From: www-rdf-logic-request@w3.org [mailto:www-rdf-logic-request@w3.org]On Behalf Of Ziv Hellman Sent: 20 May 2001 20:33 To: Sandro Hawke; pat hayes Cc: www-rdf-logic@w3.org Subject: RE: Desirata for Symbols (was Re: What do the ontologists want) > > pat: > > sandro: > > >What possible advantage does "urn:elvis" (or any other > URI-like thing) > > >have over "elvis" as a logic symbol? > > > > > >1. We can prevent unintentional re-use. This is like > > > com.sun.SomeJavaClass or w3c_some_C_library_function. > Doing this > > > allows us to skip a symbol translation stage in reasoning about > > > two different expressions. > > > > Several problems with this include the fact that often, with names, > > one NEEDS to have 're-use' in order to refer to something. That is > > largely what names are for in social use of language, if you think > > about it. But I have argued this to death in earlier threads. > > Er yes -- that's why I said "prevent UNINTENTIONAL re-use." > > In logic terms, I believe this feature lets you make skolum > functions/constants. > Skolem functions are simply tools for eliminating existential quantifiers. For example, if one states that in a given population every person has a brother (ForAll x) (ThereExists y) Brother(x, y) then defining a Skolem function f provides a way of expressing a particular brother in each case -- given x, since you known that x has a brother, you can use f(x) to refer to "x's brother" (ForAll x) [ (ThereExists y) Brother(x, y) --> Brother( x, f(x) ] Which is all well and good ... but still has no bearing for the question of 'what possible advantage does "urn:elvis" (or any other URI-like thing) have over "elvis" as a logic symbol?' Cheers, Ziv
Received on Sunday, 20 May 2001 12:40:22 UTC