- From: Richard Fikes <fikes@KSL.Stanford.EDU>
- Date: Mon, 02 Apr 2001 16:39:59 -0700
- To: pat hayes <phayes@ai.uwf.edu>
- CC: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>, kenb@ccs.neu.edu, www-rdf-logic@w3.org
> If KIF is taken to be a strict first-order language then there > is no way to guarantee, on semantic grounds, that all lists are > finite. The 'definition' of lists (also called 'sequences) in the > extant KIF literature is a little vague on just this issue. Chapter 8 of the "draft proposed American National Standard (dpANS)" of KIF (at http://logic.stanford.edu/kif/dpans.html) says that a list is a finite sequence of objects. The formal definition of a list (attached below) given in that chapter uses a sequence variable, as you say. The model theoretics document for KIF (at http://logic.stanford.edu/kif/semantics.tex) says that a variable assignment maps a sequence variable into a finite sequence of objects. So, the prose in chapter 8 and the prose in the semantics document are consistent in saying that lists are finite. > A working group is currently revising the KIF standard; the new > version (a draft of which in the form of a working paper will be > available soon) addresses this issue and provides a clear and > unambiguous semantics for sequence quantifiers. I expect the new standard document will indeed clarify many such issues. Richard ---------------------------------------------- > (defrelation list (?x) := > (exists (@l) (= ?x (listof @l))))
Received on Monday, 2 April 2001 19:40:45 UTC