- From: Michael Kifer <kifer@cs.sunysb.edu>
- Date: Mon, 15 Oct 2007 20:05:48 -0400
- To: Jos de Bruijn <debruijn@inf.unibz.it>
- Cc: public-rif-wg@w3.org
Just wanted to infuse a healthy doze of a reality check regarding the following: Jos wrote: > > >> g- the value space is required to be a subset of the domain. This > >> means that every interpretation includes all value spaces of all data > >> types. This is unnecessary. > > > > So what? It makes the definition simple and uniform. > > It makes every domain infinite. For most kinds of rules (especially > those without equality in the head) this is not really a problem. > However, as soon as we have full use of equality, or deal with > extensions in the direction of FOL, then one often wants to talk about > finite models. > > > It also makes rule sets which only contain rules such as Forall ?x,?y > (?x=?y) inconsistent. I claim that this is undesirable. Apart from everything that was said about it, you should remember that we have function symbols. So, the domain is infinite whether you have data types or not. --michael
Received on Tuesday, 16 October 2007 00:06:16 UTC