Re: Sets and bags / Identity of a link



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Perdita Stevens (Perdita.Stevens@dcs.ed.ac.uk)
Wed, 24 Jan 2001 19:06:06 +0000 (GMT)


Yes -- and whatever we do it has to be consistently done! Briefly: The semantics says that every link has a unique association which is its declaration. (2-108. etc.) The notation guide talks about the existence of links *other than* instances of associations, such as those arising from global variables. Either is fine -- but not having attained the state of grace that would allow me to believe both of these simultaneously :-) I opted to believe the former. Then, since every link is an instance of an association, if there isn't an association between two classifiers there aren't any links. *Then* if you take what I called the static view of association (not actually identical to Joaquin's rephrasing), some messages may pass when there is no association -- e.g., because of global variables. Of course, if we define association differently, this problem will go away. But we have to decide which it is! Perdita -- Dr. Perdita Stevens Division of Informatics, University of Edinburgh www.dcs.ed.ac.uk/home/pxs Fax: +44 131 667 7209


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