RE: Sets and bags / Identity of a link



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Daniel Jackson (dnj@lcs.mit.edu)
Tue, 23 Jan 2001 15:15:57 -0500


joaquin, what are your criteria for what's basic and what isn't? here are two criteria: 1. mathematical: a notion is more basic if it's mathematically simpler, and if defining the other notion in terms of it is simpler than vice versa. in this respect, relations are the basic notion. to define a relation in terms of links, you need existential quantification. 2. phenomenological: a notion is more basic if it models reality more directly. in this respect, relations are also more basic, since if all you have is links, it's not clear how to model simple binary predicates. for example, how do i express an ordering on security levels (eg, top secret more than classified) with links? by the way, what are the East and West Coast schools? /daniel -----Original Message----- From: Joaquin Miller [mailto:miller@joaquin.net] Sent: Tuesday, January 23, 2001 2:50 PM To: puml-list@cs.york.ac.uk Cc: Trygve Reenskaug Subject: RE: Sets and bags / Identity of a link This message does not address the question about the possibility of two links of the same type between the same objects. The message simply points out something about this remark: Relations are a more basic notion, and therefore deserve to be built-in. You can always create a set of links. That is according to the East Coast school. The West Coast school would say something more like: Links are a more basic notion, and therefore deserve to be built-in. You can always define a relationship. Cordially, Joaquin ................................................ Joaquin Miller Chief Architect Financial Systems Architects mailto:joaquin@acm.org <mailto:joaquin@acm.org> San Francisco phone: +1 (510) 336-2545 fax: +1 (510) 336-2546 PGP Fingerprint: CA23 6BCA ACAB 6006 E3C3 0E79 2122 94B4 E5FD 42C3


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