- From: zhang lei <zhanglei@cs.sjtu.edu.cn>
- Date: Sat, 13 Nov 2004 19:32:55 +0800
- To: 梅婧 <mayyam@is.pku.edu.cn>
- Cc: www-rdf-interest@w3.org

Mayyam@is.pku.edu.cn wrote: > for example, it was said that > "if c \in CEXT(S(owl:SymmetricProperty)) iff <x,y> \in EXT(c) implies > <y,x> \in EXT(c)" > in short, c is a SymmetricProperty iff c(x,y)->c(y,x). Please note that the iff condition is actually: FOR ALL x, y: <x,y> \in EXT(c) implies <y,x> \in EXT(c). > > ok, now we turn to the RDF graph. > firstly, we only have two facts "c(x,y), c(y,x)" to be the set > S={c(x,y), c(y,x)}. then, S entail E={c is a SymmetricProperty} (what > is "if" tells us) > secondly, we add a new fact "c(x,z)" to have the set S'={c(x,y), > c(y,x), c(x,z)}. of course, c is not a SymmetricProperty any more, at > least it is unknown now! i.e., S' cannot entail E! S' does not satisfy the iff condition. -- Lei Zhang Everything starts from a dream. http://apex.sjtu.edu.cn/people/zhanglei

Received on Saturday, 13 November 2004 11:33:09 UTC